SURGERY

1. Anaphylaxis Anaphylaxis is a clinical diagnosis that can be difficult to recognize in surgical patients. Early
recognition is dependent on thorough physical examination (e.g. inspecting skin under the surgical drapes).

2. Power And Samply Size Type II error describes a study’s failure to detect an effect (e.g. difference between
groups) when one truly exists. The probability of a type II error is affected by sample size, outcome variability, effect size,
and significance level.

3. Pericardial Effusion Malignant pericardial effusions are often large and prone to recurrence. In addition to
acute management with pericardiocentesis, they often require prevention of reaccumulation, either via a pericardial
window or prolonged catheter drainage.

4. Cardiac Tamponade Cardiac tamponade may be recognized by Beck triad (hypotension, jugular venous
distension, distant heart sounds). Increasing pericardial pressure restricts diastolic filling of the right-sided heart
chambers, leading to decreased cardiac output and obstructive shock. Right atrial pressure and pulmonary capillary
wedge pressure (a reflection of left atrial pressure) are increased due to compression.

5. Pericardial Effusion Purulent pericarditis is an acute, rapidly fatal infection most commonly caused by
hematogenous spread of Staphylococcus aureus. Urgent echocardiography-guided pericardiocentesis is essential for
confirmation of the diagnosis and treatment.

6. Pericardial Effusion Malignancy (e.g. lung cancer) is a common cause of pericardial effusion, which may
appear on chest x-ray as an enlarged cardiac silhouette with clear lungs. Echocardiography is used to confirm the
diagnosis, evaluate for signs of subacute tamponade, and guide pericardiocentesis.

7. Blunt Thoracic Trauma Patients with blunt chest trauma may be at risk for serious intrathoracic injury.
Evaluation includes chest x-ray and ECG. Additional tests/interventions are based on the patient's hemodynamic stability,
mechanism of injury, and initial test findings.

8. Informed Consent Essential elements discussed during the informed consent process include the patient's
diagnosis, the risks and benefits of both the proposed treatment and treatment alternatives, and the risks of refusing
treatment.
9. Venous Thromboembolism Post-thrombotic syndrome occurs in > 50% of patients with a history of acute
deep venous thrombosis and is marked by the development of chronic venous insufficiency distal to the site of
thrombus. It usually presents with leg pain, edema, fatigue, superficial venous dilation, and/or ulcer. Treatment includes
exercise and compression.

10. Mitral Stenosis The expected hemodynamic alterations of mitral stenosis are elevated pulmonary artery
pressures with normal left ventricular pressures. The pulmonary hypertension is primarily passive, resulting from
transmission of elevated left atrial pressure backward to the pulmonary circulation. There may also be a reactive
component involving endothelin-mediated pulmonary arteriolar vasoconstriction and remodeling.

11. Mitral Stenosis The increase in blood volume and cardiac output associated with pregnancy can be poorly
tolerated in the setting of valvular disease. Symptomatic mitral stenosis is among the highest-risk conditions during
pregnancy; therefore, surgical repair, preferably with percutaneous intervention, should be performed prior to
pregnancy.
12. Acute Pericarditis Post-cardiac injury (Dressler) syndrome is a form of acute pericarditis that results from
immune-complex deposition in the pericardium. It can occur following any event or intervention (e.g. myocardial
infarction, coronary artery bypass graft surgery, percutaneous coronary intervention) that exposes the immune system
to cardiac antigens and typically has a latency period of several weeks to months.
13. Adrenal Insufficiency In patients with underlying chronic adrenal insufficiency, acute stressors (e.g. procedure,
illness, trauma) can trigger adrenal crisis, which presents with hypoglycemia and severe hypotension often refractory to
initial volume resuscitation. Treatment requires rapid volume repletion and administration of hydrocortisone or
dexamethasone.

14. Atrial Flutter Atrial flutter is recognized by saw-toothed flutter waves on ECG; the rhythm can be regular or
irregular depending on the variability of the ventricular response rate. Atrial flutter carries a similar risk of arterial
thromboembolization to atrial fibrillation and should be similarly managed with chronic anticoagulation.

15. Chronic Kidney Disease An arteriovenous fistula allows blood to bypass the high-resistance systemic capillaries,
resulting in decreased systemic vascular resistance (afterload), increased venous return (preload), and increased cardiac
output. A large arteriovenous fistula can lead to high-output heart failure.

16. Anesthesia Laparoscopic intra-abdominal surgery (e.g. cholecystectomy) requires insufflation of CO2 into
the abdomen to create space for surgical maneuvering and visibility. The increased intra-abdominal pressure stimulates
stretch receptors on the peritoneum that respond by triggering an increase in vagal tone. Consequently, patients can
develop severe bradycardia, atrioventricular block, and sometimes asystole.

17. Blunt Thoracic Trauma Persistent tachycardia and new arrhythmia (e.g. premature ventricular contractions)
after blunt chest trauma are concerning for blunt cardiac injury. Patients with these findings are admitted for continuous
cardiac monitoring and echocardiography.

18. CABG Pleural effusions occur in almost half of patients who undergo coronary artery bypass graft surgery. The
majority of these effusions are small, asymptomatic, and benign. When the effusion is small to moderate in size, begins
within 1 or 2 days of surgery, and does not cause respiratory symptoms, it can be managed conservatively with
observation.
19. CABG Mediastinitis is a complication of cardiovascular surgery characterized by infection of the deep tissues; it
classically presents with systemic symptoms (e.g. fever, tachycardia), chest pain, chest wall edema/crepitus, and
purulent discharge; but it can also present atypically. Therefore, any patient with copious drainage from the sternal
wound should undergo chest imaging. Radiographic findings include fluid collections or pneumomediastinum.

20. CABG Sternal dehiscence is a complication of cardiac surgery characterized by separation of the bony edges of
the sternum. Patients may report mild pain or sensation of chest wall instability and 'clicking' with chest movement. The
diagnosis can be made radiographically (e.g. displaced sternal wire) or clinically; palpable rocking or clicking of the
sternum confirms the diagnosis. Management involves urgent surgical exploration and repair.

21. Acute Limb Ischemia Indications for lower extremity amputation include nonrevascularizable limb ischemia,
unsalvageable soft-tissue damage, and life-threatening infection (e.g. infected gangrene).

22. Acute Limb Ischemia Due to pre-existing collateral circulation, acute limb ischemia in the setting of chronic
peripheral artery disease (PAD) often presents less dramatically than in patients without PAD. Emergency intervention is
still necessary.
23. Aortic Dissection Turner syndrome is due to partial or complete loss of an X chromosome. Common
manifestations include musculoskeletal (e.g. short stature, webbed neck), cardiovascular, renal, and ovarian (e.g.
infertility) disorders. Cardiovascular disease, including bicuspid aortic valve and aortic root dilation, places patients at an
increased risk for aortic dissection; this risk is further increased during pregnancy.

24. Aortic Dissection Type A dissections involve the ascending aorta and present with sudden-onset chest or
back pain that is severe and described as sharp or tearing. They may be complicated by syncope, stroke, myocardial
infarction, or heart failure and require immediate surgical intervention.

25. Aortic Dissection Cocaine can cause rapid and transient hypertension and is associated with aortic
dissection in young patients. There is typically sudden-onset, severe chest or back pain that is sharp or tearing, and
 pleural effusion may occur due to hemothorax.

26. Ehlers-Danlos Syndrome Ehlers-Danlos syndrome is a collection of genetic connective tissue disorders. It
is usually characterized by joint hypermobility/laxity, multiple joint dislocations, tissue fragility, poor wound healing, and
cigarette, paper-like scarring.

27. Aortic Aneurysm Pain is the most common manifestation of abdominal aortic aneurysm (AAA), and it can
vary according to aneurysm location. Proximal AAA tends to cause upper abdominal, flank, or back pain. In symptomatic,
hemodynamically stable patients, the diagnosis is best made by abdominal CT.

28. Tricuspid Regurgitation Tricuspid regurgitation is usually secondary (functional), resulting from right ventricular
cavity enlargement in the setting of chronic right-sided volume or pressure overload. A prominent V wave in jugular
venous pulsation is highly specific for tricuspid regurgitation.

29. Mechanical Valve A regurgitant murmur over a prosthetic valve suggests prosthetic valve dysfunction
(PVD) in the form of a paravalvular leak or transvalvular regurgitation. PVD can lead to serious complications (e.g. heart
failure) and should be promptly evaluated with echocardiography.

30. Mitral Regurgitation Acute mitral regurgitation results in sudden-onset large-volume backflow of blood from
the left ventricle to the left atrium. Neither chamber has time for compensatory dilation, leading to a rapid increase in
left ventricular end-diastolic pressure and left atrial pressure, resulting in pulmonary edema. Although forward blood
flow is reduced, left ventricular ejection fraction is normal or hyperdynamic due to a large amount of stroke volume
flowing backward into the left atrium through the low-resistance regurgitant pathway.

31. Mitral Regurgitation Timely surgical repair is the best treatment for chronic severe mitral regurgitation (MR)
of primary etiology. The measured left ventricular ejection fraction (LVEF) significantly overestimates the effective LVEF
in patients with severe MR; therefore, surgery is indicated for both symptomatic and asymptomatic patients with LVEF <
60%.
32. Aortic Stenosis In patients with severe aortic stenosis, surgical aortic valve replacement is indicated in all
symptomatic patients. It is also indicated in asymptomatic patients with left ventricular ejection fraction < 50% and those
undergoing other cardiac surgery.

33. Cardiac Tamponade Cardiac catheterization in patients with cardiac tamponade typically reveals elevated
and equilibrated intracardiac diastolic pressures. Urgent echocardiography should be performed in patients with
suspected cardiac tamponade for definitive diagnosis and management.

34. Pulmonary Stenosis Pulmonic valve stenosis usually occurs as a congenital defect and can often remain
asymptomatic until adulthood. Cardiac auscultation reveals an ejection click, followed by a crescendo-decrescendo
systolic murmur over the left second intercostal space and widened splitting of S2.

35. Tricuspid Regurgitation Transvenous lead placement through the tricuspid valve can cause severe tricuspid
regurgitation due to direct valve leaflet damage or inadequate leaflet coaptation. This complication should be suspected
in patients presenting with right-sided heart failure following implantable pacemaker or cardioverter-defibrillator
placement.
36. Myocardial Infarction Ventricular aneurysm occurs as a late complication (e.g. several months) following
transmural myocardial infarction, and is suggested by ECG demonstrating persistent ST-segment elevation with deep Q
waves. Patients most commonly have progressive left ventricular enlargement and dyskinetic wall motion leading to
heart failure.
37. Cardiogenic Shock Patients with perioperative myocardial infarction may lack chest pain and can develop
cardiogenic shock due to left ventricular systolic dysfunction. Pulmonary artery catheterization reveals a low cardiac
index and elevated pulmonary capillary wedge pressure.
38. AV Fistula An arteriovenous fistula can develop as a complication of vascular access during cardiac
catheterization. Patients typically have mild localized pain and swelling and a continuous bruit accompanied by a
palpable thrill over the fistula site.

39. Aortic Dissection Acute type A aortic dissection can extend into the pericardial space, causing
hemopericardium and rapidly progressing to cardiac tamponade and cardiogenic shock. CT angiography is the initial
diagnostic study of choice in hemodynamically stable patients and reveals an intimal flap separating the true and false
lumens in the ascending or descending aorta.

40. Aortic Aneurysm The management of small to moderately sized (i.e. 3 cm to 5.5 cm) abdominal aortic
aneurysms (AAAs) involves lifestyle modification, with smoking cessation as the best intervention to minimize AAA
progression.
41. Blunt Thoracic Trauma Patients with trauma from rapid deceleration are at risk for blunt thoracic aortic injury
(BTAI). All patients with blunt chest trauma require a chest x-ray after initial trauma survey. Chest x-ray findings
concerning for BTAI include widened mediastinum, abnormal aortic contour, and/or left-sided effusion (hemothorax).

42. Compartment Syndrome Ischemia-reperfusion syndrome is a form of compartment syndrome that occurs
following reperfusion of an acutely ischemic limb. Symptoms include severe pain that is worsened on passive range of
motion, paresthesias, and sensory and motor deficits. The diagnosis is confirmed by measuring compartment pressures.
Definitive management includes urgent fasciotomy.

43. Cardiac Tamponade Acute cardiac tamponade is due to rapid accumulation of a small amount of fluid within
a stiff pericardium, causing a sudden rise in intrapericardial pressure. Unlike subacute tamponade, the cardiac silhouette
can be normal on chest x-ray.

44. Blunt Thoracic Trauma Patients with trauma following rapid deceleration are at risk for blunt thoracic aortic
injury. Signs may include upper extremity hypertension with lower extremity hypotension (pseudocoarctation) and/or a
hoarse voice (left recurrent laryngeal nerve stretching).

45. Blunt Thoracic Trauma Although shock in the trauma setting is initially assumed to be hypovolemic shock (from
hemorrhage), elevated central venous pressure (CVP) is more consistent with obstructive or cardiogenic shock. Blunt
cardiac injury with myocardial dysfunction can cause cardiogenic shock with elevated CVP and refractory hypotension.

46. Peripheral Vascular Disease Aortoiliac occlusion (Leriche syndrome) is characterized by the triad of bilateral
hip, thigh, and buttock claudication; impotence; and absent or diminished femoral pulses (often with symmetric atrophy
of the bilateral lower extremities due to chronic ischemia).

47. Acute Limb Ischemia Sudden development of limb ischemia in a previously asymptomatic patient is most
consistent with embolic arterial occlusion. Most arterial emboli are cardiac in origin.

48. Retroperitoneal Hematoma Retroperitoneal hematoma can occur as a local vascular complication of cardiac
catheterization, and often presents with sudden hemodynamic instability and ipsilateral flank or back pain. Diagnosis is
confirmed with noncontrast CT scan of abdomen and pelvis or abdominal ultrasonography. Treatment is usually
supportive with bed rest, intensive monitoring, and intravenous fluids and/or blood transfusion.

49. Peripheral Vascular Disease Ankle-brachial index is a noninvasive test that is highly sensitive and specific for
peripheral arterial disease in symptomatic patients. It is the preferred first step to confirm the diagnosis in most cases.

50. Cardiac Tamponade A pericardial effusion appears as an enlarged, 'water bottle'-shaped cardiac silhouette on
chest x-ray. Physical examination findings of effusion without cardiac tamponade include diminished heart sounds on
auscultation and a maximal apical impulse that is difficult to palpate.
51. Cardiac Tamponade Cardiac tamponade can occur as a catastrophic complication of acute aortic dissection. It
should be suspected in patients with hypotension, tachycardia, distended neck veins, and pulsus paradoxus who have
sudden onset of severe tearing chest pain radiating to the back.

52. Peripheral Artery Aneurysms Peripheral artery aneurysm manifests as a pulsatile mass that can compress
adjacent structures (nerves, veins), and can result in thrombosis and ischemia. Popliteal and femoral artery aneurysms
are the most common peripheral artery aneurysms. They are frequently associated with abdominal aortic aneurysms.

53. Aortic Aneurysm In patients with hemodynamic instability and signs and symptoms consistent with an
abdominal aortic aneurysm (AAA) but without a known history, a focused bedside ultrasound should be performed. A CT
scan is helpful in symptomatic patients who are stable, while those who are unstable with a known history of AAA should
undergo emergent repair.

54. Chronic Venous Insufficiency Venous insufficiency (valvular incompetence) is the most common cause of
lower extremity edema. It classically worsens throughout the day and resolves overnight when the patient is recumbent.

55. Aortic Aneurysm Ruptured abdominal aortic aneurysm presents with the acute onset of severe abdominal
or flank pain, sometimes accompanied by syncope, a pulsatile abdominal mass, and/or flank or umbilical hematomas.
The onset of hemodynamic instability can be abrupt or delayed.

56. Central Venous Catheter Complications due to inappropriate central venous catheter placement are
common. With the exception of select cases, appropriate catheter tip placement should be confirmed by chest x-ray
prior to catheter use.

57. Gunshot Injury Hard signs of vascular injury include pulsatile bleeding, bruits or thrills over the injury, an
expanding hematoma, and signs of distal ischemia (e.g. absent pulses, cool extremities). In the presence of a penetrating
injury, such signs are almost universally predictive of the need for urgent surgical repair.

58. Atrial Myxoma Myxomas are the most common primary cardiac neoplasm and usually arise in the left atrium.
Fragments of the tumor can dislodge and lead to systemic embolization (e.g. stroke, acute limb ischemia). The tumors
may also cause position-dependent obstruction of the mitral valve, leading to a mid-diastolic murmur and symptoms of
decreased cardiac output (e.g. dyspnea, syncope). Constitutional symptoms (e.g. fever, weight loss) may also be present.

59. Acute Limb Ischemia As soon as acute limb ischemia is clinically diagnosed (e.g. pallor, pulselessness),
anticoagulation (e.g. intravenous heparin infusion) should be initiated. This prevents thrombus propagation and distal
thrombosis while the patient undergoes further diagnostic procedures or awaits surgical intervention.

60. Aortic Aneurysm Bowel ischemia and infarction are possible early complications of operation on the
abdominal aorta, such as AAA repair.

61. Mediastinitis Acute mediastinitis can occur following cardiac surgery and present with fever, chest pain,
leukocytosis, and mediastinal widening on chest x-ray. It is a serious condition that requires drainage, surgical
debridement, and prolonged antibiotic therapy.

62. Myocardial Infarction Papillary muscle rupture leading to acute mitral regurgitation and cardiogenic shock is a
mechanical complication of acute myocardial infarction and usually occurs 3-5 days after the infarct.

63. Thermal Burn Superficial burns involve only the epidermis and are characterized by erythema, pain, intact
capillary refill, and lack of blistering or weeping. They do not require debridement and can be managed with simple
wound care (e.g. cleansing, moisturization).

64. Melanoma The ABCDE criteria can assist in evaluation of superficial spreading melanoma but are less
sensitive for other types of melanoma (e.g. nodular, atypical). Nodular melanomas, the second most common type of
 melanoma, usually grow vertically and have symmetric borders and a uniform, dark color. Suspicion should be raised
when the lesion appears different from other lesions on the patient ('ugly duckling sign') or the lesion grows
continuously, is elevated, or is firm.

65. Melanoma The assessment of pigmented skin lesions should include a predictive rule to estimate the risk of
melanoma, such as the ABCDE (Asymmetry, Border irregularities, Color variation, Diameter, Evolving) rule; lesions with >
1-2 of the ABCDE criteria warrant excisional biopsy. Biopsy is also recommended for lesions with inflammation; itching,
crusting, or bleeding; or sensory changes and for lesions that are significantly different in appearance from other
pigmented spots on the same patient (ugly duckling sign).

66. Diabetic Foot A diabetic foot ulcer is a common complication of long-standing diabetes mellitus and is
particularly common in patients with neuropathy and peripheral vascular disease. Deep, long-standing, or large ulcers
require foot imaging (e.g. x-ray, MRI) to assess for underlying osteomyelitis, even when no signs or symptoms of soft
tissue infection are present. Ulcers associated with elevated erythrocyte sedimentation rate or C-reactive protein also
require imaging.

67. Pyoderma Gangrenosum Pyoderma gangrenosum is characterized by rapidly progressive, painful ulcers
with a purulent base and violaceous border, often following local trauma (pathergy). Many patients have underlying
systemic inflammatory disorders (e.g. rheumatoid arthritis, inflammatory bowel disease). The diagnosis is made clinically
after excluding other etiologies, usually with skin biopsy. Treatment is with corticosteroids.

68. Keratoacanthoma A keratoacanthoma presents as a rapidly growing nodule with ulceration and a central
keratin plug. It frequently regresses and may resolve spontaneously over several months. Although keratoacanthomas
often have a benign course, some lesions may progress to invasive squamous cell carcinoma.

69. Nonmelanoma Skin Cancer Basal cell carcinoma (BCC) rarely metastasizes but can be locally invasive.
Nodular BCC on the trunk or extremities is typically managed with surgical excisional biopsy with narrow (3-5 mm)
margins. For the face and other delicate or cosmetically sensitive areas, Mohs micrographic surgery (sequential removal
of thin skin layers with microscopic inspection) is more often performed.

70. Hidradenitis Suppurativa Management of hidradenitis suppurativa initially involves topical or oral
antibiotics, depending on the severity. For severe or refractory disease, tumor necrosis factor-α inhibitors, oral retinoids,
and surgical excision may be warranted.

71. Nonmelanoma Skin Cancer Angiosarcoma is a malignant tumor derived from the lining of blood vessels and
lymphatics. Patients who have received localized radiation therapy for cancer treatment (e.g. breast cancer) are at risk of
developing secondary angiosarcoma of the skin. Breast cancer survivors with chronic lymphedema are also at risk.

72. Epidermoid Cyst Epidermal inclusion cyst is a benign nodule containing squamous epithelium that
produces keratin. It presents as a dome-shaped, firm, freely movable cyst or nodule with a small central punctum. The
lesion can remain stable or gradually increase in size but may produce a cheesy white discharge; it usually resolves
spontaneously.
73. Pyoderma Gangrenosum Pyoderma gangrenosum causes a rapidly progressive and painful ulcer with a
purulent base and violaceous border. Most patients have associated systemic disease (e.g. inflammatory bowel disease).
Diagnosis is made clinically after excluding other etiologies, usually with skin biopsy.

74. Hidradenitis Suppurativa Hidradenitis suppurativa is a chronic, relapsing condition characterized by

inflammatory occlusion of folliculopilosebaceous units. It most commonly occurs in intertriginous skin areas and presents
as painful nodules that can progress to abscesses that open to the skin surface. Complications include sinus tracts,
comedones, and scarring.

75. Pressure Induced Injury Prolonged pressure over a bony prominence can cause ischemic necrosis of overlying
tissues, leading to a pressure (decubitus) ulcer. Risk factors include impaired mobility, malnutrition, abnormal mental
 status, decreased skin perfusion, and reduced sensation.

76. Thermal Burn Severe burns are often complicated by wound infections and sepsis. Risk is increased with large
burns (> 20% body surface area). Gram-positive organisms are common soon after injury; gram-negative organisms and
fungi are more common after 5 days. A change in burn wound appearance or the loss of skin graft is often the first sign of
a burn wound infection.

77. Nonmelanoma Skin Cancer Squamous cell carcinoma is the most common malignancy of the lower lip. Risk
factors include sun exposure, fair skin, tobacco use, immunosuppression, and chronic inflammation. Biopsy is
characterized by invasive cords of squamous cells with keratin pearls.

78. Melanoma On clinical examination, features of a lesion that suggest melanoma include Asymmetry, Border
irregularities, Color variation, Diameter > 6 mm, and Evolution in color, size, or shape.

79. Nonmelanoma Skin Cancer Squamous cell carcinoma (SCC) is the most common skin malignancy in patients
on chronic immunosuppressive therapy for a history of organ transplant. SCC in immunosuppressed patients is more
aggressive, with an increased risk of local recurrence and regional metastasis.

80. Pressure Induced Injury Risk factors for pressure ulcers include decreased mobility, malnutrition, abnormal
mental status, decreased skin perfusion, and reduced sensation. Interventions that can prevent pressure ulcers include
proper positioning for pressure redistribution, mobilization, careful skin care, moisture control, and maintenance of
nutrition.
81. Nonmelanoma Skin Cancer Squamous cell carcinoma (SCC) is most often associated with ultraviolet (sun)
exposure but may also arise in chronically wounded, scarred, or inflamed skin. SCC arising in chronic wounds tends to be
more aggressive.

82. Melanoma A mole may represent melanoma if it appears substantially different from others ('ugly duckling
sign'), itches or bleeds, or develops nodularity. If melanoma is suspected, an excisional biopsy should be obtained.

83. Nonmelanoma Skin Cancer A nonhealing, painless, bleeding skin ulcer associated with a chronic scar
suggests squamous cell carcinoma (SCC). SCC arising within a scar or chronic wound carries an increased risk of
metastasis. The diagnosis should be confirmed with biopsy.

84. Nonmelanoma Skin Cancer Nodular basal cell carcinoma has low metastatic potential but should be
removed with either electrodessication and curettage or surgical excision. Mohs micrographic surgery, in which thin
layers are removed and inspected microscopically to ensure clear margins, is used for high-risk lesions in delicate or
cosmetically sensitive areas.

85. Dental Injury An avulsed permanent tooth should be reimplanted as soon as possible. The tooth can be briefly
stored in cold milk or saliva and manually reimplanted after gentle rinsing of the tooth and socket with normal saline.

86. Ear Trauma Blunt trauma to the ear can cause an auricular hematoma, which is a collection of blood
between the perichondrium and cartilage of the outer ear. Prompt evacuation of the hematoma is required to avoid
complications of infection, avascular necrosis, and permanent cauliflower ear deformity.

87. Osteonecrosis Bisphosphonate-related osteonecrosis of the jaw is characterized by chronic swelling, mild pain,
and exposed, necrotic bone. It is often triggered by tooth extractions or other invasive dental procedures. The course can
be intractable, and treatment is largely supportive with careful oral hygiene and antibacterial rinses.

88. Ear Trauma Barotrauma to the ear occurs most commonly after flying and can result in injury (e.g. ear pain,
hearing loss) to the tympanic membrane (TM). Most barotraumatic TM injuries heal spontaneously within a few weeks.
89. Epistaxis A septal hematoma presents after nasal trauma as fluctuant swelling of the nasal septum. It
should be recognized and promptly drained to avoid complications of infection, septal perforation, and nasal
deformities.
90. Cerebrospinal Fluid Rhinorrhea Clear, unilateral rhinorrhea that increases at times of relatively increased
intracranial pressure (e.g. bending over, bowel movements) is suspicious for cerebrospinal fluid rhinorrhea, which is
most often caused by head trauma and can result in meningitis.

91. Otosclerosis A conductive hearing loss (CHL) may show improved speech understanding in background noise.
CHL in a young woman with a positive family history of hearing loss likely represents otosclerosis, which is characterized
by bony overgrowth of the stapes that causes stiffening of the ossicular chain.

92. Vertigo A perilymphatic fistula can occur after head trauma and result in episodic vertigo triggered by sudden
pressure changes (e.g. Valsalva maneuvers) or loud noises (Tullio phenomenon).

93. Recurrent Respiratory Papillomatosis Human papillomavirus can cause recurrent respiratory papillomatosis,
which results in hoarseness due to wartlike growths on the true vocal cords.

94. Thyroid Cancer Thyroglobulin is produced only by thyroid tissue (either normally functioning or malignant).
Serum thyroglobulin measurements are used as a tumor marker once the normally functioning thyroid tissue is removed.

95. Thyroid Cancer Thyroid nodules that have suspicious sonographic features should undergo fine-needle
aspiration biopsy, even if the patient is pregnant.

96. Thyroid Cancer Medullary thyroid cancer arises from the calcitonin-secreting parafollicular C cells. Serum
calcitonin levels correlate with the risk of metastasis and recurrence, and are measured serially following surgery.

97. Airway Emergency A postoperative neck hematoma should be recognized promptly and drained to avoid
potentially lethal upper airway obstruction.

98. Head And Neck Cancers A laryngeal ulcer in a smoker is likely squamous cell carcinoma. Persistent hoarseness
should always be evaluated by laryngoscopy to ensure no delay in diagnosis of possible cancer.

99. Head And Neck Cancers Evolving leukoplakia in the oral cavity requires biopsy (even if previously biopsied).
Tobacco use is the most important risk factor for oral cavity squamous cell carcinoma.

100. Head And Neck Cancers A tonsil ulcer in a smoker is likely due to squamous cell carcinoma.

101. Head And Neck Cancers An enlarged, ulcerated tonsil with ipsilateral cervical adenopathy is likely
oropharyngeal (head and neck) squamous cell carcinoma. Human papillomavirus is the likely etiology in the absence of
traditional risk factors (smoking, alcohol).

102. Head And Neck Cancers In a patient with risk factors for malignancy, ear pain with a normal ear
examination may be referred from the base of the tongue or hypopharynx/larynx. Associated cervical adenopathy makes
head and neck squamous cell carcinoma the most likely diagnosis.

103. Branchial Cleft Cysts A branchial cleft cyst is a congenital neck mass that often presents in later
childhood after an upper respiratory tract infection. It is typically located inferior to the mandible and anterior to the
sternocleidomastoid muscle.

104. Vestibular Schwannoma Unilateral sensorineural hearing loss with imbalance (CN VIII dysfunction) and
decreased facial sensation (CN V dysfunction) are concerning for a vestibular schwannoma, a benign tumor of CN VIII.
105. Epiglottitis Patients with epiglottitis who develop rapid-onset respiratory failure (e.g. tripod
position, hypoxia, drooling, tachypnea) require urgent airway management. This includes bag-valve-mask ventilation
with 100% oxygen followed by endotracheal intubation with advanced equipment (e.g. video laryngoscope). A single
failed attempt at video-assisted endotracheal intubation should prompt surgical cricothyrotomy, which bypasses the
epiglottal swelling and potential obstruction.

106. Epiglottitis Epiglottitis should be suspected in patients with sore throat, hoarseness, stridor, pooled
oral secretions, and drooling. Risk factors include diabetes mellitus, obesity, and preceding upper respiratory infection.
The diagnosis can be confirmed (in those with stable respiratory status) using lateral neck radiograph.

107. Nasopharyngeal Carcinoma Nasopharyngeal carcinoma is a tumor associated with Epstein-Barr virus
reactivation that most commonly affects individuals living in southern China. Manifestations are due to nasopharyngeal
obstruction or invasion of adjacent tissues and include nasal congestion with epistaxis, headache, diplopia, cranial nerve
deficits (e.g. facial numbness), and otitis media. Early metastasis to the cervical lymph nodes is common.

108. Salivary Gland Tumors Sialadenosis is a benign, noninflammatory enlargement of the salivary glands,
often caused by chronic alcohol use.

109. Otosclerosis Otosclerosis causes fixation of the stapes, which results in conductive hearing loss. It
often presents in young women and may progress during pregnancy.

110. Salivary Gland Tumors Parotid masses are typically benign. Cranial nerve dysfunction (facial droop,
facial numbness) increases concern for malignancy.

111. Acute Parotitis Suppurative parotitis presents with exquisitely painful swelling of the parotid gland. This
postoperative complication can be prevented with adequate fluid hydration and oral hygiene.

112. Nasopharyngeal Carcinoma Nasopharyngeal carcinoma is associated with the reactivation of

Epstein-Barr virus and occurs most commonly in those from Asia (particularly southern China) and parts of Africa and the
Middle East. Manifestations include nasal congestion with epistaxis, headaches, cranial nerve palsies, and otitis media.
Early spread to the cervical lymph nodes is common.

113. Deviated Nasal Septum If a patient develops a whistling noise during respiration following rhinoplasty,
one should suspect nasal septal perforation likely resulting from a septal hematoma.

114. Bone Tumor Torus palatinus (TP) is a benign bony growth (exostosis) located on the midline suture of
the hard palate. It can be congenital or develop later in life. TP is typically chronic and asymptomatic, and the diagnosis is
usually clinically evident. Surgery is indicated if the mass becomes symptomatic, interferes with speech or eating, or
causes problems with the fitting of dentures.

115. Retropharyngeal Abscess Retropharyngeal abscess presents with neck pain, odynophagia, and
fever following penetrating trauma to the posterior pharynx. Infection within the retropharyngeal space can drain into
the superior mediastinum. Extension through the alar fascia into the 'danger space' can transmit infection into the
posterior mediastinum and result in acute necrotizing mediastinitis.

116. Sialolithiasis Salivary stones occur most often in the submandibular glands and can present with
recurrent sialadenitis due to obstruction of the duct.

117. Peritonsillar Abscess A muffled voice should make one consider a diagnosis other than uncomplicated
pharyngitis or tonsillitis. A peritonsillar abscess is a potential complication of tonsillitis and requires both intravenous
antibiotic therapy and urgent drainage of the abscess. Deviation of the uvula and unilateral lymphadenopathy can be
helpful in distinguishing a peritonsillar abscess from epiglottitis.
118. Acromegaly Joint involvement in acromegaly is common and often involves both axial and
appendicular skeleton. Excessive growth hormone causes hyperplasia of articular chondrocytes and synovial
hypertrophy, which may be visible on x-ray as widening of the joint space. However, in later stages, degeneration of the
cartilage may lead to clinical and radiographic findings resembling osteoarthritis.

119. Diabetes Mellitus Stress hyperglycemia is a transient elevation in blood glucose that occurs as a
physiologic response to severe illness or injury. Mild elevations do not require treatment. Marked elevations (e.g. > 180-
200 mg/dL) are associated with increased mortality and should be corrected with short-acting insulin, with a target
glucose of 140-180 mg/dL.

120. Hyponatremia The administration of desmopressin, an analogue of antidiuretic hormone (ADH), can
induce the syndrome of inappropriate ADH secretion. Urinary water excretion is impaired, leading to hypotonic
hyponatremia. Laboratory studies, including serum electrolytes, urine osmolality, and urine sodium, are the first step in
establishing the diagnosis.

121. Thyroid Nodules The initial evaluation of thyroid nodules includes a serum TSH assay and thyroid
ultrasound. Patients with a suppressed TSH should undergo thyroid scintigraphy. Small, hyperfunctioning nodules are
rarely malignant and do not usually require fine-needle aspiration.

122. Hyperparathyroidism Patients with long-standing chronic kidney disease often have hypocalcemia and
hyperphosphatemia, which can lead to chronic parathyroid stimulation. Over time, this can cause parathyroid
hyperplasia and autonomous parathyroid hormone (PTH) secretion. The net effect, termed tertiary hyperparathyroidism,
is characterized by hypercalcemia, hyperphosphatemia, and extremely high serum PTH levels.

123. Pheochromocytoma Pheochromocytoma commonly presents with episodic headaches and

hypertension and can cause unexplained hyperglycemia. Measurement of urine or plasma metanephrines is the initial
step in diagnostic evaluation.

124. Pheochromocytoma Von Hippel-Lindau disease (VHL) is an inherited disorder caused by mutations in
the VHL gene. It is associated with retinal and CNS hemangioblastomas, which are heavily vascular tumors that can lead
to hemorrhage or mass effect symptoms in the brain and spinal cord. Other manifestations include clear cell renal cell
carcinoma, pancreatic neuroendocrine tumors, endolymphatic sac tumors of the middle ear, and pheochromocytomas.

125. Pheochromocytoma All pheochromocytomas should undergo surgical resection, which is a high-risk
procedure due to the potential for intraoperative catecholamine surges and related complications. To reduce this risk,
patients should initiate preoperative α-adrenergic blockade 7-14 days prior to surgery, followed by β-adrenergic
blockade 2-3 days prior to surgery. β-blocker therapy should never be given in the absence of α blockade due to the risk
of precipitating hypertensive crisis.

126. Hyperthyroidism Thyroid storm is a life-threatening thyrotoxicosis often triggered by thyroid or

non-thyroid surgery, trauma, infection, iodine contrast, or childbirth. It is characterized by tachycardia, hypertension,
cardiac arrhythmias, high fever, tremor, altered mentation, and lid lag.

127. Hypoparathyroidism Hypoparathyroidism (parathyroid hormone deficiency) is characterized by low

calcium and elevated phosphorus levels in the presence of normal renal function. Causes of hypoparathyroidism include
postsurgical, autoimmune parathyroid destruction, and defective calcium-sensing receptor. Hypocalcemia is the most
common complication seen post thyroidectomy.

128. Hypercalcemia Hypercalcemia can occur in prolonged immobilization due to increased osteoclastic
activity, especially in individuals with a high baseline rate of bone turnover. Bisphosphonates can reduce this
hypercalcemia and prevent bone loss.
129. Hypocalcemia High-volume blood transfusion can cause symptomatic hypocalcemia due to chelation of
ionized calcium by citrate in transfused blood. Patients with impaired hepatic function are at increased risk due to
decreased clearance of citrate by the liver.

130. Adrenal Insufficiency Patients on chronic glucocorticoid therapy often have secondary adrenal
insufficiency and can develop adrenal crisis when exposed to an acute stressor (e.g. surgery, illness, trauma). Adrenal
crisis primarily presents with hypotension and shock that is refractory to initial volume resuscitation. Treatment requires
intravenous hydrocortisone or dexamethasone in addition to aggressive volume repletion.

131. Pheochromocytoma Pheochromocytomas are catecholamine-producing tumors arising from

chromaffin cells of the adrenal medulla. Paroxysms of severe hypertension in patients with pheochromocytoma can be
precipitated by surgical procedures, induction of anesthesia, and a number of medications.

132. Thyroid Cancer Surgical resection is the primary treatment modality for papillary thyroid carcinoma.
Postoperative adjuvant therapies for patients at increased risk of recurrence include radioiodine ablation and
suppressive doses of thyroid hormone.

133. Euthyroid Sick Syndrome Thyroid function tests are often abnormal in patients with severe, acute
illness. The most common pattern is low T3 with normal T4 and TSH (i.e. euthyroid sick syndrome), which may represent
an adaptive response to severe illness. Thyroid hormone supplementation is not indicated for these patients, and follow-
up testing should be delayed until the patient has returned to baseline health.

134. Peripheral Neuropathy Neuropathic ulcers are caused by repeated pressure, friction, or trauma due to
lack of sensation in the local tissues. They typically occur at weight-bearing sites on the sole of the foot. Diabetes mellitus
is the most common cause of neuropathic ulcers.

135. Hyperparathyroidism The most common presentation of primary hyperparathyroidism is

asymptomatic hypercalcemia with an elevated parathyroid hormone level. Parathyroidectomy is recommended for
patients with symptomatic hypercalcemia and those with complications (e.g. nephrolithiasis) or at increased risk for
complications. Younger patients (age < 50) are likely to have complications during their lifetime and should be offered
surgery.
136. Breast Cancer Inflammatory breast carcinoma (IBC) is an aggressive breast cancer that can present with
unilateral breast rash, erythema, and edema. Metastatic disease (e.g. axillary lymphadenopathy) is common on initial
presentation. Patients require core needle breast biopsy and full-thickness skin punch biopsy for diagnosis.

137. Nipple Discharge Unilateral, spontaneous, bloody nipple discharge accompanied by a palpable
breast mass is concerning for malignancy.

138. Breast Cancer Lymphatic drainage from the breast passes primarily to the axillary lymph nodes, with
drainage traveling from lateral to medial, posterior to the pectoralis minor muscle. The pectoralis minor muscle is the
landmark for distinguishing the surgical levels of axillary lymph nodes during axillary lymph node dissection.

139. Breast Cancer Breast conserving therapy typically consists of partial mastectomy and axillary sentinel
lymph node biopsy, followed by whole breast radiation therapy. Adequate surgical excision of the cancer requires
negative margins.

140. Breast Mass Symptomatic simple breast cysts can be managed with fine-needle aspiration. Breast
cysts that contain bloody fluid or that do not resolve with aspiration require core needle biopsy to evaluate for breast
cancer.
141. Incisional Hernia Patients with a complete small bowel obstruction (e.g. obstipation, no air in the
rectum on abdominal x-ray) require nasogastric tube insertion for gastric decompression plus emergency laparotomy
due to the high risk of life-threatening complications (e.g. bowel ischemia, perforation).
142. Ovarian Cyst A ruptured ovarian cyst can cause hemoperitoneum, which presents with abdominal
rigidity, rebound, guarding, and referred shoulder pain. Hemodynamically unstable patients with peritoneal signs require
emergency surgery.

143. Breast Mass Palpable breast masses in women age < 30 are initially evaluated with breast ultrasound
due to increased density of breast tissue. Solid or complex-appearing masses on ultrasound may require additional
imaging (e.g. mammography) or biopsy to exclude malignancy.

144. Breast Mass An isolated, firm, well circumscribed, and mobile breast mass in women age < 30 is
commonly a benign fibroadenoma.

145. Breast Abscess Breast abscesses present with a unilateral fluctuant, tender, palpable breast mass with
fever, surrounding erythema/pain, and associated axillary lymphadenopathy. Management includes drainage (e.g.
needle aspiration) and empiric antibiotics (e.g. dicloxacillin, cephalexin).

146. Breast Mass Fat necrosis of the breast is a benign condition with clinical and radiographic findings
similar to breast cancer, including skin or nipple retraction and calcifications on mammography. Biopsy will reveal fat
globules and foamy histiocytes in fat necrosis. No further workup is indicated for excised lesions.

147. Breast Mass Mammography is the first-line imaging study for assessing a palpable breast mass in
women age > 30. Ultrasound may be added for better characterization of the mass. Tissue biopsy is required to confirm
the diagnosis.
148. Biliary Cyst The initial presentation of a biliary cyst may be acute cholangitis and should be
suspected in a patient with fever, right upper quadrant pain, and obstructive jaundice, as well as a cystic bile duct mass.
Initial management of acute cholangitis is urgent biliary drainage (i.e. endoscopic sphincterotomy); complete surgical
excision of the cyst should be performed later to reduce the risk of cholangiocarcinoma.

149. Colorectal Polyps And Cancer Adenocarcinoma in the left side of the colon may obstruct the flow of
stool, leading to altered bowel habits; visible hematochezia is common. In contrast, in the right side of the colon,
obstructive symptoms are uncommon, and any associated bleeding can be diluted by stool and is less likely to be visible;
therefore, right-sided colon cancer often presents with occult bleeding and iron deficiency anemia.

150. Colorectal Polyps And Cancer The liver is the most common organ affected by metastatic colon
adenocarcinoma. Surgical resection can be curative when metastatic colon cancer is confined to the liver. Regardless of
stage, resection of the primary tumor is recommended for patients with obstruction or threatened obstruction of the
colonic lumen.
151. Colorectal Cancer Screening Hyperplastic polyps are a non-neoplastic abnormality commonly found
on screening colonoscopy. Small hyperplastic polyps do not increase the risk for colon cancer, and patients may continue
colorectal screening at the usual intervals (e.g. repeat colonoscopy in 10 years for individuals at otherwise average risk).

152. Colorectal Cancer Screening Although most patients with localized (e.g. stage 1) colon
adenocarcinoma are cured after surgical resection, some develop recurrent neoplastic lesions of the colon. Therefore, a
colonoscopy should be performed 1 year after surgical resection and every 3-5 years thereafter.

153. Colorectal Polyps And Cancer Obesity and type 2 diabetes are associated with an increased risk of
colorectal adenocarcinoma, likely due to hyperinsulinemia. Hyperinsulinemia results in increased circulating levels of
insulin-like growth factor-1, which inhibits colorectal epithelial cell apoptosis and promotes neoplastic progression.

154. Compartment Syndrome The increased intra-abdominal and intrathoracic pressure seen in
abdominal compartment syndrome can cause significant cardiovascular consequences, including venous compression
with increased central venous pressure, decreased venous return to the heart (decreased cardiac preload), and
decreased cardiac output.
155. Acute Pancreatitis Severe acute pancreatitis (SAP) occurs in 15%-25% of patients with acute
pancreatitis and causes failure of > 1 organ systems lasting > 48 hours. Predictors of SAP include signs of the systemic
inflammatory response syndrome and evidence (e.g. elevated blood urea nitrogen or hematocrit) of intravascular
volume depletion. Patients with SAP have increased risk of morbidity and mortality and usually require intensive
monitoring.
156. Sepsis Infected pancreatic necrosis should be suspected in patients who develop worsening abdominal
pain, unstable vital signs, or signs (e.g. fever, leukocytosis) of infection 7-10 days after onset of acute necrotizing
pancreatitis. CT scan of the abdomen demonstrating gas within the pancreatic necrotic collection is diagnostic.

157. Chronic Diarrhea Bile acid diarrhea is a common complication of cholecystectomy and occurs due
to the overly rapid release of bile into the intestines, where it overwhelms the resorptive capacity of the terminal ileum
and spills into the colon, resulting in secretory (fasting) diarrhea. Bile-acid binding resins (e.g. cholestyramine, colestipol,
colesevelam) are first-line therapy.

158. Thermal Burn Enteral nutrition is the optimal form of nutrition for patients with moderate to severe
burn injuries. Early initiation helps offset the hypermetabolic response present after burn injury and has multiple clinical
benefits (e.g. maintenance of gut integrity, reduced rate of sepsis, decreased mortality).

159. Proctitis Radiation proctitis (RP) is caused by mucosal damage associated with pelvic radiation
therapy. Acute RP presents < 8 weeks postradiation with diarrhea, tenesmus, and mucus discharge, whereas chronic RP
occurs months to years after radiation, resulting in hematochezia, anemia, and possibly strictures. Colonoscopy
demonstrates mucosal pallor, friability, and telangiectasias confined to the rectum.

160. Hemorrhoids Thrombosed external hemorrhoids usually appear as purple or blue anal bulges below
the dentate line and may cause severe pain. Although conservative management (e.g. fiber, stool softeners, topical anti-
inflammatories and antispasmodics) is usually indicated, patients with severe pain should undergo hemorrhoidectomy
under local anesthesia.

161. Fecal Incontinence Chronic radiation proctitis is characterized by obliterative endarteritis and
submucosal fibrosis, which stiffens the rectum and impairs its compliance, resulting in urgency and fecal incontinence.
Chronic tissue hypoxia results in neovascularization and telangiectasia formation, which are prone to hemorrhage.

162. Gastrointestinal Hemorrhage Angiodysplasias in the gastrointestinal (GI) tract are a common source of
GI bleeding. Bleeding from angiodysplasias may be triggered by underlying aortic stenosis, which is associated with low
levels of von Willebrand factor multimers; this glycoprotein is often destroyed when it passes through the damaged valve
at high velocity.
163. Rectal Prolapse Rectal prolapse is characterized by intermittent protrusion of the rectum through the
anal canal; symptoms usually worsen with maneuvers that increase intra-abdominal pressure (e.g. defecation, Valsalva).
It is usually diagnosed in women age > 40 with risk factors that include multiparity, vaginal delivery, and chronic
constipation. Symptomatic patients should be referred for surgical intervention.

164. Polyarteritis Nodosa Polyarteritis nodosa is marked by segmental, transmural inflammation of

medium-sized arteries, which leads to luminal narrowing, thrombosis, and organ ischemia. The kidneys (e.g. renal
infarction) and gastrointestinal tract (e.g. mesenteric ischemia, bowel perforation) are often affected. Mesenteric
angiography typically reveals multiple arteries with microaneurysms, irregular luminal narrowing, and distal occlusions.

165. Volvulus Cecal volvulus occurs when the cecum and ascending colon twist on their mesentery,
forming a closed-loop obstruction. Progressive abdominal pain and distension, along with nausea/vomiting, are typical.
Abdominal x-ray may reveal a large, dilated loop of colon.

166. Volvulus Sigmoid volvulus often presents as slowly progressive abdominal discomfort/distension
in an elderly patient and a 'coffee bean'-shaped dilated loop of colon on abdominal x-ray. Patients without perforation or
 peritonitis can undergo flexible sigmoidoscopy to reduce the twisted segment and avoid emergency surgery.

167. Primary Sclerosing Cholangitis Primary sclerosing cholangitis is often diagnosed in asymptomatic
individuals with high alkaline phosphatase and γ-glutamyl transpeptidase levels (cholestatic pattern). Magnetic
resonance cholangiopancreatography findings of multifocal intrahepatic and extrahepatic biliary strictures with
segmental dilations are diagnostic. A colonoscopy is recommended at the time of diagnosis because many patients also
have inflammatory bowel disease.

168. Primary Sclerosing Cholangitis Primary sclerosing cholangitis is characterized by fibrosis and stricturing
of the medium and large intra- and extrahepatic bile ducts, promoting cholestasis and acute cholangitis. It occurs most
commonly in men and is strongly associated with ulcerative colitis.

169. Ovarian Cancer Alarm features for constipation include acute onset at an older age, weight loss, and
hematochezia. Ovarian cancer has nonspecific symptoms (e.g. lower abdominal pain, bloating, early satiety,
constipation). Therefore, older women (e.g. postmenopausal, age > 50) with new-onset abdominal pain and/or
concerning gastrointestinal symptoms, ovarian cancer should be considered.

170. Irritable Bowel Syndrome Irritable bowel syndrome presents with recurrent abdominal pain
related to defecation associated with episodes of diarrhea and/or constipation. Colonoscopy is required to rule out
malignancy in patients age > 50 with new-onset symptoms and in those with alarm features (e.g. gastrointestinal
bleeding, iron deficiency anemia).

171. Ascites Chronic pancreatitis occurs most commonly in patients with chronic alcohol use disorders and
results in postprandial epigastric pain. Pancreatic ascites results from damage to the pancreatic duct with leakage of
pancreatic juice into the peritoneal space. Paracentesis findings include serosanguinous or yellow fluid with high
amylase, high total protein, and low serum-ascites albumin gradient.

172. Ascites Persistently bloody ascites after multiple diagnostic paracenteses is concerning for an underlying
malignancy. Hepatocellular carcinoma is the most common cause, although bloody ascites can also occur with peritoneal
metastases from distant primary sites (e.g. ovaries, prostate). Cytologic analysis of the ascitic fluid can help identify the
primary tumor.
173. Hemobilia Hemobilia (bleeding into the biliary tract) is a rare cause of upper gastrointestinal
bleeding that usually occurs as a complication of hepatic or biliopancreatic procedures. It presents with right upper
quadrant pain, jaundice, and upper gastrointestinal bleeding.

174. Ascariasis Ascariasis typically affects patients with recent travel from endemic regions (e.g. Asia,
Africa, South America). It is often asymptomatic but may cause pulmonary (e.g. cough, eosinophilic pneumonitis) or
intestinal (e.g. abdominal pain, nausea/vomiting, malnutrition) manifestations. Complications include obstruction of the
small bowel or hepatobiliary tree (e.g. cholangitis, pancreatitis). Treatment includes albendazole or mebendazole.

175. Tracheoesophageal Fistula Tracheoesophageal fistula with esophageal atresia presents shortly after
birth with copious oral secretions and choking, coughing, and/or vomiting with feeding. Diagnosis can be confirmed by
inserting a nasogastric tube, which encounters resistance at the proximal esophageal pouch.

176. Gastrointestinal Hemorrhage Occult gastrointestinal bleeding usually presents with unexplained iron
deficiency anemia and/or a positive fecal occult blood test. Initial workup includes colonoscopy and upper endoscopy;
small bowel evaluation (e.g. video capsule endoscopy, deep enteroscopy) may be required if initial tests are unrevealing.
The presence of hemorrhoids should not preclude endoscopic evaluation.

177. Transplant Rejection Acute cellular rejection typically occurs within the first 3 months after liver
transplant and can present with fevers, malaise, and a rise in aminotransferases, bilirubin, and alkaline phosphatase.
Liver biopsy is diagnostic, demonstrating mixed inflammatory infiltration of the portal tracts, interlobular bile duct
 destruction, and endotheliitis. Most patients can be treated successfully with high-dose corticosteroids.

178. Zenker Diverticulum Impaired relaxation of the cricopharyngeus muscle during swallowing may lead
to the formation of a Zenker diverticulum, which is seen on contrast swallow study as a pouch posterior to the
esophagus. Treatment is surgical with cricopharyngeal myotomy with or without diverticulectomy.

179. Blunt Abdominal Trauma Rapid compression of the bowel during blunt abdominal trauma can
cause a perforated viscus. When viscus perforation occurs within the retroperitoneum (e.g. duodenal tear), classic
symptoms and signs (e.g. fever, diffuse abdominal pain) may be delayed. Retroperitoneal free air may be present on
abdominal imaging.

180. Colorectal Polyps And Cancer Sigmoidoscopy is an effective tool for evaluating lesions in the distal
colon but does not visualize the right colon. Patients with left-sided adenomas or adenocarcinomas detected on
sigmoidoscopy have increased risk for synchronous neoplasia on the right side and require visualization of the entire
colon with colonoscopy.

181. Refeeding Syndrome Refeeding syndrome occurs after the reintroduction of nutrition in patients with
chronic malnourishment. Clinical manifestations include hypophosphatemia and other electrolyte abnormalities, muscle
weakness, arrhythmias, and congestive heart failure.

182. Perforated Viscus Free perforation of the gastrointestinal tract in the setting of ongoing
inflammation (e.g. diverticulitis) often causes a classic pain sequence: sudden, severe pain (perforation) followed by
temporary relief (decompression) and then generalized, constant pain (peritonitis). Abdominal imaging typically shows
intraperitoneal free air.

183. Pancreatic Cancer Most pancreatic cysts are benign and can be managed conservatively (e.g.
surveillance imaging); however, some carry a risk for malignant transformation. Cysts with high-risk features (large size,
solid components or calcifications, main pancreatic duct involvement, thickened or irregular cyst wall) require further
evaluation with endoscopic ultrasound-guided biopsy and possibly surgical resection.

184. Perforated Viscus Small bowel obstruction can be complicated by bowel perforation. Free air on x-
ray and clinical signs of peritonitis should prompt emergent surgical exploration.

185. Volvulus Sigmoid volvulus occurs when a segment of sigmoid colon twists on its mesentery,
forming a closed-loop obstruction that often appears on abdominal x-ray as a dilated, inverted, U-shaped loop ('coffee
bean' sign). Chronic constipation and colonic dysmotility are risk factors.

186. Compartment Syndrome Decreased urine output and high peak inspiratory pressures in the
setting of a tensely distended abdomen are concerning for abdominal compartment syndrome (i.e. intra-abdominal
hypertension causing organ dysfunction). Bladder pressure measurement can estimate intra-abdominal pressure.

187. Enteral Nutrition Enteral nutrition, when feasible, is the optimal form of nutrition for critically ill
patients and has multiple clinical benefits (e.g. reduction in infections, maintenance of gut integrity) when initiated early
(i.e. < 48 hr).
188. Pancreatic Cancer Gastric outlet obstruction presents with intractable nausea and vomiting, early
satiety, and weight loss. Most cases are caused by malignancy, most commonly from pancreatic adenocarcinoma with
gastric or duodenal invasion. Pancreatic adenocarcinoma can also cause unexplained hyperglycemia resulting from islet
cell destruction.
189. Inflammatory Bowel Disease Patients with severe Crohn disease, especially those who have required
intestinal surgery in the past, are at high risk for future complications and often need aggressive management with
biologic and/or immunomodulator therapy. Smoking is strongly associated with increased severity and progression of
Crohn disease and should be avoided in these patients.
190. Ischemic Hepatitis Ischemic hepatitis, characterized histologically by zone 3-predominant
hepatocyte necrosis, occurs in the setting of global hypoperfusion and/or hypoxemia. Common causes include cardiac
insults (e.g. myocardial infarction, unstable arrhythmias), respiratory failure, hypovolemia, and septic shock. Patients
immediately develop severe aminotransferase elevations with bilirubin levels remaining unaffected or rising a few days
later.
191. Bowel Obstruction Severe, uncontrolled inflammation in Crohn disease can lead to a fibrotic
stricture of the small bowel with small bowel obstruction (SBO); smoking and young age (< 30) at diagnosis increase the
risk of such disease progression. Fibrotic stricture with SBO presents with bilious emesis, severe abdominal pain, and
inability to pass flatus and/or stool. Treatment usually requires surgical removal of the strictured portion of small bowel.

192. Inflammatory Bowel Disease Both Crohn disease and ulcerative colitis present with chronic diarrhea,
abdominal pain, anemia, and elevated inflammatory markers. Colonoscopy with biopsies is the test of choice for
diagnosis because it can distinguish between characteristic findings of Crohn disease (e.g. cobblestone appearance, skip
lesions, deep ulcerations, transmural inflammation, granulomas) and those of ulcerative colitis (e.g. continuous, shallow
ulcerations limited to the mucosa/submucosa, pseudopolyps).

193. Mesenteric Ischemia Sudden-onset, severe abdominal pain and anion gap metabolic acidosis should
raise suspicion for acute mesenteric ischemia. Most cases arise in the setting of thromboembolism (e.g. atrial fibrillation).
Diagnosis is generally made with CT mesenteric angiography.

194. Ogilvie Syndrome Acute colonic pseudo-obstruction (Ogilvie syndrome) typically presents with
severe abdominal distension, pain, vomiting, and obstipation. Common causes include electrolyte imbalance (e.g.
hypokalemia, hypomagnesemia) and factors that lead to autonomic disruption of the colon (e.g. major surgery,
neurologic disease, anticholinergic medication). The diagnosis is made by CT scan showing colonic dilation without
anatomic obstruction, and treatment involves bowel rest and colonic decompression, sometimes aided by intravenous
neostigmine.
195. Bariatric Surgery Patients who undergo Roux-en-Y gastric bypass are at risk for multiple vitamin
deficiencies. Fat-soluble vitamins and vitamin B12 deficiency are most common, but vitamin C deficiency can occur in the
setting of poor postoperative diet. Vitamin C deficiency is associated with ecchymosis, petechiae, poor wound healing,
perifollicular hemorrhage, coiled hairs, and gingivitis; platelet count, prothrombin time, and partial thromboplastin time
will be normal.
196. Biliary Atresia Biliary atresia is a neonatal disorder in which extrahepatic bile ducts develop progressive
fibrosis. Patients have jaundice, pale stools, and a small or absent gallbladder. Laboratory findings include direct
hyperbilirubinemia, normal reticulocyte count, and elevated γ-glutamyl transpeptidase.

197. Bariatric Surgery Anastomotic leak is a serious postoperative complication that can present with
fever, abdominal pain, tachypnea, and tachycardia, usually within the first week after bariatric surgery. The diagnosis is
best confirmed by oral contrast-enhanced imaging (either abdominal CT scan or upper gastrointestinal series), and
treatment requires urgent surgical repair.

198. Splenic Abscess Splenic abscess is a rare, life-threatening complication of bacteremia from a distant
infection (e.g. infective endocarditis, cholecystitis). Manifestations generally include persistent high fever and tender
splenomegaly. Diagnosis is made with CT scan of the abdomen; antibiotic therapy and splenectomy are generally
required.
199. Spleen Rupture Atraumatic splenic rupture is an uncommon but life-threatening complication of
hematologic malignancy, infection, and systemic inflammatory disease, and anticoagulation increases the risk. Patients
develop acute abdominal pain, shock, and anemia. Peritonitis and left shoulder pain may also be present.

200. Chronic Pancreatitis A pancreaticopleural fistula (between the pancreatic duct and the pleural space)
resulting in an amylase-rich exudative pleural effusion occurs most commonly as a result of acute or chronic pancreatitis.
Management includes bowel rest to promote fistula closure; endoscopic retrograde cholangiopancreatography may be
required.
201. Pancreatic Cancer Approximately 25% of pancreatic cancer is heralded by a recent (< 2 years)
diagnosis of diabetes mellitus. Although screening for pancreatic cancer is not recommended for patients with new-
onset diabetes mellitus, those who have symptoms (e.g. constant abdominal pain, weight loss) of pancreatic cancer
should undergo abdominal CT scan.

202. Pancreatic Cancer The most common symptom of pancreatic cancer is insidious, continuous
midepigastric pain that often radiates to the flanks or back and is sometimes worse with eating and lying down. CT scan
of the abdomen is the first-line test for suspected pancreatic cancer.

203. Rectal Prolapse Rectal prolapse is characterized by intermittent protrusion of the rectum (i.e.
erythematous mass with concentric rings) through the anal orifice. It is often associated with fecal incontinence,
constipation, and/or mucous discharge. Rectal prolapse is most common in women age > 40. Risk factors include
multiparity, vaginal delivery, pelvic surgery, pelvic floor dysfunction, chronic constipation or straining, dementia, and
stroke.
204. Esophageal Cancer Esophageal dysphagia is characterized by a sensation of food 'sticking' in the
esophagus; in older patients, esophageal malignancy is a common cause. Esophageal malignancy classically presents with
progressive solid-food dysphagia; retrosternal pain and weight loss are also common. Upper endoscopy is the test of
choice to evaluate dysphagia.

205. Esophagitis Eosinophilic esophagitis usually presents as intermittent solid food dysphagia and most
commonly affects younger men with atopic conditions. Untreated disease can cause esophageal stricture and food
impaction. Management includes dietary therapy (e.g. allergen avoidance, elimination diet), proton-pump inhibitors, and
topical glucocorticoids (e.g. fluticasone, budesonide).

206. Blunt Abdominal Trauma Blunt trauma that rapidly compresses the upper abdomen against the
vertebral column can injure the pancreas. Pancreatic injury can be difficult to diagnose immediately following trauma;
persistent abdominal discomfort or nausea, increasing amylase, or peripancreatic fluid collection should raise suspicion
for an undiagnosed injury.

207. Blunt Abdominal Trauma Rapid compression of the duodenum against the vertebral column
during blunt abdominal trauma may result in a duodenal hematoma. Hematoma expansion can progressively obstruct
the duodenal lumen, causing a delayed (24-48 hr) presentation of worsening emesis. CT scan confirms the diagnosis.

208. Esophageal Rupture Effort rupture of the esophagus (Boerhaave syndrome) can occur with vomiting
and may cause unilateral pleural effusion from leaked esophageal contents. Confirmation with esophagography or CT
scan using water-soluble contrast should prompt emergent surgical consultation.

209. Esophageal Rupture Blunt thoracic trauma can cause a sudden increase in intraesophageal pressure
sufficient to rupture the esophagus. If gastrointestinal contents leak from the esophagus into the pleural space, pleural
effusion results, and fluid analysis typically reveals unusual color (e.g. green), low pH, and high amylase.

210. Esophageal Rupture Esophageal perforation is a life-threatening complication of esophageal

instrumentation. Clinical presentation may include severe chest/back pain, fever, and a widened mediastinum on chest
x-ray. Water-soluble contrast esophagography can confirm the diagnosis.

211. Cholangitis Acute cholangitis should be suspected in a patient with gallstone pancreatitis who also
has fevers, right upper quadrant pain, jaundice, altered mental status, and hypotension. Endoscopic retrograde
cholangiopancreatography is required to relieve the biliary obstruction and prevent serious infectious complications.

212. ERCP Acute pancreatitis is the most common complication after endoscopic retrograde
cholangiopancreatography, and typically presents with abdominal pain with radiation to the back, nausea, and vomiting.
Lipase and amylase levels will rise several hours after symptom onset whereas CT scans can be normal for up to 48
hours.
213. Gastric Cancer Gastric cancer is common in those from Eastern Asia, Eastern Europe, and South
America. It generally presents with progressive epigastric pain and weight loss. Friable tumor vessels can bleed into the
stomach lumen, leading to iron deficiency anemia. Metastasis to the liver can result in hepatomegaly and elevated
transaminases and alkaline phosphatase.

214. Gastric Cancer Gastric cancer is endemic to Eastern Asia, Eastern Europe, and the Andean portions of
South America due to diets high in salt-preserved food and nitroso compounds. Manifestations typically include weight
loss and chronic mid-epigastric pain that worsens with eating. Esophagogastroduodenoscopy is the initial test of choice
to establish the diagnosis.

215. Gallstone Disease Biliary colic occurs when the gallbladder contracts against a gallstone that
temporarily blocks the cystic duct. Classic symptoms include episodic postprandial right upper quadrant or epigastric
pain, nausea, and vomiting; however, vital signs, white blood cell count, and liver function studies remain normal. The
diagnosis is confirmed with an abdominal ultrasound demonstrating the presence of gallstones.

216. Cholecystitis Emphysematous cholecystitis is characterized by fever, right upper quadrant pain, and
gas in the gallbladder wall, surrounding tissue, or hepatobiliary system. It occurs when gas-forming organisms such as
Clostridium infect damaged or ischemic tissue but, unlike uncomplicated acute cholecystitis, it is a surgical emergency
and warrants immediate cholecystectomy.

217. Clostridium Difficile Infection Clostridioides (formerly Clostridium) difficile infections can occasionally
be complicated by toxic megacolon, which usually presents with severe systemic symptoms (e.g. high fever, tachycardia),
leukocytosis, abdominal distension, and significant colonic distension on abdominal radiograph. Suspicion is often raised
when a patient with C. difficile infection stops having diarrhea and symptoms clinically worsen.

218. Diverticular Disease Acute diverticulitis is common in older individuals and typically presents with
dull, left lower quadrant pain; nausea and vomiting; alteration in bowel habits; and (sometimes) irritative bladder
symptoms (e.g. dysuria, frequency) or sterile pyuria.

219. Cholangiocarcinoma Cholangiocarcinoma, a biliary tract epithelial malignancy, most often occurs in
those who have fibropolycystic liver disease or primary sclerosing cholangitis due to underlying ulcerative colitis. Most
cases present with subacute right upper quadrant pain, weight loss, and signs of biliary obstruction such as jaundice,
cholestatic liver enzyme pattern, and dilation of the intrahepatic or common bile duct.

220. Fistula In Ano Anorectal fistulas are most often due to rupture of a perianal abscess with formation of a
persistent sinus tract. Symptoms include pain with defecation and chronic discharge. Management requires surgical
intervention.
221. Hemorrhoids Thrombosis of an external hemorrhoid manifests as excruciating anorectal pain
exacerbated by sitting. Examination demonstrates a bluish (or purplish) bulge at the anal verge. Initial management
includes sitz baths, stool softeners, and topical anesthetics.

222. Paralytic Ileus Prolonged postoperative ileus, the delayed return of bowel function > 72 hours after
surgery, is typically self-resolving; therefore, management is conservative with bowel rest and serial examinations.

223. Hepatocellular Cancer Patients with cirrhosis are often unaware of the condition until they develop
complications. One major complication is hepatocellular carcinoma, a primary liver tumor that often presents with
decompensated liver failure, weight loss, and a palpable liver lesion. α-fetoprotein is elevated in ~50% of cases;
therefore, it can be a useful diagnostic clue but cannot be used to rule out the disease.

224. Hepatocellular Cancer Hepatocellular carcinoma usually arises due to chronic liver inflammation from
viral hepatitis, alcoholism, or environmental toxins. Incidence is greatest in regions that have high rates of hepatitis B and
C virus infection, such as Asia, Africa, and the Middle East. Approximately 50% of HCC cases are associated with dramatic
 elevations in α-fetoprotein.

225. Hepatocellular Cancer Hepatocellular carcinoma (HCC) is a common complication of cirrhosis, with a
risk of 1%-8% per annum in this population. Therefore, screening with abdominal ultrasound every 6 months is
recommended. Because HCC often presents with liver decompensation (e.g. new-onset ascites, variceal bleeding), this
condition should prompt abdominal ultrasound to evaluate for HCC.

226. Hepatic Adenomas Young women on prolonged oral contraception are at greatest risk for hepatic
adenoma. Although most lesions are benign and asymptomatic, life-threatening complications such as malignant
transformation or rupture can occur. Rupture should be suspected in the setting of sudden-onset, severe right upper
quadrant pain and signs of hemorrhagic shock.

227. Focal Nodular Hyperplasia Focal nodular hyperplasia is a benign liver lesion due to an aberrant
congenital artery. It is usually found incidentally in young women and is marked by the presence of a stellate central scar
and radiating fibrous bands.

228. Groin Hernias Femoral hernias are more common in elderly women and are more likely than inguinal
hernias to develop complications (e.g. incarceration, strangulation). Small bowel obstruction can occur and typically
presents with progressive abdominal pain, nausea/vomiting, high-pitched bowel sounds on examination, and distended
loops of bowel with air-fluid levels on x-ray.

229. Groin Hernias Femoral hernias (hernia located below inguinal ligament) protrude through the femoral
ring and usually present with a nontender, nonpulsatile bulge in the groin that grows in size with increased abdominal
pressure. Because the risk of incarceration with femoral hernias is high (due to narrow hernia orifice), patients with
asymptomatic femoral hernias are referred for early elective hernia repair. In contrast, asymptomatic inguinal hernias
(hernia located above inguinal ligament) can usually be managed with watchful waiting because hernia contents pass
through a wider orifice.

230. Wound Dehiscence And Evisceration Deep (fascial) wound dehiscences can result in exposure or
herniation (i.e. evisceration) of intra-abdominal organs (e.g. bowel), resulting in possible strangulation. Therefore,
patients with fascial dehiscence require emergency surgery.

231. Hemorrhoids Initial management of uncomplicated hemorrhoids includes increased intake of fluid and
fiber, reduction of fat and alcohol intake, and regular exercise. Additional measures may include phlebotonics, topical
hydrocortisone, astringents, and local anesthetics. Rubber band ligation and surgical hemorrhoidectomy are advised only
for patients with refractory symptoms or prolapsed hemorrhoids that cannot be reduced manually.

232. Liver Abscess Pyogenic liver abscess typically presents with fevers, right upper quadrant pain,
leukocytosis, and altered liver function tests. It can result from direct spread from the biliary tract or from hematogenous
seeding of distal infection, particularly those involving the portal system (e.g. diverticulitis). Diagnosis requires abdominal
imaging, and management includes blood cultures, antibiotics, aspiration, and drainage.

233. Hiatal Hernia Hiatal hernia is a common disorder that occurs when the contents of the abdominal
cavity herniate through the diaphragm into the thoracic cavity at the esophageal hiatus. Plain radiography typically
reveals a retrocardiac opacity (often with an air/fluid level) within the thoracic cavity. Asymptomatic sliding hiatal hernias
do not require further workup or intervention whereas patients with gastroesophageal reflux disease should be
medically managed.

234. Hiatal Hernia Paraesophageal hiatal hernias occur when the gastric fundus migrates into the thoracic
cavity; large defects can result in herniation of the surrounding stomach and intra-abdominal organs. Manifestations
include nausea and vomiting, postprandial fullness, dysphagia, and epigastric and/or chest pain. Chest imaging typically
reveals a retrocardiac air-fluid level within the thoracic cavity.
235. Inflammatory Bowel Disease Mild ulcerative colitis (UC) is defined as < 4 bowel movements a day,
intermittent hematochezia, normal inflammatory markers, and no anemia. First-line treatment is with 5-aminosalicylic
acid medications; suppositories or enemas are preferred in patients with UC limited to the rectosigmoid, whereas oral
therapy is used for more extensive disease.

236. Inflammatory Bowel Disease Erythema nodosum presents with tender, nonpruritic, erythematous, or
violaceous nodules measuring 2-3 cm and usually located on the shins. It has a strong association with inflammatory
bowel disease (IBD), especially Crohn disease, and its presence correlates with the degree of IBD activity.

237. Vitamin C Deficiency Scurvy (vitamin C deficiency) typically occurs in the setting of severe malnutrition
due to alcoholism, drug abuse, or psychiatric illness. Common manifestations include prominent cutaneous findings (e.g.
follicular hyperkeratosis, perifollicular hemorrhage, ecchymosis, petechiae), gingivitis (e.g. recessed gums that bleed
easily, dental caries), and impaired wound healing. Diagnosis is made with plasma or leukocyte vitamin C levels.

238. Perianal Abscess Occlusion of an anal crypt gland can lead to a bacterial infection and perianal
abscess formation. Perianal abscesses often present as tender, fluctuant, erythematous masses with fever and
progressively worsening pain. Anoreceptive intercourse and chronic constipation are among the risk factors for perianal
abscess development.

239. Intra-Abdominal Abscess Patients who receive a laparoscopic appendectomy are at much greater
risk for intra-abdominal abscess than those receiving laparotomy. Intra-abdominal abscess should be suspected when
fever and abdominal symptoms (e.g. pain, vomiting) return several days after an abdominal operation.

240. Obesity Bariatric surgery is indicated for patients with a BMI > 40 kg/m2 or those with a BMI > 35 kg/m2
and additional weight-related comorbidity. Weight-loss medication is indicated for patients with a BMI > 30 kg/m2 or
those with a BMI 25-29.9 kg/m2 and weight-related complications. Medication failure is not required for patients to
qualify for bariatric surgery; both interventions may be pursued concurrently.

241. Blunt Abdominal Trauma Patients with blunt abdominal trauma should be assessed for intra-
abdominal injury, beginning with Focused Assessment with Sonography for Trauma (FAST), a rapid, noninvasive
examination that can be performed at the bedside.

242. Chronic Pancreatitis Steatorrhea occurs due to fat malabsorption and generally presents with
voluminous, greasy, and foul-smelling stools that are difficult to flush. It is commonly caused by pancreatic exocrine
insufficiency (loss of digestive enzymes) in patients with chronic alcoholic pancreatitis. Alcohol cessation and pancreatic
enzyme supplementation can improve symptoms in such patients.

243. Gallstone Disease Total parenteral nutrition causes gallbladder stasis and predisposes to gallstone
formation and bile sludging, both of which may lead to cholecystitis.

244. Retroperitoneal Hematoma Anticoagulation with warfarin places patients at risk for hemorrhage.
Retroperitoneal hematoma may occur even without a supratherapeutic INR. Back pain and signs and symptoms of
hemodynamic compromise should raise suspicion for retroperitoneal hematoma.

245. Cholecystitis Acute cholecystitis presents with right upper quadrant pain, fever, and leukocytosis.
Patients with acute cholecystitis should be treated with laparoscopic cholecystectomy within 72 hours.

246. Pilonidal Disease Pilonidal disease most frequently affects males age 15-30, particularly obese
individuals, those with sedentary lifestyles or occupations, and those with deep gluteal clefts. The most common
presenting symptoms include a painful, fluctuant mass 4-5 cm cephalad to the anus in the intergluteal region with
associated mucoid, purulent, or bloody drainage.
247. Metastatic Liver Disease Multiple liver masses are much more likely to be the result of metastatic
disease than infectious causes or primary liver malignancy. Primary tumors of the gastrointestinal tract, lung, and breast
are the most common diseases causing liver metastases.

248. Paralytic Ileus Prolonged postoperative ileus is characterized by nausea, abdominal distension,
obstipation, and hypoactive bowel sounds that persist postoperatively. Opiates compound this problem by decreasing
gastrointestinal motility.

249. Anticoagulants Patients on warfarin who require urgent surgery with a high risk of bleeding, or those
who are experiencing significant hemorrhage, should receive prothrombin complex concentrate (PCC) and intravenous
vitamin K. If PCC is unavailable, fresh frozen plasma can be given.

250. Pancreatic Cancer Pancreatic cancer classically presents insidiously with a combination of constant
and gnawing epigastric pain that is frequently worse at night, anorexia with weight loss, and jaundice due to extrahepatic
biliary obstruction. A peptic duodenal ulcer typically causes periodic epigastric pain relieved by meals.

251. Blunt Abdominal Trauma Blunt abdominal trauma can cause gastrointestinal perforation in an
acute or a delayed (e.g. progression of bowel contusion, mesenteric ischemia) fashion. Confirmation of perforation (e.g.
intraperitoneal free air on imaging) should prompt emergent surgical exploration.

252. Blunt Abdominal Trauma The liver is one of the most commonly injured organs in blunt abdominal
trauma. Patients with severe liver laceration causing intra-abdominal hemorrhage may have shock and intraperitoneal
free fluid on Focused Assessment with Sonography for Trauma.

253. Gastric Outlet Obstruction Gastric outlet obstruction can be caused by many disease processes and
is characterized by early satiety, nausea, nonbilious vomiting, and weight loss. In a patient with a history of acid
ingestion, pyloric stricture is the most likely cause.

254. Perforated Viscus Peptic ulcer disease can be complicated by perforation, revealed as
intraperitoneal free air. Emergent surgical exploration is indicated for patients with severe symptoms and a systemic
inflammatory response.

255. Gallstone Disease Biliary colic occurs due to increased intra-gallbladder pressure that is created
when the gallbladder contracts against an obstructed cystic duct. The pain is exacerbated by fatty meals, usually lasts less
than 6 hours, and resolves completely between episodes. There is no fever, abdominal tenderness on palpation, or
leukocytosis.
256. Bowel Obstruction Complete small bowel obstruction usually presents with nausea, vomiting,
abdominal bloating, and dilated loops of bowel on abdominal x-ray. Adhesions, typically postoperative, are the most
common etiology.

257. Esophageal Rupture Effort rupture of the esophagus (Boerhaave syndrome) may occur during
protracted vomiting. Chest x-ray may show leaked esophageal fluid collecting in the mediastinum (mediastinal widening)
or pleural space (pleural effusion). Pleural fluid analysis may show low pH and very high amylase (> 2500 IU/L).
Confirmation with esophagography or CT scan using water-soluble contrast should prompt emergent surgical
consultation.
258. Appendicitis Patients who present with appendicitis > 5 days after the onset of symptoms have a high
incidence of perforation with abscess formation. They often have a contained abscess. If the patients are otherwise
stable, they may be treated with intravenous hydration, antibiotics, bowel rest, and interval appendectomy.

259. Zenker Diverticulum Diminished relaxation of the cricopharyngeus muscle during swallowing results
in increased intraluminal pressure in the hypopharynx. This may cause the mucosa to herniate, forming a Zenker
(pharyngoesophageal) diverticulum, which presents in patients age > 60 with dysphagia, halitosis, and regurgitation of
 undigested food.

260. Gastric Cancer In gastric adenocarcinoma, tumor stage at the time of diagnosis determines prognosis
and treatment options. A CT scan is the initial staging modality.

261. Anal Fissure Anal fissures present with pain and rectal bleeding on defecation. Treatment includes
increased fiber and fluid intake, stool softeners, sitz baths, and topical anesthetics and vasodilators (e.g. nifedipine,
nitroglycerin).
262. Zollinger-Ellison Syndrome Zollinger-Ellison syndrome should be suspected in patients with multiple
duodenal ulcers refractory to treatment or ulcers distal to the duodenum or associated with chronic diarrhea. In these
patients, inactivation of pancreatic enzymes by increased production of stomach acid may lead to malabsorption.

263. Colonic Ischemia Ischemic colitis is characterized by acute abdominal pain and lower
gastrointestinal bleeding. It typically follows an episode of hypotension and most commonly affects arterial watershed
areas at the splenic flexure and rectosigmoid junction. CT scan may show a thickened bowel wall. Colonoscopy can
confirm the diagnosis.

264. Dumping Syndrome Dumping syndrome is a common postgastrectomy complication characterized by

gastrointestinal (e.g. nausea, diarrhea, abdominal cramps) and vasomotor (e.g. palpitations, diaphoresis) symptoms. The
symptoms can be controlled with dietary modification and usually diminish over time.

265. Colonic Ischemia Ischemic colitis is a common complication of vascular surgery, as patients are
often older and have extensive underlying atherosclerosis. CT imaging can show thickening of the bowel wall.
Colonoscopy shows cyanotic mucosa and hemorrhagic ulcerations.

266. Blunt Abdominal Trauma Rapid compression of the duodenum against the vertebral column
during blunt abdominal trauma may result in a duodenal hematoma. Affected patients commonly have epigastric pain
and emesis 24-48 hours postinjury because the hematoma expands to obstruct the duodenal lumen. CT scan confirms
the diagnosis.
267. Inflammatory Bowel Disease Patients with inflammatory bowel disease (IBD) are at highest risk of
developing toxic megacolon (TM) early in the disease, sometimes at initial presentation. Patients with IBD-induced TM
should receive intravenous corticosteroids.

268. Zinc Deficiency Risk factors for trace mineral deficiency include malabsorption, bowel resection, poor
nutritional intake, and dependence on parenteral nutrition. Clinical manifestations of zinc deficiency include
hypogonadism, impaired taste, impaired wound healing, alopecia, and skin rash with perioral involvement.

269. Porcelain Gallbladder Porcelain gallbladder is usually diagnosed on abdominal imaging showing a
calcified rim in the gallbladder wall with a central bile-filled dark area. It is associated with an increased risk for
gallbladder adenocarcinoma and usually requires cholecystectomy.

270. Small Intestinal Bacterial Overgrowth Small intestinal bacterial overgrowth (SIBO) is characterized by
bloating, flatulence, and watery diarrhea; malabsorption and nutritional deficiencies may also occur. SIBO is a common
complication of gastric bypass procedures. Conditions that alter intestinal motility (e.g. systemic sclerosis, diabetes
mellitus), anatomy (e.g. strictures), or gastric/pancreatic secretions (e.g. atrophic gastritis, chronic pancreatitis) also
predispose to SIBO.

271. Zollinger-Ellison Syndrome Gastrinoma (Zollinger-Ellison syndrome) should be suspected in patients

with multiple stomach ulcers and thickened gastric folds on endoscopy. The diagnosis is strongly suggested by a fasting
serum gastrin level > 1000 pg/mL. Patients with nondiagnostic serum gastrin levels should be evaluated with a secretin
stimulation test.
272. Diverticular Disease Colovesical fistula is most commonly due to diverticular disease and presents
with pneumaturia, fecaluria, or findings consistent with urinary tract infection. Abdominal CT scan with oral or rectal (not
intravenous) contrast can confirm the diagnosis by showing contrast material in the bladder with thickened colonic and
vesicular walls.
273. Diverticular Disease CT-guided percutaneous drainage is recommended for complicated diverticulitis
with abscess formation. Surgical drainage can be attempted if percutaneous drainage fails.

274. Psoas Abscess Psoas abscess commonly presents subacutely with fever and lower abdominal or flank
pain radiating to the groin. The ‘psoas sign', abdominal pain with hip extension, can often be detected on examination.
CT scans are required to confirm the diagnosis, and drainage with antibiotics is the mainstay of therapy.

275. Paralytic Ileus Ileus is commonly due to abdominal surgery but can also be seen in
retroperitoneal/abdominal hemorrhage, intra-abdominal inflammation (e.g. pancreatitis), intestinal ischemia, and
electrolyte abnormalities. Signs and symptoms include nausea, vomiting, abdominal distension, obstipation, and
hypoactive or absent bowel sounds. Abdominal radiography classically reveals uniformly distended, gas-filled loops of
both the small and the large intestines.

276. Perforated Viscus Sudden-onset, severe abdominal pain with peritonitis and subdiaphragmatic free
air on upright chest x-ray is a classic presentation of perforated viscus (e.g. perforated peptic ulcer).

277. Appendicitis The evaluation of patients with suspected appendicitis (e.g. modified Alvarado score > 4)
now includes imaging, which can visualize the appendix (e.g. normal vs nonperforated or perforated appendicitis) and
direct management. CT scan of the abdomen and pelvis is the recommended imaging study in nonpregnant adults.

278. Gilbert Syndrome Gilbert syndrome, the most common inherited disorder of bilirubin
glucuronidation, is characterized by recurrent episodes of mild jaundice precipitated by stressors (e.g. infection, fasting,
vigorous exercise, surgery). With the exception of elevated unconjugated bilirubin, liver function test results and
complete blood counts are normal.

279. Gallstone Disease Sphincter of Oddi dysfunction is a functional biliary disorder due to dyskinesia or
stenosis of the sphincter of Oddi. Patients experience recurrent, episodic pain in the right upper quadrant or epigastric
region, with corresponding elevations in aminotransferases and alkaline phosphatase. Opioid analgesics (e.g. morphine)
may cause sphincter contraction and precipitate symptoms.

280. Pancreatic Cancer Pancreatic cancer can be due to hereditary (e.g. first-degree relative with
pancreatic cancer, hereditary pancreatitis) or environmental (e.g. cigarette smoking, obesity) risk factors. Cigarette
smoking is the most consistent reversible risk factor for pancreatic cancer.

281. Pancreatic Cancer Pancreatic cancer in the body or tail of the organ may present with constant,
progressive back pain that is worse at night and when supine. Because this is a referred pain, back/neurologic
examinations and radiographic imaging are generally normal. An abdominal CT scan is usually diagnostic.

282. Metastatic Liver Disease The most common malignancy of the liver is metastasis from another
primary source.
283. Cholecystitis Acute acalculous cholecystitis is an acute inflammation of the gallbladder in the absence
of gallstones that is most commonly seen in hospitalized and critically ill patients.

284. Gallstone Disease Postcholecystectomy syndrome is persistent abdominal pain or dyspepsia either
postoperatively (early) or months to years (late) after cholecystectomy. Etiologies include biliary (e.g. retained common
bile duct, cystic duct stone) or extra-biliary (e.g. pancreatitis, peptic ulcer disease) causes. Abdominal imaging (e.g.
ultrasound) followed by direct visualization (e.g. endoscopic retrograde cholangiopancreatography, magnetic resonance
cholangiopancreatography) can establish the diagnosis and guide therapy toward the causative factor.
285. Cholecystitis Emphysematous cholecystitis is a life-threatening form of acute cholecystitis that occurs
more commonly in patients with immunosuppression (e.g. diabetes) or vascular disease. It arises due to infection of the
gallbladder wall with gas-forming bacteria and requires emergency cholecystectomy.

286. Pancreatic Cancer The presentation of pancreatic cancer is dependent on tumor location; tumors in
the pancreatic head often present with painless obstructive jaundice, whereas those in the body or tail often cause
abdominal pain without jaundice. Although ultrasound is the imaging test of choice to evaluate a jaundiced patient, a CT
scan of the abdomen is indicated for those with a nondiagnostic ultrasound or to evaluate for suspected malignancy in a
nonjaundiced patient.

287. Acute Pancreatitis Gallstone pancreatitis should be suspected in patients who have evidence of
pancreatitis with alanine aminotransferase levels > 150 U/L. Early cholecystectomy is indicated in all patients with
gallstone pancreatitis who are medically stable enough to undergo surgery.

288. Hepatic Adenomas Hepatic adenoma is a benign tumor most often seen in young and middle-age
women who take oral contraceptives. Possible long-term complications include progressive growth, rupture, and
malignant transformation.

289. Gallstone Disease Asymptomatic gallstones should not be treated. Laparoscopic cholecystectomy
is the treatment of choice for symptomatic gallstone disease.

290. Acute Pancreatitis Gallstones and chronic alcohol abuse are the most common causes of acute
pancreatitis. Abdominal ultrasound is the most sensitive and specific imaging study to detect gallstones and should be
performed in all patients with suspected gallstone-induced pancreatitis.

291. Gastrointestinal Hemorrhage The first step in the treatment of acute upper gastrointestinal bleeding is
to establish vascular access with 2 large-bore intravenous catheters to initiate resuscitation with intravenous fluids.

292. Cholecystitis Acute cholecystitis usually presents with sudden onset of right upper quadrant
abdominal pain, fever, vomiting, and leukocytosis. The primary inciting event is a gallstone obstructing the cystic duct
with subsequent inflammation and infection.

293. Gallstone Disease Gallstone ileus results from small bowel obstruction due to a gallstone that has
passed through a biliary-enteric fistula. As the stone advances it may cause 'tumbling' obstruction before ultimately
causing complete obstruction. Treatment involves surgical removal of the stone and cholecystectomy.

294. Acute Pancreatitis Pancreatic pseudocyst is an encapsulated area (comprised of enzyme-rich fluid,
tissue, and debris) that causes an inflammatory response. Diagnosis is confirmed by abdominal imaging. Expectant
management is preferred initially in patients with minimal or no symptoms and without complications. Endoscopic
drainage is typically reserved for patients with significant symptoms (e.g. abdominal pain, vomiting), infected
pseudocyst, or evidence of pseudoaneurysm.

295. Mesenteric Ischemia Acute mesenteric ischemia is commonly due to abrupt arterial occlusion from
cardiac embolic events (e.g. ventricular thromboembolism). If ischemia is prolonged, patients may develop more focal
findings due to infarction, perforation, or peritonitis. Laboratory studies typically show leukocytosis, elevated
hemoglobin, elevated amylase, and metabolic acidosis.

296. Pancreatic Cancer Painless jaundice in a patient with conjugated hyperbilirubinemia and markedly
elevated alkaline phosphatase should raise concern for biliary obstruction due to pancreatic or biliary cancer. Other
common causes of biliary obstruction include choledocholithiasis and benign biliary strictures.

297. Pancreatic Cancer Trousseau syndrome is a hypercoagulability disorder presenting with recurrent
and migratory superficial thrombophlebitis at unusual sites (e.g. arm, chest area). It is usually associated with an occult
 visceral malignancy such as pancreatic (most common), stomach, lung, or prostate carcinoma.

298. Esophageal Cancer Diagnosis of esophageal cancer requires esophageal endoscopy with biopsy.
Young, low-risk patients with undetermined esophageal symptoms may start with barium esophagram, but those who
are age > 50 or with alarm symptoms (e.g. weight loss, gross or occult bleeding, early satiety) should proceed directly to
endoscopy.
299. Umbilical Hernia A congenital umbilical hernia is typically soft and reducible and does not require
intervention. These hernias usually close spontaneously by age 5.

300. Esophageal Rupture Effort rupture of the esophagus (Boerhaave syndrome) can occur with vomiting.
Leakage of esophageal air through the full-thickness perforation may cause pneumomediastinum, evidenced by
suprasternal crepitus on examination. Confirmation with esophagography or CT scan using water-soluble contrast should
prompt emergent surgical consultation.

301. Esophageal Rupture Esophageal perforation is a life-threatening complication of endoscopy. Clinical

presentation may include severe chest/back pain, systemic inflammatory response, and pleural effusion from leaked
esophageal contents. Contrast esophagography is the best test to confirm the diagnosis.

302. Blunt Abdominal Trauma The spleen is one of the most commonly injured organs in blunt
abdominal trauma. Patients with severe splenic laceration causing intra-abdominal hemorrhage may have shock and
intraperitoneal free fluid on Focused Assessment with Sonography for Trauma.

303. Bowel Obstruction Immediate surgical intervention is indicated for patients with intestinal
obstruction who develop clinical or hemodynamic instability, fail to improve after initial conservative measures, and/or
develop symptoms or signs of ischemia or necrosis.

304. Cholecystitis Acalculous cholecystitis occurs in critically ill patients. The clinical presentation may be
similar to calculous cholecystitis, though assessment may be difficult due to the underlying illness. Imaging studies show
gallbladder wall thickening and distension and pericholecystic fluid. The emergency treatment of choice is antibiotics and
percutaneous cholecystostomy, followed by cholecystectomy when the medical condition stabilizes.

305. Zenker Diverticulum Recurrent pneumonia in an elderly patient with dysphagia and regurgitation of
undigested food raises concern for a Zenker diverticulum, which may occasionally present with a palpable mass. A
swallow study with contrast esophagography can be used to confirm the diagnosis.

306. Pancreatic Cancer Tumors in the head of the pancreas can present with weight loss, jaundice, and a
nontender, distended gallbladder (e.g. Courvoisier sign) on examination. Imaging can demonstrate dilation of both the
intra- and extrahepatic bile ducts as well as the pancreatic duct (i.e. double duct sign).

307. Inflammatory Bowel Disease Diagnosis of toxic megacolon requires radiographic evidence (e.g.
abdominal CT scan) of colonic dilation > 6 cm, along with manifestations of systemic toxicity (e.g. fever, leukocytosis,
hemodynamic instability).

308. Diverticular Disease Abdominal CT scan is the best diagnostic test for diagnosing acute diverticulitis
and differentiating it from other causes of abdominal pain.

309. Mallory-Weiss Syndrome Mallory-Weiss tear occurs due to a sudden increase in intra-abdominal
pressure (e.g. retching), leading to a mucosal tear and hematemesis. The diagnosis can be confirmed on endoscopy.
Bleeding stops spontaneously in most patients, but those with ongoing bleeding can be treated endoscopically.

310. Mesenteric Ischemia Acute mesenteric ischemia classically presents with acute-onset, severe,
midabdominal pain out of proportion to physical examination findings. Progression to bowel infarction causes focal pain,
 peritoneal signs, rectal bleeding and sepsis.

311. Surgical Wound Infection Prophylactic antibiotics reduce surgical site infections and are indicated
when there is a high risk of infection or when infection would lead to significant morbidity/mortality. Patients
undergoing clean procedures (i.e. without infection or viscus entry) should receive coverage against gram-positive skin
flora, ideally with a first- or second-generation cephalosporin (e.g. cefazolin) or, alternatively, with vancomycin or
clindamycin.
312. Hypovolemia Hemorrhagic shock is the most common type of shock in trauma patients. Areas where
large amounts of blood can be lost (or hidden) are ‘the floor' (external bleeding) ‘and 4 more': chest, abdomen,
pelvis/retroperitoneum, and thigh.

313. Thermal Burn Burn victims frequently develop intravascular volume depletion and require aggressive
resuscitation with crystalloid solutions. Lactated Ringer solution, a balanced fluid, is preferred because it contains near-
physiologic levels of electrolytes and includes a buffer that helps correct acidosis and maintain normal blood pH. Normal
saline is associated with the development of hyperchloremic metabolic acidosis.

314. Blunt Abdominal Trauma For patients with blunt abdominal trauma who are hemodynamically
unstable, emergent laparotomy is indicated in the presence of peritonitis or intraperitoneal free fluid on Focused
Assessment with Sonography for Trauma (FAST) examination.

315. Blunt Abdominal Trauma Splenic injury, one of the most common intra-abdominal complications
of blunt abdominal trauma (BAT), should be suspected in any patient with BAT and evidence of hemorrhage.
Hemodynamically stable patients with a negative ultrasound evaluation but high-risk features should undergo CT
imaging.
316. Amputation In cases of traumatic amputation, the amputated part should be transported by
wrapping it in saline-moistened gauze, sealing it in a plastic bag, and placing the bag in a bath of ice water. Cooling of the
amputated part prolongs the window for replantation.

317. Blunt Thoracic Trauma Persistent pneumothorax and large air leak despite tube thoracostomy in the
setting of blunt chest trauma suggest tracheobronchial rupture. Bronchoscopy can confirm the diagnosis prior to
operative repair.

318. Penetrating Abdominal Trauma Patients with penetrating abdominal trauma and hemodynamic
instability, peritonitis, evisceration, or impalement should undergo immediate exploratory laparotomy.

319. Spinal Cord Injury Patients with cervical spine injuries are at risk of respiratory compromise.
Orotracheal intubation with manual stabilization of the cervical spine is recommended for initial airway management.

320. Penetrating Thoracic Trauma Any penetrating wound below the fourth thoracic dermatome (i.e.
nipple level) can involve the intra-abdominal organs. Patients with penetrating abdominal trauma and any of the
following indications - hemodynamic instability, peritonitis, evisceration - should undergo immediate exploratory
laparotomy.
321. Traumatic Brain Injury All trauma patients should be triaged using the Glasgow coma scale (GCS), which
can predict the severity and prognosis of coma, during the primary survey. The GCS assesses the patient's ability to open
his/her eyes, motor response, and verbal response.

322. Blood Transfusion Blood products should be administered early in patients with signs of
hemorrhagic shock. They should be administered in a ratio of 1:1:1 (fresh frozen plasma/packed red blood
cells/platelets) to reduce coagulopathy, a leading contributor to mortality in trauma patients.

323. Hypovolemic Shock Large-volume crystalloid resuscitation increases coagulopathy, hypothermia, and
mortality in trauma patients. Balanced resuscitation, which restricts crystalloid use and uses blood products to maintain
a blood pressure just sufficient for tissue perfusion (i.e. permissive hypotension) until hemorrhage is controlled, can
 decrease these adverse effects.

324. Hypovolemic Shock Blood transfusion should be initiated early in patients with hemorrhagic shock.
Group O, Rh D-negative blood (universal donor) should be transfused while waiting for type-specific blood to be
available.
325. Breast Mass The workup of a suspicious breast mass (e.g. unilateral, firm, fixed, causing nipple
retraction) is the same in men as in women: imaging (e.g. mammography, ultrasound) is performed first, followed by
tissue sampling (e.g. core biopsy).

326. Venous Thromboembolism Patients who inject drugs into the femoral vein can develop iliofemoral
deep venous thrombosis. This disorder is typically marked by unilateral leg edema, warmth, and erythema with evidence
of dilated superficial veins and increased calf/thigh diameter on examination.

327. Venous Thromboembolism Spontaneous upper extremity deep venous thrombosis most often
occurs in young, athletic men who lift weights or engage in activities that have repetitive overhead arm motions (e.g.
pitching a baseball game). It is marked by acute arm swelling, heaviness, and pain. Treatment generally requires
thrombolysis and/or 3 months of anticoagulation.

328. Venous Thromboembolism Peripherally inserted central catheters increase the risk of upper
extremity deep venous thrombosis. The risk is greatest in hospitalized patients, particularly those with malignancy or
other hypercoagulable state. Manifestations include arm swelling, erythema, and pain. The diagnosis is made with
duplex ultrasonography. Treatment with 3 months of anticoagulation is required.

329. Von Willebrand Disease Insufficient hemostasis is the most common cause of postoperative hematoma
in patients with no personal or family history of easy bleeding or bruising.

330. DIC Chronic disseminated intravascular coagulation is common in patients with mucin-producing
tumors (e.g. pancreatic cancer) due to periodic release of tissue factor into the bloodstream, which triggers low-grade
coagulation and fibrinolysis. Patients frequently have normal platelet counts and coagulation times but are at increased
risk for venous and arterial thrombosis and, to a lesser extent, mucocutaneous bleeding.

331. DIC Severe trauma increases the risk of disseminated intravascular coagulation, a consumptive
coagulopathy, due to the exposure of tissue factor and the release of procoagulant proteins and phospholipids.
Laboratory evaluation will reveal prolonged PT/PTT and thrombocytopenia. Patients usually develop signs of bleeding
(e.g. oozing from venipuncture/surgical sites) and organ damage (e.g. renal insufficiency).

332. Graft Versus Host Disease Acute graft-versus-host disease is a common complication of allogenic
hematopoietic stem cell transplantation. It arises when donor T-lymphocytes recognize antigens on host epithelial cells
as foreign and initiate a strong inflammatory response. Patients usually manifest symptoms within 100 days of
transplant, including a maculopapular rash; profuse, watery diarrhea; and signs of hepatobiliary inflammation.

333. Rectus Sheath Hematoma Rectus sheath hematomas are characterized by acute abdominal pain
with a palpable abdominal wall mass, often associated with anemia and leukocytosis. They usually occur due to rupture
of the inferior epigastric artery from blunt trauma or forceful abdominal contractions (e.g. severe coughing), particularly
in those receiving anticoagulation therapy.

334. Blood Transfusion Transfusion-related acute lung injury is a potentially fatal transfusion reaction,
presenting with acute dyspnea and hypoxia, bilateral pulmonary infiltrates, and possible hypotension. Management
involves transfusion cessation and respiratory supportive care.

335. Methemoglobinemia Acquired methemoglobinemia results from the oxidization of iron in

hemoglobin, which is most commonly due to topical anesthetic agents or dapsone. It presents with hypoxia, a
 characteristic pulse oximetry reading of ~85%, and a large oxygen saturation gap.

336. Heparin Induced Thrombocytopenia Heparin-induced thrombocytopenia (HIT) should be suspected in

patients on heparin who develop thrombocytopenia or thrombotic complications. In patients receiving heparin
subcutaneously (e.g. enoxaparin), a classic thrombotic complication is skin necrosis at the abdominal injection site. HIT is
treated by discontinuing all heparin products and initiating an alternate anticoagulant (e.g. argatroban, fondaparinux).

337. Venous Thromboembolism Major surgery is a significant risk factor for deep venous thrombosis
(DVT). At least 3 months of anticoagulation is recommended for provoked DVT. Stable patients can be treated with
anticoagulation as early as 48-72 hours after surgery. Patients started on warfarin must be started on an additional
anticoagulant (e.g. heparin) at the same time because warfarin temporarily causes a prothrombotic state. Low molecular
weight heparin is not recommended in end-stage renal disease.

338. Head And Neck Cancers Nontender, solitary cervical lymph nodes are concerning for mucosal head and
neck squamous cell carcinoma, especially in an adult patient with a smoking history.

339. Vitamin K Deficiency Vitamin K deficiency is usually due to inadequate dietary intake, intestinal
malabsorption, or hepatocellular disease. An acutely ill patient with underlying liver disease can become vitamin K
deficient in 7-10 days. Laboratory studies usually show prolonged prothrombin time followed by prolonged partial
thromboplastin time.

340. Spinal Cord Compression Epidural spinal cord compression must be suspected in any patient with
a history of malignancy who develops back pain with motor and sensory abnormalities. Bowel and bladder dysfunction
are late neurologic findings. Intravenous glucocorticoids should be given without delay. MRI is then recommended.

341. Venous Thromboembolism Inferior vena cava filters are placed to prevent clinically significant
pulmonary emboli in patients with contraindications to or complications from anticoagulation (e.g. active bleeding) and
those who have recurrent proximal deep venous thrombosis who failed anticoagulation.

342. Head And Neck Cancers Squamous cell carcinoma in a cervical lymph node, especially in a smoker, likely
has a mucosal head and neck primary site and requires examination of the laryngopharyngeal mucosa.

343. Extragonadal Germ Cell Tumor The differential diagnosis for an anterior mediastinal mass includes the
‘4 T's': thymoma, teratoma (and other germ cell tumors), thyroid neoplasm, and terrible lymphoma. Seminomas may
cause an elevated β-hCG, but the AFP is essentially always normal. Nonseminomatous germ cell tumors often have an
elevated AFP, with a considerable number also having an elevated β-hCG.

344. Heparin Induced Thrombocytopenia Suspected heparin-induced thrombocytopenia requires

immediate cessation of all forms of heparin and initiation of anticoagulation with an alternate agent (e.g. argatroban,
fondaparinux). Once the platelet count is > 150,000/mm3, most patients can be switched safely to warfarin.

345. Sepsis Patients with suspected sepsis require early aggressive fluid resuscitation and broad-spectrum
antibiotic therapy. Patients should receive rapid infusion of large volumes (e.g. 30 mL/kg) of crystalloid fluid within the
first 3 hours and broad-spectrum empiric antibiotics within 1 hour.

346. Thermal Burn When invasive infection is suspected in patients with severe burn injuries, empiric
antibiotic therapy is required, typically with coverage against both gram-positive skin flora (including methicillin-resistant
Staphylococcus aureus) and gram-negative organisms (including Pseudomonas aeruginosa). Piperacillin-tazobactam or a
carbapenem, in combination with vancomycin, are common first-line therapy.

347. Thermal Burn Patients with severe burn injuries are at high risk for sepsis. Acute enteral feeding
intolerance may be an early sign of sepsis, indicating end-organ hypoperfusion and dysfunction.
348. Thermal Burn In patients with severe burn injuries, early excision of necrotic tissue and wound closure
(e.g. skin grafting) reduces the risk of burn wound infections.

349. Splenectomy Patients who undergo splenectomy are at high risk for fulminant sepsis with
encapsulated organisms. They should be prescribed amoxicillin-clavulanate to take immediately in the setting of fever
and then should be advised to proceed directly to the nearest emergency department.

350. Skin And Soft Tissue Infections Occlusion of an anal crypt gland can lead to the formation of an
anorectal abscess. Primary treatment is prompt incision and drainage. Systemic antibiotic therapy, which may decrease
recurrence and anorectal fistula formation, should be given to patients with high-risk features (e.g. systemic illness,
diabetes) and considered for all patients.

351. Animal And Human Bite Injuries Puncture of the thin soft tissue overlying the hand metacarpophalangeal
joints (e.g. clenched-fist punch to the human mouth) can result in septic arthritis, presenting with joint pain, erythema,
swelling, fluctuance, and painful range of motion. Treatment requires urgent surgical irrigation and debridement and
antibiotic therapy.

352. Catheter Related Bloodstream Infection Catheter-related bloodstream infections occur approximately
once per year in patients with tunneled hemodialysis catheters. Most cases present with systemic signs of infection (e.g.
fever, malaise, chills) without localizing symptoms. The catheter site frequently appears normal. Initial therapy usually
includes antibiotics, fluid resuscitation, and removal of the dialysis catheter.

353. Skin And Soft Tissue Infections Pseudomonas folliculitis is a self-limited cutaneous eruption that
develops within hours or a few days following exposure to inadequately chlorinated pools or hot tubs. Patients generally
have tender papules, pustules, or nodules and low-grade fever. No treatment is usually necessary, but swimming in the
contaminated water should be avoided.

354. Liver Abscess Pyogenic liver abscesses typically present with fever, right upper quadrant pain,
hepatomegaly, leukocytosis, and elevated liver enzymes; an associated right-sided pleural effusion may occur. Diagnosis
requires abdominal imaging, and management includes blood cultures, antibiotics, and drainage.

355. Community Acquired Pneumonia Fluoroquinolones (e.g. levofloxacin) increase collagen

degradation and are associated with adverse effects, including Achilles tendon rupture, retinal detachment, and aortic
aneurysm rupture. When possible, fluoroquinolone use should be avoided in patients with a known aortic aneurysm or
substantial risk factors for aortic aneurysm.

356. Surgical Wound Infection Smoking is associated with an increased risk of surgical site infection and
poor wound healing. Current smoking is associated with greater risk than past smoking, but patients who quit are still at
increased risk. Smoking cessation is recommended prior to elective surgery, especially if cessation can be achieved at
least 4-6 weeks before surgery.

357. Postoperative Fever Postoperative fever is generally mediated by cytokine release in response to
tissue trauma, blood cell lysis, or infection. Immediate postsurgical fever occurs within hours of the operation and is
usually due to tissue trauma, mismatched blood products, or drug reactions. Acute (1-7 days postoperatively) and
subacute (7-28 days postoperatively) fever is generally driven by infections.

358. Lymphangitis Acute infectious lymphangitis is marked by the formation of proximal, tender,
erythematous streaks at the site of skin wound with regional lymphadenopathy and systemic symptoms (e.g. fever).
Most cases are caused by Streptococcus pyogenes or methicillin-sensitive Staphylococcus aureus; therefore, treatment
with cephalexin is generally curative.

359. Cytomegalovirus Patients who undergo renal transplantations are at risk for cytomegalovirus
reactivation with viremia and/or end-organ disease. Gastrointestinal manifestations are common and include abdominal
 pain, vomiting, bloody diarrhea, and endoscopic evidence of multiple, large, shallow ulcers. Biopsy is the gold standard
for diagnosis of tissue-invasive disease.

360. Vibrio Vulnificus Vibrio vulnificus is a free-living marine bacterium that causes food-borne illness
(through oysters) and wound infections. Wound infections may be mild, but some patients develop rapid-onset, severe,
necrotizing fasciitis with hemorrhagic bullous lesions and septic shock. Patients with liver disease such as cirrhosis, viral
hepatitis, and hereditary hemochromatosis are at particularly high risk.

361. Catheter Related Bloodstream Infection Candidemia is common in patients hospitalized in the intensive
care unit with intravascular catheters. Manifestations include fever, sepsis, and/or multiorgan failure. Blood cultures or
biopsy are usually required for diagnosis. A positive blood culture for Candida should never be considered a
contaminant.
362. Thrombophlebitis Lemierre syndrome (LS) is caused by an oropharyngeal infection, usually
pharyngitis or tonsillitis, that leads to local invasion of the lateral pharyngeal wall and infection of the neurovascular
bundle, especially the internal jugular vein. Thrombosis of this vein allows dissemination of septic emboli to distal sites.
Fusobacterium necrophorum is the most frequent bacterial cause of LS.

363. Septic Arthritis Prosthetic joint infections can be acquired by perioperative contamination or by
extension from an overlying wound infection. Infections due to virulent organisms (e.g. Staphylococcus aureus) present
within the first 3 months with acute pain, fever, and local signs of infection. Infections due to less virulent organisms (e.g.
coagulase-negative staphylococci) have a delayed onset and present with chronic pain, implant loosening, gait
impairment, or sinus tract formation.

364. Osteomyelitis Bacterial infection of a chronic diabetic foot ulcer may be minimally symptomatic and
requires specific assessment. When the bone can be palpated with a probe, the risk of underlying osteomyelitis is greatly
increased. Biopsy and culture of affected bone is critical to confirming the diagnosis and guiding management.

365. Endocarditis Splenic abscess usually presents with the classic triad of fever, leukocytosis, and left
upper quadrant abdominal pain. Patients can also develop left-sided pleuritic chest pain, left pleural effusion, and
splenomegaly. Risk factors for splenic abscess include hematogenous spread, immunosuppression, intravenous drug use,
trauma, and hemoglobinopathies. Infective endocarditis is most commonly associated with splenic abscess.

366. Postoperative Fever Febrile nonhemolytic transfusion reactions occur within 1-6 hours of transfusion
initiation and can present in the immediate (within a few hours) postoperative period in patients who receive blood
products intraoperatively. Other causes of immediate postoperative fever include prior infection or trauma,
inflammation due to surgery, malignant hyperthermia, and anesthetic medications.

367. Animal And Human Bite Injuries Cat bites are at high risk of infection due to inoculation of bacteria into
deep puncture wounds. Amoxicillin with clavulanate has activity against Pasteurella multocida and oral anaerobes and is
the first-line agent for antibiotic prophylaxis.

368. Osteomyelitis Patients with plantar puncture wounds through footwear are at risk for Pseudomonas
aeruginosa osteomyelitis.

369. Osteomyelitis Diabetic foot infections are common in patients with poor glycemic control, neuropathy,
and peripheral vascular disease. Most deep, long-standing diabetic wounds are polymicrobial with a mixture of gram-
positive, gram-negative, and anaerobic organisms. Underlying osteomyelitis is common due to contiguous spread from
the wound.
370. Urinary Tract Infection Clean intermittent catheterization is an effective measure for reducing the risk of
catheter-associated urinary tract infection in patients with neurogenic bladder.

371. Necrotizing Soft Tissue Infections Necrotizing surgical infection is characterized by intense pain in
the wound, decreased sensitivity at the edges of the wound, cloudy-gray discharge, and sometimes crepitus. Early
 surgical exploration is essential.

372. Acute Diarrhea Risk factors for Clostridioides (formerly Clostridium) difficile include recent
hospitalization, advanced age, and recent antibiotic use. Manifestations can range from mild colitis (i.e. watery diarrhea,
low-grade fever, abdominal pain, leukocytosis) to fulminant colitis with toxic megacolon. Diagnosis is confirmed with
stool studies for C. difficile toxin and glutamate dehydrogenase antigen and/or stool assay for C. difficile exotoxin genes.

373. Healthcare Associated Pneumonia Ventilator-associated pneumonia occurs > 48 hours after
intubation and usually presents with fever, purulent secretions, and abnormal chest x-ray. Patients should have lower
respiratory tract sampling (Gram stain and culture) and receive empiric antibiotics.

374. Echinococcosis Echinococcus granulosus is a dog tapeworm endemic to rural, developing countries.
Humans are incidental hosts and usually acquire the infection through the consumption of food or water contaminated
with dog feces. Tapeworm eggs hatch in the small intestine and spread to the viscera (e.g. liver, lung), causing hydatid
cysts. Symptoms are initially rare, but hepatic cysts may grow over time, resulting in right upper quadrant pain, nausea,
vomiting, and hepatomegaly. Imaging typically reveals a large, smooth cyst, often with internal septations.

375. Toxic Shock Syndrome Toxic shock syndrome due to Staphylococcus aureus is associated with
menstruation (tampons), nasal packing, and post-surgery infections. Patients usually develop fever, myalgias, marked
hypotension, and diffuse erythematous macular rash (erythroderma) that can progress to multiorgan involvement.

376. Ludwig Angina Ludwig angina is a rapidly progressive cellulitis of the submandibular and sublingual
spaces. The source of infection is most commonly an infected mandibular molar. Early intervention with intravenous
antibiotics prevents airway compromise in most cases.

377. Postoperative Fever Coagulase-negative staphylococci are the most frequent cause of nosocomial
bloodstream infection in patients with intravascular devices. Factors favoring infection over contamination include fever,
leukocytosis, hypotension, and blood culture growth in > 2 bottles (both aerobic and anaerobic) with the same organism
and drug susceptibility.

378. Animal And Human Bite Injuries Human bite wounds often result in polymicrobial infections with aerobic
and anaerobic oral organisms. Empiric treatment with amoxicillin-clavulanate provides adequate coverage for the
majority of virulent oral bacteria.

379. Echinococcosis In humans, hepatic hydatid cysts are due to infection with Echinococcus granulosus.
Dogs are the definitive host. A cystic hepatic lesion with eggshell calcification is highly suggestive of infection with this
organism.
380. Liver Abscess Entamoeba histolytica is a protozoan that can cause colitis or extraintestinal (liver,
pleura, brain) illness in patients who live in or travel to developing countries. Amebic liver abscess is characterized by
right upper quadrant pain, fever, and (usually) a single subcapsular lesion in the right lobe. Diagnosis is made with
serology; needle aspiration is usually unnecessary.

381. Necrotizing Soft Tissue Infections Necrotizing fasciitis presents with erythema and swelling, severe
pain out of proportion to the physical examination, and signs of tissue necrosis such as crepitus, purulent drainage, or
radiographic evidence of gas in the deep tissues. When skin or soft-tissue infection is suspected, rapid progression of
physical examination findings or severe systemic signs such as hypotension should raise suspicion for necrotizing fasciitis.

382. Benign Prostatic Hyperplasia Transurethral resection of the prostate is an effective treatment for
benign prostatic hyperplasia. However, this procedure does not preclude the prostate tissue from growing back and
causing bladder outlet obstruction. Other common complications of this procedure are urinary incontinence and urethral
stricture.
383. Priapism Most cases of priapism are idiopathic. However, it can be seen in hematologic disorders
that cause altered blood viscosity or local microthrombi, leading to decreased outflow through the emissary veins.
 Common disorders include sickle cell disease, hematologic malignancies (e.g. chronic myelogenous leukemia),
thalassemia, and multiple myeloma.

384. Priapism Priapism is a persistent, painful erection in the absence of ongoing sexual stimulation.
Sickle cell disease is associated with an increased risk of priapism due to altered blood viscosity and resulting venous
obstruction. Initial management of priapism includes aspiration of blood from the corpora cavernosa, often followed by
intracavernous injection of phenylephrine.

385. Male Circumcision Neonatal circumcision is an elective procedure associated with several medical
benefits, including reduced risk of urinary tract infections in the first year of life and penile phimosis, cancer, and
inflammatory disorders in adulthood. Circumcision also decreases the risk of acquiring some, but not all, sexually
transmitted infections.

386. Penile Injury After initial stabilization, burn patients who require aggressive fluid resuscitation (e.g.
due to burns covering a large total body surface area) should undergo urethral catheterization as soon as possible.

387. Peyronie Disease Peyronie disease is an acquired disorder characterized by fibrosis of the tunica
albuginea of the penis, which restricts tissue expansion and flexibility during erections. Manifestations often include
penile pain, curvature, and/or dorsal nodules/plaques; distortion of the normal erectile shape of the penis may make
sexual intercourse difficult.

388. Prostate Cancer The greatest risk factor for prostate cancer is advanced age; approximately 30%-80% of
men age > 70 have histologic evidence of prostate cancer. Less-prominent risk factors include black ethnicity and a diet
high in meat and low in fruits and vegetables.

389. Varicocele Varicoceles typically present as a clustered scrotal mass above the testis. Men with a
varicocele can have reduced fertility, possibly due to increased scrotal temperatures that can cause a reduced sperm
count and decreased motility.

390. Cryptorchidism Unilateral cryptorchidism can be monitored until age 6 months, after which spontaneous
descent is unlikely. In such a case, orchiopexy is indicated before age 1 to reduce the risk of testicular torsion, infertility,
and testicular malignancy.

391. Benign Prostatic Hyperplasia Benign prostatic hyperplasia can gradually compress the prostatic
urethra, leading to incomplete bladder emptying and an increased risk for recurrent urinary tract infections.

392. Prostatitis Chronic bacterial prostatitis often presents with symptoms of recurrent urinary tract
infection, painful ejaculation, and/or prostatic tenderness in young or middle-aged men. Patients often have transient
improvement of symptoms with short courses of antibiotics. Six weeks of a fluoroquinolone is generally required for
eradication.
393. Prostatitis Acute bacterial prostatitis is characterized by fever, dysuria, and a swollen, tender
prostate. Most cases are caused by coliform organisms (e.g. Escherichia coli) that have contaminated the urethra and
entered the prostate via intraprostatic urinary reflux. Urine culture is required to define the underlying pathogen, but 6
weeks of therapy with trimethoprim-sulfamethoxazole or a fluoroquinolone is generally required to ensure eradication.

394. Prostatitis Chronic bacterial prostatitis generally causes recurrent urinary tract infection symptoms
and prostatic swelling and tenderness. Most cases arise when coliform pathogens enter the prostate from the urethra;
Escherichia coli is the leading pathogen.

395. Varicocele A varicocele is a tortuous dilation of the pampiniform plexus surrounding the spermatic
cord and testis. It presents as a soft, irregular mass that increases in size with standing and Valsalva. The diagnosis is
confirmed with ultrasound. Initial interventions include scrotal support and simple analgesics. Varicoceles are associated
with increased risk for infertility; for patients with testicular atrophy or changes in semen analysis, surgical venous
 ligation can improve fertility.

396. Necrotizing Soft Tissue Infections Fournier gangrene is a life-threatening necrotizing fasciitis that
typically affects perineal, scrotal, and lower abdominal skin. Patients generally have rapid-onset swelling, tenderness,
and crepitus of the affected region and significant systemic symptoms (e.g. hypotension, high fever). Rapid surgical
intervention is required to prevent death and should not be delayed for imaging.

397. Epididymitis Acute epididymitis is associated with posterior testicular pain/swelling, improvement of
pain with testicular elevation, and normal cremasteric reflex. Most cases are caused by sexually transmitted pathogens
(e.g. Chlamydia, Neisseria) in patients age < 35 and by colonic pathogens (e.g. Escherichia coli) in those age > 35.
Treatment with antibiotics is required.

398. Testicular Torsion Testicular torsion can present with acute testicular pain and swelling after mild
trauma. The diagnosis may be made clinically; however, in patients in whom the diagnosis is unclear, a Doppler
ultrasound of the scrotum can confirm the diagnosis and exclude other etiologies.

399. Testicular Torsion Testicular torsion is caused by twisting of the spermatic cord and may result in
testicular necrosis and nonviability. Patients have severe scrotal pain and swelling and may report prior episodes that
resolved without intervention. A reactive hydrocele may be visible on ultrasound; heterogeneous echotexture indicates
testicular necrosis.

400. Testicular Torsion Testicular torsion presents with abrupt onset of scrotal, inguinal, or abdominal
pain, which classically does not resolve with elevation of the testicle. Torsion can occur after exercise, and patients may
have recurring, transient symptoms due to intermittent torsion.

401. Testicular Cancer Testicular germ cell tumors are common in young men and manifest primarily
with a painless testicular mass. However, a minority of patients may have symptoms of metastatic disease, including low
back pain (retroperitoneal lymphadenopathy) and dyspnea/cough (pulmonary nodules). Testicular examination showing
a firm, ovoid testicular nodule should prompt a scrotal ultrasound and tumor markers to support the diagnosis.

402. Benign Prostatic Hyperplasia Cystoscopy is recommended for patients with gross hematuria or with
microscopic hematuria and other risk factors for bladder cancer. Risk factors for bladder cancer include cigarette
smoking, certain occupational exposures (e.g. painters, metal workers), chronic cystitis, iatrogenic causes (e.g.
cyclophosphamide), and pelvic radiation exposure.

403. Varicocele A varicocele is a dilation of the pampiniform plexus that presents as an irregular scrotal
mass that increases in size with Valsalva maneuvers and does not transilluminate.

404. Testicular Cancer Leydig cell testicular tumors often cause feminization (e.g. gynecomastia) due to
the production of estrogen by tumor cells. This frequently causes secondary inhibition of FSH and LH. Serum tumor
markers (e.g. β-hCG, AFP) are not usually elevated.

405. Penile Injury Penile fracture is most commonly caused by blunt trauma (e.g. sexual intercourse) to an
erect penis. Although penile fracture is a urologic emergency that requires urgent operative repair, patients with
evidence of urethral injury (e.g. blood at the meatus, dysuria, urinary retention) should undergo retrograde
urethrography prior to surgery.

406. Testicular Cancer A solid, firm, nontender testicular mass should be considered testicular cancer
until proven otherwise. A diagnostic workup generally includes bilateral scrotal ultrasound, serum tumor markers, and
radical inguinal orchiectomy.

407. Blunt Abdominal Trauma Patients with blunt abdominal trauma and suspected intra-abdominal
hemorrhage (e.g. free intraperitoneal fluid) on Focused Assessment with Sonography for Trauma examination are
 managed according to their hemodynamic status. Hemodynamically stable patients can tolerate further imaging and
should undergo contrast CT scan of the abdomen and pelvis.

408. Incisional Hernia Incisional hernias develop due to fascial closure breakdown and may have a
delayed presentation (months-years). Patients typically have a slowly enlarging abdominal mass (i.e. protruding
abdominal contents) that is palpable while supine and enlarges with the Valsalva maneuver.

409. Shoulder Dislocation Violent muscle contractions (e.g. seizure, electrocution injury) can cause
posterior shoulder dislocation. On examination, the arm is held in adduction and internal rotation, with flattening of the
anterior aspect of the shoulder. X-rays show loss of the normal relation between the humeral head and glenoid and
internal rotation of the humeral head. Most posterior dislocations are managed with closed reduction.

410. Brain Herniation Subfalcine herniation, a type of brain herniation, occurs when the cingulate
gyrus is displaced under the falx cerebri. This typically does not cause pupillary involvement but may cause ipsilateral
anterior cerebral artery compression that leads to contralateral leg weakness.

411. Hemorrhagic Stroke Cocaine use can precipitate intracranial hemorrhage and should be suspected
when stroke occurs in a subcortical location and/or in young patients with associated sympathetic activation or an
absence of typical risk factors.

412. Cervical Myelopathy Cervical myelopathy often causes both spinal cord and spinal nerve root
compression, resulting in myelopathic symptoms (e.g. upper motor neuron signs below the lesion) and radicular
symptoms (e.g. lower motor neuron signs, pain in a dermatomal/myotomal pattern). Lhermitte sign (electric shock-like
pain with neck flexion) may occur.

413. Radiculopathy Cervical radiculopathies occur due to spinal nerve root compression and typically causes
neck pain associated upper extremity sensorimotor deficits that follow a dermatomal/myotomal pattern. Lateral flexion
and rotation of the neck worsens compression of the nerve root, worsening pain and/or paresthesia.

414. Radiculopathy Cervical radiculopathy is due to nerve root compression and typically presents with neck
or arm pain associated with sensorimotor deficits; radiation of pain with neck movement may occur. The diagnosis is
usually made clinically, and most patients improve with symptomatic treatment, including nonsteroidal anti-
inflammatory drugs and avoidance of triggering activities.

415. Hemorrhagic Stroke Management of hemorrhagic stroke focuses on preventing further bleeding (e.g.
blood pressure control, anticoagulant reversal) and maintaining normal intracranial pressure. Hypertension is treated
with a reversible and titratable antihypertensive (e.g. intravenous nicardipine).

416. Spinal Cord Injury Whiplash most commonly causes cervical strain without associated cervical
spine fracture. Patients with cervical trauma should be evaluated using validated clinical decision rules (e.g. National
Emergency X-Radiography Utilization Study [NEXUS] low-risk criteria) to determine whether cervical spine imaging is
needed.
417. Traumatic Brain Injury Traumatic brain injury can cause damage to cortical areas responsible for
inhibiting lower sympathetic centers. This disrupted inhibition may result in paroxysmal sympathetic hyperactivity, a
syndrome characterized by rapid-onset episodes of tachycardia, hypertension, and tachypnea often accompanied by
fever and diaphoresis.

418. Traumatic Brain Injury Osmotic therapy (e.g. hypertonic saline, mannitol) is part of the initial treatment
of elevated intracranial pressure in patients with traumatic brain injury. It creates an osmolar gradient that draws water
out of the edematous brain tissue, thereby reducing parenchymal volume and overall intracranial pressure.

419. Traumatic Brain Injury Acute traumatic coagulopathy, a state of hypocoagulability and hyperfibrinolysis,
can complicate traumatic brain injury (TBI). Antifibrinolytic therapy (i.e. tranexamic acid) can improve outcomes for
 patients with moderate TBI if administered within the first 3 hours after injury.

420. Spinal Cord Injury The presence of a single vertebral fracture in a patient with blunt trauma is an
indication to image the entire spine. CT scan is the screening modality of choice because of its sensitivity and accuracy.

421. Spinal Cord Injury CT scan is the preferred test to screen for cervical spine injury. Indications
include high-energy mechanism of injury or any of the following findings: neurologic deficit, spinal tenderness, altered
mental status, intoxication, or distracting injury.

422. Subarachnoid Hemorrhage Subarachnoid hemorrhage typically presents with a sudden-onset,

severe headache that may be accompanied by vomiting, neck stiffness, fever, and loss of consciousness. CT scan of the
brain is the best initial diagnostic step.

423. Spinal Cord Injury Cervical facet dislocation typically occurs with forced flexion of the cervical spine
(e.g. falling onto a flexed neck); a single facet is usually dislocated and results in radiculopathy of the corresponding
nerve root. The most commonly affected vertebral bodies are C5/C6, which lead to C6 radiculopathy, and C6/C7, which
lead to C7 radiculopathy. Imaging demonstrates anterior subluxation of the vertebral bodies.

424. Spinal Cord Injury CT scan is the preferred test to screen for cervical spine injury. Indications
include high-energy mechanism of injury or any of the following findings: neurologic deficit, spinal tenderness, altered
mental status, intoxication, or distracting injury.

425. Pituitary Apoplexy Pituitary apoplexy involves sudden hemorrhage into an enlarged pituitary
adenoma. Patients typically have sudden onset of severe headache and visual disturbances. There is also loss of pituitary
function; because cortisol helps maintain vascular tone, the absence of ACTH-induced cortisol production can lead to
adrenal crisis (acute adrenal insufficiency) with severe hypotension and distributive shock.

426. Copper Deficiency Copper deficiency typically occurs in patients with a history of gastric surgery
(e.g. bariatric), chronic malabsorption (e.g. inflammatory bowel disease), or excessive zinc ingestion. Symptoms include
slowly progressive myeloneuropathy similar to that of vitamin B12 deficiency (e.g. distal extremity paresthesia,
numbness, sensory ataxia), anemia, hair fragility, skin depigmentation, hepatosplenomegaly, edema, and osteoporosis.

427. Orbital Fracture An orbital floor fracture can result in entrapment of the inferior rectus muscle, which
presents with vertical diplopia and restriction of upward eye movement.

428. Neurofibromatosis Vestibular schwannomas present with hearing loss and imbalance. Bilateral,
hereditary schwannomas are most often associated with neurofibromatosis type ll.

429. Carpal Tunnel Syndrome Carpal tunnel syndrome is the most common mononeuropathy in
patients with end-stage renal disease on dialysis. It is characterized by pain and paresthesia in the lateral hand;
symptoms typically worsen during dialysis and are more severe in the arm with vascular access.

430. Carpal Tunnel Syndrome Carpal tunnel syndrome is common in patients with hypothyroidism and
is frequently bilateral. Hypothyroidism causes soft tissue thickening and mucinous infiltration, which can lead to
compression of the median nerve within the carpal tunnel.

431. Epidural Hematoma Spinal epidural hematoma is a potential complication of neuraxial anesthesia
(e.g. epidural block), lumbar puncture, or spinal surgery and is more common in older adults taking antithrombotic
medications. Manifestations include slowly progressive motor and sensory dysfunction and localized back pain; bowel
and bladder dysfunction may occur. Management includes an urgent MRI and neurosurgical decompression.

432. Epidural Hematoma Epidural hematomas occur due to tearing of the middle meningeal artery and
typically occur with skull fracture. Although patients classically present with loss of consciousness followed by a lucid
 interval, many initially remain alert. However, hematoma expansion results in neurologic decompensation with signs of
elevated intracranial pressure (e.g. headache, nausea/vomiting, altered mental status) within minutes to hours.

433. Hemorrhagic Stroke Cerebellar hemorrhage presents with progressive headache, nausea, and
vomiting; in addition, vertigo, ipsilateral truncal (cerebellar vermis) or limb (cerebellar hemispheres) ataxia, dysarthria,
and nystagmus may occur. CT scan demonstrates a posterior fossa hyperdensity. Urgent surgical decompression is
indicated in patients with signs of neurologic deterioration or radiologic evidence of a hemorrhage > 3 cm, brainstem
compression, or obstructive hydrocephalus.

434. Rheumatoid Arthritis Patients with rheumatoid arthritis are at risk for atlantoaxial instability; neck
extension during intubation can result in subluxation with cord compression and cervical myelopathy. Symptoms of
cervical myelopathy include a slowly progressive, spastic paraparesis involving the upper and lower extremities,
hyperreflexia, sensory changes, and a positive Babinski sign. Hoffman sign may also be positive.

435. Spinal Cord Injury Acute spinal cord injury often manifests with loss of spinal cord function (e.g.
areflexia, anesthesia, paralysis, distended bladder) below the level of the lesion. Lesions that arise above T1 also often
cause neurogenic shock due to interruption of the descending sympathetic fibers, which results in unopposed
parasympathetic stimulation of the vessels (hypotension) and heart (bradycardia). Hypothermia is also common due to a
lack of peripheral vasoconstriction.

436. Spinal Cord Injury Central cord syndrome is common after whiplash-type injuries in older adults
with underlying cervical spondylosis. Damage to the central cervical spinal cord causes upper extremity motor, sensory,
and reflex abnormalities; sacral (e.g. bowel/bladder) and lower extremity function is generally preserved.

437. Spinal Cord Injury Spinal cord injury above T6 can be complicated by autonomic dysreflexia, in
which noxious stimuli below the injury level trigger an unregulated sympathetic response, leading to severe
hypertension. A compensatory parasympathetic response above the lesion typically causes bradycardia. Management
includes removing noxious stimuli and treating the hypertension.

438. Normal Pressure Hydrocephalus Normal pressure hydrocephalus (NPH) is characterized by

ventriculomegaly with normal opening pressure on lumbar puncture. It classically presents with a triad of incontinence,
cognitive impairment, and gait abnormalities; however, all symptoms may not be present in early disease. NPH can be
idiopathic or occur secondary to neurologic insults (e.g. subarachnoid hemorrhage, trauma, meningitis) that result in
scarring of the arachnoid granulations responsible for cerebrospinal fluid resorption.

439. Malignant Hyperthermia Malignant hyperthermia is a genetic disorder associated with sudden-
onset tachypnea, tachycardia, myoglobinuria, and masseter/generalized muscle rigidity following exposure to
succinylcholine or a volatile anesthetic. Most cases arise during or shortly after induction, but symptoms are sometimes
delayed until just after anesthesia cessation.

440. Hemorrhagic Stroke Intracerebral hemorrhage (ICH) typically presents with progressive headache,
nausea/vomiting, and altered mental status over a period of minutes to hours. ICH in young patients is commonly due to
arteriovenous malformation, which may also present with recurrent headache, seizure, or focal neurologic deficits.

441. Botulism Wound botulism occurs when Clostridium botulinum spores contaminate a puncture
injury (e.g. intravenous needle), germinate, and generate neurotoxin in vivo. Manifestations include symmetric,
descending neurologic deficits (e.g. cranial nerve palsy), respiratory compromise, and autonomic dysfunction. In contrast
to foodborne and infant botulism, fever and leukocytosis may be present. Urgent treatment with equine botulinum
antitoxin is required and should not be delayed for diagnostic evaluation.

442. Cervical Myelopathy The most common cause of cervical myelopathy in older adults is spondylosis, a
degenerative spine disease that causes canal narrowing with spinal cord compression. Manifestations include
progressive gait instability and weakness in the extremities. Examination usually shows lower motor neuron signs at the
 level of the lesion (arms) and upper neuron signs below the level of the lesion (legs).

443. Cauda Equina Syndrome Cauda equina syndrome is most common following a large lumbosacral
disc herniation. Suspicion should be raised in those with severe low back pain radiating into one or both legs with
accompanying saddle anesthesia (sensory change in the genitals/perineum) and/or bladder, bowel, or sexual
dysfunction. An urgent lumbosacral spine MRI is required for diagnosis, followed by surgical decompression.

444. Brain Tumors The presence of an extra-axial well-circumscribed dural-based mass that is partially
calcified on neuroimaging is strongly suggestive of a meningioma. Meningiomas are considered benign primary brain
tumors; however, they can present with headache, seizure, and focal neurologic deficits due to mass effect. In such
cases, complete surgical resection is recommended.

445. Syringomyelia Syringomyelia is characterized by a fluid-filled cavity (syrinx) in the spinal cord that
compresses the surrounding tissue. It is most commonly seen in patients with Arnold-Chiari type 1 malformations or
spinal cord injury. It typically affects the crossing fibers of the spinothalamic tract in the ventral white commissure (loss
of pain and temperature sensation with preserved touch, vibration, and proprioception) and may affect motor fibers in
the ventral horns (flaccid paralysis). The diagnosis is confirmed by MRI, and management usually requires surgical
intervention.
446. Normal Pressure Hydrocephalus Normal pressure hydrocephalus is characterized by abnormal gait,
urinary incontinence, and cognitive impairment; however, only gait dysfunction is required for diagnosis. Neuroimaging
demonstrates ventriculomegaly out of proportion to cerebral atrophy. The diagnosis is confirmed with high-volume
lumbar puncture demonstrating improvement of gait with cerebrospinal fluid removal. Definitive treatment is ventricular
shunt placement.

447. Shoulder Dislocation Acute shoulder pain after forceful abduction and external rotation at the
glenohumeral joint suggests an anterior shoulder dislocation, which may cause injury to the axillary nerve. The axillary
nerve innervates the teres minor and the deltoid, and injury can result in weakened shoulder abduction and decreased
sensation over the lateral shoulder.

448. Brain Herniation Rapid hematoma (e.g. epidural) expansion after head injury can abruptly
increase intracranial pressure, compress the temporal lobe, and cause uncal herniation. The first sign is typically an
ipsilateral fixed and dilated pupil due to oculomotor nerve (CN III) compression. Contralateral hemiparesis is often seen
due to direct compression of the ipsilateral cerebral peduncle.

449. Femoral Neuropathy The femoral nerve is responsible for knee extension and hip flexion and provides
sensation to the anterior thigh and medial leg. It is vulnerable to injury from pelvic fracture, hip dislocation, or iliacus
hematoma and can suffer iatrogenic injury during prolonged maintenance of the dorsal lithotomy position (e.g.
hip/pelvic surgery, childbirth) or vascular procedures involving the femoral artery or vein.

450. Anterior Cord Syndrome Thoracic aortic aneurysm repair can cause spinal cord ischemia,
especially of the anterior cord. Anterior cord syndrome typically presents with distal, bilateral flaccid paralysis; loss of
pain/temperature and crude touch sensation; and urinary retention.

451. Subdural Hematoma Subdural hematoma results from the rupture of bridging veins, most commonly
from head trauma. Risk factors include advanced age and chronic alcoholism (due to brain atrophy), as well as
anticoagulant use. On noncontrast head CT scan, acute subdural hematoma appears as a crescent-shaped hyperdensity
that crosses suture lines.

452. Epidural Abscess Spinal epidural abscess often presents with several days/weeks of fever, malaise,
and the following progressive neurologic symptoms: focal back pain nerve root pain motor weakness, sensory changes,
and bowel/bladder dysregulation —9 paralysis. Suspected cases require urgent MRI spine; treatment generally includes
surgical decompression and antibiotics. Epidural anesthesia is a common triggering event (due to direct inoculation).
453. Spinal Cord Injury In patients with traumatic spinal cord injury, disruption of the autonomic tracts
involved in bladder control can lead to urinary retention. Therefore, catheterization should be performed to prevent
bladder distension and possible injury.

454. Brain Tumors The typical CT/MRI findings in high-grade (e.g. grade IV) astrocytoma are heterogenous
and serpiginous contrast enhancement. Glioblastoma (grade IV astrocytoma) has a classic butterfly appearance with
central necrosis on neuroimaging.

455. Traumatic Brain Injury Short-term hyperventilation helps lower increased intracranial pressure by
causing cerebral washout of CO2, leading to vasoconstriction and decreased cerebral blood flow.

456. Central Cord Syndrome Hyperextension injury, especially in elderly patients with cervical spine
degenerative changes (i.e. cervical spondylosis), can cause central cord syndrome. This classically causes loss of pain and
temperature sensation in the upper extremities and disproportionate upper extremity weakness.

457. Ocular Trauma A hyphema is a collection of blood in the anterior chamber of the eye that occurs
typically following blunt or penetrating ocular trauma. Management involves preventing complications, such as
rebleeding and intraocular hypertension, which can result in optic nerve injury and permanent vision loss.

458. Cataract Cataracts typically develop in patients age > 60 but may be seen in younger individuals
due to HIV infection, diabetes mellitus, ocular trauma, glucocorticoid use, or external radiation exposure. Treatment for
cataracts includes surgical removal of the lens with implantation of a prosthetic lens.

459. Glaucoma Topical glucocorticoid eyedrops and systemic glucocorticoids can raise intraocular
pressure (IOP), leading to open-angle glaucoma (OAG). OAG is usually characterized by insidious loss of peripheral vision,
and some patients with steroid-induced OAG may develop central blurriness due to corneal edema. IOP can be measured
with tonometry.

460. Ocular Trauma Open globe laceration (OGL) is typically caused by small, high-velocity particles sent
airborne by power tools, explosions, lawn mowers, or motor vehicle accidents. Large OGL may present with globe
deformity, extrusion of vitreous or iris, or a visible entry wound. Other manifestations include a peaked or teardrop
pupil, asymmetric anterior chamber depth, loss of visual acuity or afferent pupillary response, and reduced intraocular
pressure.
461. Hyperthyroidism Graves ophthalmopathy is characterized by ocular irritation, impaired
extraocular motion, and proptosis. It is caused by T cell activation and stimulation of orbital fibroblasts by thyrotropin
(TSH) receptor autoantibodies, leading to expansion of orbital tissues.

462. Ocular Trauma High-velocity injury to the globe can lead to corneal abrasion or open globe laceration
(OGL). Small injuries may not be visible on routine inspection, but further assessment can be obtained with fluorescein
instillation. In OGL, fluorescein may reveal extrusion of fluid through the laceration; in corneal abrasion, fluorescein
stains the corneal defect and appears yellow.

463. Glaucoma Initial management of angle-closure glaucoma is directed at rapidly lowering intraocular
pressure. Combination therapy with multiple topical agents (e.g. timolol, pilocarpine, apraclonidine) is recommended. In
addition, acetazolamide rapidly reduces further production of aqueous humor. Subsequently, laser iridotomy can
facilitate aqueous outflow and provide definitive management.

464. Ocular Trauma Chemical burns to the eye are vision-threatening emergencies. The most important and
urgent step in management is copious irrigation to normalize the pH.

465. Endophthalmitis Postoperative endophthalmitis is the most common form of endophthalmitis. It

usually occurs within 6 weeks of surgery. Patients usually present with pain and decreased visual acuity. Examination
 reveals swollen eyelids and conjunctiva, hypopyon, corneal edema and infection.

466. Cataract A cataract is a vision-impairing opacification of the lens. Patients usually have painless
blurred vision, glare, and often halos around lights. Treatment with lens extraction and artificial lens implantation is
indicated when loss of vision impairs activities of daily living.

467. Insect Bites And Stings Patients with a Loxosceles reclusa (brown recluse) spider bite initially have a
small, red papule that can progress to form a larger necrotic wound (loxoscelism). Most cases will resolve with the
application of cold packs and local wound care.

468. Snake Bite Venomous snake bite should be managed with close observation and frequent
coagulation studies and wound evaluations. Patients with mild envenomation and normal laboratory studies can be
observed for 12-24 hours. Patients with abnormal laboratory results, progressing symptoms, or signs of systemic toxicity
should receive antivenom.

469. Electrical Injury High-voltage electrical injuries frequently cause more severe damage to internal
structures (e.g. muscle) than external structures (e.g. skin). Skeletal muscle necrosis is a frequent complication that can
result in acute compartment syndrome, rhabdomyolysis, and heme pigment-induced acute kidney injury.

470. Thermal Burn Severe burn injury often leads to a hypermetabolic response characterized by a
hyperdynamic circulatory response, causing tachycardia and hypertension; increased gluconeogenesis and insulin
resistance; and increased protein and lipid catabolism, causing elevated basal body temperature.

471. Insect Bites And Stings Brown recluse spider bites can cause a deep necrotic ulcer at the bite site. The
ulcer can progress over days to an eschar.

472. Thermal Burn Circumferential, full-thickness (third degree) burns can result in eschar formation that
restricts venous and lymphatic drainage, leading to acute compartment syndrome.

473. Wound Dehiscence And Evisceration Superficial wound dehiscence, separation of the epidermis
and/or subcutaneous tissue with an intact fascia, is typically managed conservatively with regular dressing changes. In
contrast, deep (fascial) dehiscence involves the fascia and is a surgical emergency.

474. Alcohol Withdrawal Delirium tremens is a late manifestation of alcohol withdrawal that is
characterized by delirium, hyperthermia, hypertension, and tachycardia 48-96 hours after the last drink. Delirium
tremens is associated with a mortality rate of 5% and requires aggressive intensive care unit-level supportive
management in addition to benzodiazepine therapy.

475. Benzodiazepines Benzodiazepine withdrawal may be characterized by agitation, tremors,

perceptual changes, psychosis, elevated vital signs, delirium, and seizures.

476. Alcohol Withdrawal Delirium tremens is a severe manifestation of alcohol withdrawal usually
presenting 48-96 hours after the last drink. It is defined by autonomic excitation, agitation, tremor, and altered
sensorium.
477. Interstitial Lung Disease Idiopathic pulmonary fibrosis is a disorder of epithelial injury that has been
pathologically repaired by fibrotic responses. Antifibrotic drugs inhibit fibroblasts to slow the rate of lung function
decline and are first-line therapy.

478. Parapneumonic Effusion & Empyema Aspiration pneumonia leading to translocation of anaerobic oral
flora into the intrapleural space is likely the most common cause of empyema, commonly presenting insidiously (e.g.
over 2-3 weeks) with weight loss and similar signs and symptoms to uncomplicated pneumonia. Putrid or foul-smelling
pleural fluid is diagnostic of anaerobic empyema.
479. Parapneumonic Effusion & Empyema Complicated parapneumonic effusions involve bacterial invasion
into the pleural space and require drainage in addition to antibiotic therapy. Positive pleural fluid Gram stain or culture is
diagnostic of a complicated effusion and is an indication for chest tube placement.

480. Lung Abscess Lung abscess is typically marked by subacute fever, putrid-smelling sputum, and a
cavitary lung infiltrate with air-fluid level in a dependent portion of the lung. Patients often have history of swallowing
dysfunction or impaired consciousness. Sputum culture should be obtained but is rarely useful; empiric treatment with
ampicillin-sulbactam or a carbapenem is recommended.

481. Carcinoid Tumors Bronchial carcinoid is the most common lung cancer in adolescents and young
adults. It typically presents with proximal airway obstruction, leading to dyspnea, wheezing, and recurrent pneumonia in
the same lobe of the lung. Carcinoid syndrome is much less common than with gastrointestinal carcinoid tumors.

482. Carcinoid Tumors Bronchial carcinoid tumors are the most common lung malignancy in young
patients who do not smoke. They typically arise in the proximal airway and cause airway obstruction (e.g. dyspnea,
wheezing, pneumonia) or hemoptysis. CT scan with contrast usually reveals an avidly enhancing mass with an
endobronchial component.

483. AV Malformation Hereditary hemorrhagic telangiectasia involves arteriovenous malformations

(AVMs) across multiple organ systems. Nasal telangiectasias lead to recurrent epistaxis, and pulmonary AVMs may cause
hemoptysis.
484. Lung Transplantation Acute lung transplant rejection (ALTR) typically occurs within 6 months of
transplant and may present with progressive dyspnea and cough accompanied by low-grade fever, hypoxemia, and chest
x-ray revealing perihilar opacities and interstitial edema. Because pulmonary infection can have a similar clinical
presentation and the treatment for ALTR (i.e. high-dose glucocorticoids) could markedly worsen an infection,
bronchoalveolar lavage and lung biopsy should be performed in the diagnostic workup of ALTR.

485. Lung Transplantation Bronchiolitis obliterans is the major manifestation of chronic lung transplant
rejection and is common in lung transplant recipients > 5 years post-transplant. The diagnosis is usually made based on a
consistent clinical presentation (e.g. gradually progressive dyspnea and nonproductive cough) and pulmonary function
testing showing an obstructive pattern.

486. Cytomegalovirus Cytomegalovirus (CMV) pneumonitis, an acute, febrile, and diffuse pneumonia,
is a common opportunistic infection in the postacute period (> 1 month) after lung transplantation. It is usually due to
reactivation of latent CMV from the donor lung or the recipient leukocytes. Tissue injury caused by CMV pneumonitis
leads to increased risk of graft rejection and decreased survival.

487. Respiratory Acidosis The phrenic nerve can be injured during cardiac surgery. Patients can have
dyspnea on exertion, orthopnea, and paradoxical breathing movement (i.e. abdomen moving inward on inspiration).

488. Obstructive Shock Most cases of obstructive shock result from pre-pulmonary obstruction (e.g. due
to massive pulmonary embolism or tension pneumothorax) with hemodynamic parameters showing high central venous
pressure (CVP), low pulmonary capillary wedge pressure (PCWP), and low cardiac output. Post-pulmonary obstructive
shock (e.g. due to aortic dissection or severe aortic stenosis) leads to the same findings as cardiogenic shock with high
CVP, high PCWP, and low cardiac output.

489. Air Embolism Venous air embolism (VAE) is suggested by sudden-onset respiratory distress following
removal of a central venous catheter. Patients with suspected VAE should immediately be placed in the left lateral
decubitus position to trap air on the lateral right ventricular wall and help prevent right ventricular outflow tract
obstruction and embolization of air into the pulmonary circulation. High-flow oxygen is also important to encourage
absorption of the air embolus.
490. Penetrating Neck Trauma Venous air embolism results from the introduction of a large volume of
air (e.g. > 50 mL) into the venous circulation; it can occur in the setting of trauma, certain surgeries (e.g. neurosurgical),
central venous catheter manipulation, or pulmonary barotrauma. The air can obstruct blood flow in the right ventricular
outflow tract or pulmonary arterioles, leading to hypoxemia, obstructive shock, and cardiac arrest.

491. Pneumothorax Positive-pressure ventilation can rapidly exacerbate tension pneumothorax (TP) and
cause cardiovascular collapse. Therefore, decompression (e.g. needle thoracostomy) should be performed prior to
intubation for patients with TP who also need airway protection - an important exception to the typical order.

492. Pulmonary Embolism Prophylactic anticoagulation does not eliminate the risk of acute pulmonary
embolism (PE), especially in high-risk patient populations (e.g. postoperative cancer resection). CT pulmonary
angiography is the initial diagnostic test of choice in patients with likely pretest probability of acute PE.

493. Blunt Thoracic Trauma Displaced fractures of ribs 9-12 can injure intra-abdominal organs, including the
spleen. Bleeding that irritates the diaphragm may cause referred pain (e.g. to the left shoulder).

494. Pneumonectomy FEV1 and diffusion capacity of the lung for carbon monoxide (DLCO) are the best
predictors of postoperative outcomes following lung resection surgery.

495. Blunt Thoracic Trauma Tracheobronchial injury should be considered in patients with thoracic trauma
and extensive extrapulmonary air (e.g. chest tube with persistent large air leak). Bronchoscopy can confirm the diagnosis
prior to operative repair.

496. Penetrating Thoracic Trauma Penetrating trauma accompanied by shock (e.g. severe hypotension) is
attributed to hemorrhage until proven otherwise. Intrathoracic hemorrhage can cause massive hemothorax (> 1,500 mL),
which requires emergent thoracotomy to prevent exsanguination.

497. Blunt Thoracic Trauma Hypovolemic shock in the setting of blunt chest trauma is concerning for
intrathoracic hemorrhage. Rib fractures (with intercostal vessel injury) are a common cause of hemothorax.

498. Foreign Body Aspiration Foreign body aspiration should be suspected in a child with abrupt-onset cough
and wheeze (with or without a choking episode) that is unresponsive to albuterol. Supportive findings include a focal
lung examination (e.g. wheeze, decreased breath sounds, hyper-resonance) and/or unilateral lung hyperinflation with
mediastinal shift on x-ray.

499. Acute Respiratory Failure Positive-pressure ventilation improves gas exchange but poses the risk
of pulmonary barotrauma, leading to alveolar rupture and subsequent pneumothorax formation. Patients with a large
pneumothorax often demonstrate rapid-onset tachycardia, tachypnea, hypoxemia, and decreased or absent breath
sounds on the affected side.

500. Healthcare Associated Pneumonia Ventilator-associated pneumonia should be suspected when an

intubated patient develops new pulmonary infiltrates on chest x-ray, worsened respiratory status (e.g. increased oxygen
requirement, increased secretions), and clinical signs of infection (e.g. fever, leukocytosis). Confirmation requires the
identification of an organism in a lower respiratory tract sample.

501. Healthcare Associated Pneumonia Ventilator-associated pneumonia is a hospital-acquired

pneumonia that develops > 48 hours after endotracheal intubation. Most cases arise due to aspiration of oropharyngeal
or gastric secretions. Therefore, the risk is reduced by elevating the head of the bed to 30-45 degrees, suctioning
subglottic secretions, limiting endotracheal tube movement, and avoiding gastric acid suppression, unless patients are at
high risk of stress ulcers.
502. Airway Emergency Ludwig angina is a rapidly progressive cellulitis of the submandibular and
sublingual spaces. Airway obstruction can occur due to displacement of the tongue posteriorly.

503. Fat Embolism Fat embolism syndrome can occur following fracture of large, marrow-containing bones
(e.g. femur, pelvis). Patients classically have the triad of respiratory distress, neurologic dysfunction, and a petechial rash;
however, the rash is present in less than half of cases.

504. Transfusion Related Acute Lung Injury Transfusion-related acute lung injury typically occurs within
minutes or a few hours of blood product transfusion. It manifests with acute hypoxemic respiratory failure and bilateral
pulmonary infiltrates. In contrast to patients with transfusion-associated circulatory overload, those with TRALI typically
have normal brain natriuretic peptide and no jugular venous distension.

505. Lung Abscess Lung abscess is common in patients with periods of impaired consciousness (e.g.
alcohol/drug abuse, seizure disorder) or swallowing dysfunction (e.g. Parkinson disease). It usually presents with indolent
systemic symptoms and cough productive of foul-smelling sputum. Chest x-ray usually reveals a cavitary infiltrate in a
dependent portion of the lung.

506. Aspiration Pneumonia Aspiration pneumonitis is an acute lung injury secondary to a chemical burn
from aspirated sterile gastric contents. In contrast, aspiration pneumonia is an infectious disease caused by aspiration of
infected oropharyngeal secretions.

507. Hemoptysis Initial management in hemoptysis involves establishing adequate patent airway,
maintaining adequate ventilation and gas exchange, and ensuring hemodynamic stability. Patients should be placed with
the bleeding lung in the dependent position (lateral position). Bronchoscopy is the procedure of choice to identify the
site and attempt early therapeutic intervention.

508. Hemoptysis Patients with hemoptysis and high clinical suspicion for pulmonary tuberculosis should
be placed in respiratory isolation to prevent the spread of infection before further diagnostic evaluation and treatment.

509. Atelectasis Deep-breathing exercises and incentive spirometry can help prevent postoperative
atelectasis. Adequate postoperative pain control can also help by minimizing pain-induced restriction of chest expansion
during respiration.

510. Atelectasis Postoperative atelectasis is common and typically manifests 2-5 days following surgery.
Hypoxemia results from localized intrapulmonary shunting and ventilation-perfusion mismatch, and hyperventilation
leads to primary respiratory alkalosis with low PaCO2 and high pH.

511. Atelectasis Atelectasis is a common postoperative complication that results from shallow breathing
and weak cough due to pain. It is most common on postoperative days 2 and 3 following abdominal or thoracoabdominal
surgery. Adequate pain control, deep-breathing exercises, directed coughing, early mobilization, and incentive
spirometry decrease the incidence of postoperative atelectasis.

512. Thermal Burn In burn patients, clinical indicators of thermal inhalation injury to the upper airway
and/or smoke inhalation injury to the lungs include burns on the face, singeing of the eyebrows, oropharyngeal
inflammation/blistering, oropharyngeal carbon deposits, carbonaceous sputum, stridor, carboxyhemoglobin level > 10%,
or history of confinement in a burning building. The presence of > 1 of these indicators warrants early intubation to
prevent upper airway obstruction by edema.

513. Parapneumonic Effusion & Empyema Bacterial pneumonia commonly causes a pleural effusion. Often
the effusion is small, sterile, and resolves with antibiotics (uncomplicated). However, if bacteria persistently cross into
the pleural space, a complicated parapneumonic effusion or empyema can develop. Empyemas have frank pus or
bacteria (by Gram stain) in the pleural space and require drainage (chest tube) in addition to prolonged antibiotics.
514. Rib Fracture Fracture of > 3 contiguous ribs in > 2 locations can result in flail chest, with paradoxical
movement of the fractured flail segment during respiration. Flail chest can cause hypoxia due to ineffective ventilation,
pulmonary contusion, and atelectasis.

515. Blunt Thoracic Trauma Flail chest should be suspected in patients with respiratory distress and multiple
rib fractures. Flail chest increases work of breathing and may injure the underlying lung, often leading to respiratory
failure.
516. Hypovolemia Positive-pressure mechanical ventilation causes an acute increase in intrathoracic
pressure. In the setting of decreased central venous pressure (e.g. hypovolemic shock), initiation of mechanical
ventilation can cause acute loss of right ventricular preload, loss of cardiac output, and cardiac arrest.

517. Prevention Of Postoperative Pneumonia Postoperative pulmonary complications are common,

particularly in patients with known risk factors. These risk factors include smoking, pre-existing pulmonary disease, age >
50, thoracic or abdominal surgery, surgery lasting > 3 hours, and poor general health. Postoperative measures such as
incentive spirometry and deep breathing exercises are used to prevent such complications and improve outcomes by
promoting lung expansion.

518. Hypovolemia Hypovolemic shock involves an initial decrease in preload and cardiac output followed by
a compensatory increase in systemic vascular resistance, heart rate, and ejection fraction. Hypotension, tachycardia, cold
extremities, and evidence of hypovolemia (e.g. decreased jugular venous pressure) should be present.

519. Blunt Thoracic Trauma Hypovolemic shock in the setting of blunt trauma is concerning for hemorrhage.
Decreased breath sounds and dullness to percussion, with contralateral tracheal deviation, is most likely due to a
massive hemothorax.

520. Pneumothorax Primary spontaneous pneumothorax (PSP) occurs in patients without a history of lung
disease and is most common in tall, thin men in their early 20s. Management of small PSP in clinically stable patients
includes observation and supplemental oxygen, which enhances the speed of resorption.

521. Pulmonary Contusion Blunt thoracic trauma can injure the underlying lung. The resulting alveolar
hemorrhage and edema - often worsened by fluid resuscitation - can cause dyspnea, tachypnea, and hypoxemia.
Irregular, nonlobular infiltrates on chest x-ray or CT scan are classic for pulmonary contusion.

522. Blunt Thoracic Trauma Rapid deceleration can cause blunt thoracic aortic injury (BTAI). Widened
mediastinum on chest x-ray should increase suspicion for BTAI and left-sided pleural effusion (hemothorax) may be
present from hemorrhage preceding containment (e.g. hematoma). Strict blood pressure control and emergent surgical
intervention are necessary to prevent rebleeding and death.

523. Pneumothorax Secondary spontaneous pneumothorax should be suspected in patients with underlying
lung disease presenting with rapid worsening of respiratory symptoms. Rupture of alveolar blebs is the most common
cause in patients with chronic obstructive lung disease.

524. Lung Nodule Solitary pulmonary nodules < 0.6 cm are unlikely to be malignant, whereas those > 0.8
cm require additional management or surveillance. Nodules that are intermediate or high probability for malignancy (i.e.
> 5% probability) based on clinical factors (e.g. nodule size, patient age, smoking history) should be biopsied or surgically
excised.
525. Blunt Thoracic Trauma Diaphragmatic rupture can have a delayed presentation after blunt
thoracoabdominal trauma due to progressive enlargement of the diaphragmatic defect and herniation of abdominal
organs into the thoracic cavity. Chest x-ray may show elevation of the hemidiaphragm or abdominal organs (e.g.
stomach) in the thorax.
526. Pulmonary Contusion Even without chest wall fracture, blunt thoracic trauma can cause pulmonary
contusion. Tachypnea and hypoxemia are classic symptoms, and imaging often demonstrates patchy, irregular alveolar
infiltrates.
527. Parapneumonic Effusion & Empyema Complicated parapneumonic effusions and empyemas often
present with continued symptoms (fever, pleuritic pain) despite adequate antibiotic coverage for pneumonia. Chest x-ray
usually shows loculation, and thoracentesis reveals fluid that is exudative with low glucose (< 60 mg/dL) and low pH (<
7.2). Most complicated parapneumonic effusions and all empyemas require drainage (e.g. chest tube) in addition to
antibiotics.
528. Bronchogenic Cyst Bronchogenic cysts are usually found in the middle mediastinum. Thymoma is
usually found in the anterior mediastinum. All neurogenic tumors are located in the posterior mediastinum.

529. Lung Abscess Lung abscess is usually due to the aspiration of oropharyngeal anaerobic bacteria.
Patients with dysphagia or episodes of impaired consciousness (e.g. drug or alcohol abuse) are at high risk. Symptoms
include subacute fever, night sweats, weight loss, and cough with putrid sputum. X-ray reveals cavitary infiltrates, often
with air-fluid levels.

530. Pulmonary Embolism The modified Wells criteria can assess the pretest possibility of acute pulmonary
embolism (PE). CT angiography is the test of choice in clinically stable patients in whom PE is likely. Empiric
anticoagulation in these patients is often appropriate, but clinical judgment is needed regarding clinical stability and
contraindications.

531. Extragonadal Germ Cell Tumor Germ cell tumors typically affect young patients and display aggressive
biologic behavior. Nonseminomatous germ cell tumors typically produce both α-fetoprotein and human chorionic
gonadotropin tumor markers.

532. Atelectasis Mucus plugging can lead to large-volume atelectasis (lung collapse) due to airway
obstruction. Chest x-ray demonstrates opacification of the affected lung area and mediastinal shifting toward the side of
atelectasis.
533. Diaphragmatic Hernia Diaphragmatic rupture should be suspected in patients with prior blunt
thoracoabdominal trauma and abnormal chest x-ray findings (e.g. bowel loops in the thorax, mediastinal shift). Delayed
presentations can occur after progressive expansion of the diaphragmatic defect and abdominal organ herniation. CT
scan of the chest and abdomen confirms the diagnosis.

534. Acute Respiratory Failure Delayed emergence from anesthesia is defined as the failure to return to
consciousness within the expected window of the last administration of an anesthetic or adjuvant agent (typically 30-60
minutes). The etiology is often multifactorial, however; the presence of respiratory failure (e.g. low pH, elevated pCO2,
low pO2), bradypnea, and bradycardia suggests prolonged medication effect resulting in hypoventilation.

535. Rib Fracture Adequate pain control is the mainstay of rib fracture management to prevent the
associated complications of atelectasis and pneumonia.

536. Pneumothorax Tension pneumothorax is a life-threatening condition caused by air within the pleural
space that displaces mediastinal structures and compromises cardiopulmonary function. It is characterized by rapid-
onset dyspnea, tachycardia, tachypnea, hypotension, and distension of the neck veins. Treatment should be initiated
immediately with needle thoracostomy.

537. Sepsis Patients with septic shock first require aggressive volume resuscitation with intravenous 0.9%
saline prior to the initiation of vasopressors to restore adequate tissue perfusion.

538. Acute Respiratory Failure Hypoxemia can be caused by reduced inspired oxygen tension,
hypoventilation, diffusion limitation, shunt, and V/Q mismatch. Hypoventilation is associated with a normal A-a gradient
and respiratory acidosis.
539. Lung Cancer Squamous cell carcinoma of the lung usually arises in the central tracheobronchial tree
(e.g. hilar mass) and is often associated with cough, hemoptysis, dyspnea, and hypercalcemia (due to parathyroid
hormone-related protein release). In contrast, small cell carcinoma of the lung causes other paraneoplastic syndromes
(e.g. ACTH production, syndrome of inappropriate antidiuretic hormone secretion), and adenocarcinoma of the lung
typically causes peripheral lung lesions.

540. Lung Cancer Superior pulmonary sulcus tumors are malignant lung neoplasms that arise in the
superior portion of the lung. They most commonly present with shoulder pain, Horner syndrome, arm pain, and/or hand
weakness.
541. Acute Respiratory Failure Pulmonary edema causes hypoxemia due to right-to-left intrapulmonary
shunting, an extreme ventilation/perfusion (V/Q) mismatch. When the edema is diffuse, alveolar ventilation is zero
throughout much of the lungs and the hypoxemia does not correct with supplemental O2. As with any type of V/Q
mismatch, pulmonary edema leads to an increase in the alveolar-arterial O2 gradient. It also causes stiffening of the
lungs and decreased lung compliance.

542. Pulmonary Embolism Massive pulmonary embolism is likely in a postoperative patient with
hypotension, jugular venous distension, and new-onset right bundle branch block.

543. Metabolic Alkalosis Severe vomiting characteristically causes hypokalemic, hypochloremic metabolic
alkalosis. The metabolic alkalosis is initiated by loss of gastric H, worsened by hypovolemia-induced activation of the
renin-angiotensin-aldosterone system, and perpetuated by profound total body Cl depletion leading to hypochloremia
and impaired renal bicarbonate excretion. Urine Na and Cl are low due to total body depletion and aldosterone-
mediated renal tubular reabsorption. Repletion of volume and Cl with normal saline corrects the metabolic alkalosis
(saline responsive).

544. Metabolic Acidosis Nonanion gap metabolic acidosis (NAGMA) results from the loss of bicarbonate
(HCO3). Because exocrine pancreatic secretions are high in HCO3, NAGMA is expected with large-volume fluid losses
from the pancreas (e.g. pancreatic duct leak) or small intestine (e.g. high ileostomy output, enterocutaneous fistula).

545. Blunt Abdominal Trauma Blunt trauma (e.g. direct blow to the flank) can cause renal injury.
Concerning clinical findings (e.g. flank pain/ecchymosis) should prompt CT scan of the abdomen and pelvis, regardless of
whether hematuria is present.

546. Blunt Abdominal Trauma Blunt trauma to a full bladder can cause it to rupture at the weakest
point, the dome. Diversion of urine from the urinary tract (e.g. inability to void) into the peritoneal cavity can cause
urinary ascites and increased blood urea nitrogen and creatinine from peritoneal reabsorption.

547. Respiratory Alkalosis Patients can develop respiratory alkalosis with a high respiratory rate and
normal oxygen saturation due to inadequate pain control. Patients who take opioids chronically often develop tolerance
and require increased doses of opioids or multimodal strategies to appropriately control acute pain.

548. Urinary Tract Infection Renal and perinephric abscesses manifest with insidious onset of flank pain and
systemic symptoms (e.g. fever, weight loss), typically in patients with a history of urinary tract infection or extrarenal
infection (e.g. bacteremia) in the prior 1-2 months. In most cases, the urinalysis demonstrates pyuria, bacteriuria, and
proteinuria, but it may remain normal if the abscess is not in contact with the collecting ducts.

549. Polycystic Kidney Disease Hypertension is one of the earliest clinical manifestations of autosomal
dominant polycystic kidney disease. It likely results from cyst expansion leading to localized renal ischemia and
consequent increased renin production with activation of the renin-angiotensin-aldosterone system. Therefore, the
hypertension is best treated with ACE inhibitors (e.g. lisinopril).

550. Polycystic Kidney Disease Autosomal dominant polycystic kidney disease commonly presents with
hypertension, hematuria, and recurrent flank pain in patients in their 30s or 40s. Treatment is mostly supportive,
 although vasopressin-2 receptor antagonists (e.g. tolvaptan) may slow disease progression in some patients.

551. Renal Vein Thrombosis Acute renal vein thrombosis presents with hematuria, renovascular congestion,
and flank pain. The most common causes are nephrotic syndrome, malignancy, and trauma. Diagnosis can be confirmed
by CT or MR angiography or renal venography.

552. Renal Artery Stenosis Renal artery stenosis (RAS) can occur in the renal allograft, typically within 2
years of transplant. Like other forms of RAS, suggestive findings include persistently elevated blood pressure, decline in
renal function with the addition of ACE inhibitors, a lateralizing abdominal bruit, and recurrent flash pulmonary edema.
The diagnosis is made with renal vascular imaging (e.g. renal Doppler ultrasonography).

553. Renal Artery Stenosis Severe hypertension and recurrent flash pulmonary edema in the setting of
diffuse atherosclerosis suggests renal artery stenosis. Associated findings can include chronic kidney disease and
evidence of secondary hyperaldosteronism (hypokalemia, elevated serum bicarbonate); urinalysis is typically bland. The
diagnosis is confirmed with renal imaging (e.g. renal ultrasound with Doppler).

554. Renal Artery Stenosis Renal artery stenosis typically presents with uncontrolled hypertension. A
lateralizing abdominal bruit is a highly specific examination finding; atrophy of the affected kidney may be seen on
imaging. Hypoperfusion of the post-stenotic kidney results in increased local renin secretion, leading to activation of the
renin-angiotensin-aldosterone system and secondary hyperaldosteronism. Renin secretion by the unaffected kidney is
suppressed.
555. Von Hippel Lindau Disease Von Hippel-Lindau disease is an autosomal dominant disorder resulting
in benign and malignant multiorgan tumors. The most common tumors are hemangioblastomas of the central nervous
system and retina. Other common manifestations include renal cell carcinoma (often preceded by the formation of
premalignant renal cysts) and pheochromocytoma.

556. Bladder Cancer Bladder cancer is common in older adults and often presents with hematuria, voiding
symptoms (e.g. dysuria, frequency), and/or hydronephrosis with flank pain. Urgent cystoscopy is required to visualize the
bladder wall and to biopsy suspicious masses.

557. Bladder Cancer Bladder cancer often presents with painless hematuria that lasts throughout micturition
in an adult age > 40. Urinalysis should be performed to confirm hematuria (> 3 red blood cells/hpf) and to rule out
infection/glomerulonephritis. Those with no clear cause for hematuria require urgent evaluation with cystoscopy to
visualize the bladder for lesions.

558. Renal Cell Carcinoma Polycythemia with high circulating erythropoietin (EPO) levels (secondary
polycythemia) is usually due to tumors that produce EPO (e.g. renal cell carcinoma) or chronic hypoxia (e.g.
cardiopulmonary disease, obstructive sleep apnea). Individuals with secondary polycythemia and no evidence of hypoxia
should undergo abdominal CT scan to evaluate for renal cell carcinoma.

559. Renal Cell Carcinoma Renal cell carcinoma is common in older patients who smoke. It often presents
with weight loss, hematuria, firm/nontender flank mass, and/or intermittent fever.

560. Urinary Tract Obstruction Urethral stricture is a fibrotic narrowing of the urethra. Common causes
include urethral trauma, infection, and radiotherapy. Symptoms include weak or spraying urine flow and incomplete
emptying. Postvoid residual volume is increased. The diagnosis is confirmed on urethrography or cystourethroscopy;
treatment includes urethral dilation or surgical urethroplasty.

561. Renal Calculi Urologic consultation is advised for ureterolithiasis associated with urosepsis, anuria,
acute kidney injury, or refractory pain. Consultation is also warranted for large kidney stones (> 10 mm in diameter) that
are unlikely to pass without additional intervention (e.g. lithotripsy). Most stones < 5 mm pass spontaneously, and α
blockers (e.g. tamsulosin) can be used to facilitate passage (especially for intermediate-sized stones 6-10 mm).
562. Renal Calculi Magnesium ammonium phosphate (struvite) causes large kidney stones in patients who
have recurrent upper urinary tract infection with urease-producing organisms (e.g. Proteus, Klebsiella). Antibiotics alone
do not eliminate struvite stones, which can harbor bacteria, leading to further infection. Stone removal is usually
required.
563. Renal Calculi Excess urinary excretion of uric acid and low urine pH can lead to supersaturation of
urine and the formation of uric acid stones. Risk factors include gout, obesity, diabetes mellitus/metabolic syndrome,
chronic diarrhea (due to acidification of the urine), and increased systemic uric acid production. Alkalization of the urine
with potassium citrate effectively dissolves the stones.

564. Hyponatremia Hyponatremia can cause cellular swelling and cerebral edema. Symptoms reflect
elevated intracranial pressure; mild/moderate symptoms include headache, nausea, and confusion, whereas severe
symptoms include seizure, coma, and respiratory arrest. Acute hyponatremia (< 48 hr duration) is poorly tolerated, and
patients are at elevated risk of brain herniation; therefore, patients with any symptoms should receive hypertonic 3%
saline.
565. Renal Calculi α1 receptor blockers such as tamsulosin act on the distal ureter, lowering muscle tone
and reducing reflex ureteral spasm secondary to stone impaction. These agents facilitate stone passage and reduce the
need for analgesics.

566. Urinary Retention Patients with postoperative urinary retention often have suprapubic discomfort
and fullness, along with hypertension and tachycardia (i.e. sympathetic stimulation); portable bladder ultrasound can
confirm the diagnosis.

567. Urinary Retention Acute urinary retention (AUR) is common in elderly men, especially in the setting
of underlying benign prostatic hyperplasia. The risk of AUR is further increased during the postoperative period.
Diagnosis is made using bladder ultrasound.

568. Prerenal Azotemia Intravascular volume depletion is a common cause of prerenal acute kidney
injury (AKI). Patients typically have an elevated blood urea nitrogen/creatinine ratio (> 20:1), oliguria, and unremarkable
urine sediment. Administration of intravenous fluid restores renal perfusion and corrects the AKI.

569. Bladder Trauma Blunt lower abdominal trauma can rupture the bladder at its weakest part (i.e. dome),
spilling urine into the intraperitoneal cavity. Common clinical findings include hematuria, suprapubic tenderness,
difficulty voiding, and associated pelvic fracture.

570. Urinary Retention Drugs with anticholinergic properties can cause acute urinary retention by
preventing detrusor muscle contraction and urinary sphincter relaxation. The treatment involves urinary catheterization
and discontinuing the medication.

571. Renal Artery Stenosis In adults, fibromuscular dysplasia most commonly affects women. Headaches
due to internal carotid artery stenosis and secondary hypertension due to renal artery stenosis are common
presentations. Accompanying bruits may be found in the neck and abdomen.

572. Renal Calculi Oxalate absorption is increased in Crohn disease and all other intestinal diseases causing
fat malabsorption. Increased absorption is the most common cause of symptomatic hyperoxaluria and oxalate stone
formation.
573. Renal Trauma Blunt trauma can cause renal injury. Concerning clinical findings include flank pain and
ecchymosis, costovertebral area tenderness, and hematuria. These findings, or a concerning mechanism of injury, should
prompt CT scan of the abdomen and pelvis.

574. Urethral Injury Pelvic fractures in men may be complicated by posterior urethral injury. Patients with
suspected urethral injury (e.g. blood at the urethral meatus, high-riding prostate) should undergo retrograde
urethrography.
575. Bladder Trauma Suprapubic pain and gross hematuria with associated pelvic fracture are concerning for
bladder injury. Because of urine containment within adjacent tissues, extraperitoneal bladder rupture typically causes
localized (vs diffuse abdominal) symptoms and a negative examination with Focused Assessment with Sonography for
Trauma.
576. Bladder Cancer Bladder cancer often causes hematuria, voiding symptoms (e.g. dysuria, urgency,
frequency), and/or suprapubic pain. Patients who have no clear source (e.g. cystitis) for these symptoms require urgent
workup with cystoscopy.

577. Renal Calculi Most ureteral stones < 5 mm in diameter pass spontaneously; increased oral fluid intake
is recommended to ensure adequate flow of dilute urine. α blockers can be used to facilitate passage of larger stones (6-
10 mm). Urologic consultation is recommended for stones > 10 mm and for refractory pain, anuria, acute kidney injury,
or signs of urosepsis.

578. Bursitis During a joint or bursal aspiration or injection, introduction of skin flora may result in septic
bursitis or septic arthritis, presenting as worsening pain several days following the procedure. Diagnostic aspiration of
the joint or bursa is necessary to assess for infection.

579. Bursitis Gout can cause acute bursal (e.g. prepatellar, olecranon) inflammation, chronic bursal swelling,
or tophus deposition in the bursa. Tophus induces chronic inflammation in the surrounding soft tissue and bones, which
can result in erosions and overhanging edges of cortical bone on imaging.

580. Colles Fracture Distal radius fractures with neurovascular compromise (e.g. absent radial pulse,
diminished median nerve sensation) should undergo immediate reduction.

581. Bursitis Septic prepatellar bursitis is characterized by acute erythema, warmth, and pain accompanying
bursal swelling. It is usually caused by skin breakage that allows entry of skin floras (e.g. Staphylococcus). Bursal fluid
analysis is needed to confirm the diagnosis. Treatment includes systemic antibiotics.

582. Hip Fracture Hip dislocation should be reduced within 6 hours of injury to minimize the risk of
osteonecrosis of the femoral head. Dislocation without associated fracture is usually managed with closed (i.e.
nonoperative) reduction, whereas dislocation with fracture warrants open (i.e. operative) reduction.

583. Clavicle Fracture Patients with seemingly minor blunt chest trauma (BCT) (e.g. clavicular fracture)
can have serious intrathoracic injury (e.g. subclavian vessel injury). Abnormalities on screening tests (e.g. chest x-ray) in
stabilized patients with BCT should prompt additional studies (e.g. CT scan of the chest) to evaluate for intrathoracic
injuries.
584. Adhesive Capsulitis Adhesive capsulitis results from contracture of the glenohumeral joint capsule
and presents with gradual onset shoulder pain and reduced active and passive range of motion. Treatment includes
gentle range of motion exercises; adjunctive measures include nonsteroidal anti-inflammatory drugs and corticosteroid
injections.
585. Hip Fracture Femoral neck fractures are most common in elderly individuals, typically presenting with
hip pain after a fall. Common x-ray findings include shortening of the femoral neck, disruption of the normal cortical
contour, and irregular lucency at the fracture plane. Femoral neck fractures have a significant risk of complications (e.g.
secondary instability, malunion), and surgical repair is indicated for most patients.

586. Tarsal Tunnel Syndrome Tarsal tunnel syndrome is caused by posterior tibial nerve compression beneath
the flexor retinaculum in the medial ankle. It presents with burning pain or numbness in the posteromedial ankle, heel,
sole, and toes, which is elicited by tapping on the nerve (i.e. Tinel sign).

587. Dupuytren Contracture Dupuytren contracture results from progressive palmar fascia fibrosis, leading to
puckering of the skin and fibrotic nodule and cord formation along the flexor tendons. Patients develop contractures that
limit extension at the metacarpophalangeal and proximal interphalangeal joints. The diagnosis is made clinically; no
 imaging is needed.

588. Acromioclavicular Injuries Acromioclavicular (AC) joint sprain results from direct trauma to the
superior or lateral shoulder. Examination shows maximal tenderness over the AC joint and pain with adduction of the
arm across the torso. X-rays can assess the degree of sprain and evaluate for concomitant clavicular or humeral
fractures.
589. Rotator Cuff Shoulder dislocation is commonly associated with rotator cuff injury (RCI), which
presents as shoulder pain and difficulty with abduction. RCI can cause weakness but not sensory loss.

590. Shoulder Dislocation Acute glenohumeral dislocation is often complicated by additional injuries,
including axillary nerve injury, fracture, and rotator cuff tear. Humeral neck fractures are associated with an increased
risk for avascular necrosis, and closed reduction may lead to further displacement of the fracture. Therefore, dislocation
associated with humeral neck fracture requires open surgical repair.

591. Shoulder Dislocation Patients who experience shoulder dislocation are often at increased risk for
recurrent dislocation due to labral tears (i.e. Bankart lesion), ligamentous laxity due to overuse, and underlying
multidirectional joint instability (i.e. excessive, symptomatic, and involuntary laxity of the joint capsule in > 1 direction).

592. Plantar Fasciitis Plantar fasciitis is a degenerative condition of the plantar aponeurosis at its insertion at
the calcaneus caused by overuse. Pain is typically worsened by prolonged standing and is located at the anteromedial
heel. First-line treatments include activity modification, physical therapy (stretching), and padded heel inserts. Calcaneal
spurs are incidental and do not require treatment.

593. Myositis Ossificans Myositis ossificans is characterized by the formation of lamellar bone in
extraskeletal tissues (i.e. heterotopic ossification). It is triggered by severe or recurrent trauma and presents as a painful,
firm, mobile mass with local swelling. Alkaline phosphatase and inflammatory markers (e.g. erythrocyte sedimentation
rate) may be elevated. X-ray may show calcification with radiolucent zones.

594. Stress Fractures Calcaneal stress fracture is caused by repetitive microtrauma to the calcaneus (e.g.
abrupt increase in running). On examination, the pain is elicited by medial-lateral squeezing of the calcaneus, and the
diagnosis is confirmed with imaging (x-ray or MRI).

595. Ganglion Cyst Ganglion cyst is a connective tissue outpouching arising from tendon sheaths and joint
structures. It presents as a rubbery, mobile, transilluminating nodule, most commonly at the wrist. Most ganglion cysts
resolve spontaneously, and asymptomatic cysts can be observed.

596. Tendon Injury The diagnosis of acute Achilles tendon rupture can be easily missed and is best evaluated
on physical examination with the calf squeeze test, which simulates gastrocnemius contraction. Absent foot plantar
flexion in response to calf squeeze is consistent with Achilles tendon rupture.

597. Hip Fracture Femoral neck and intertrochanteric fractures are the most common hip fractures in
older adults and most typically occur due to mechanical falls. Examination findings include shortening and external
rotation of the leg compared with the contralateral side.

598. Hip Fracture Posterior hip dislocation commonly occurs in head-on motor vehicle collisions in which
the knee strikes the dashboard. The leg appears shortened and internally rotated. Complications include sciatic nerve
injury (e.g. impaired dorsiflexion) and arterial injury with avascular necrosis of the femoral head.

599. Septic Arthritis Initial treatment of septic arthritis includes intravenous antibiotics and adequate
drainage of purulent material via needle aspiration, arthroscopic irrigation, or open surgical drainage. Serial procedures
are often required to completely clear the infection.
600. Knee Dislocation Knee dislocation can cause limb-threatening injury to the popliteal artery.
Meticulous vascular examination, including measurement of the ankle-brachial index, is necessary for ruling out vascular
injury.
601. Anorexia Nervosa A dietary history to assess for anorexia nervosa should be obtained in any
patient with a stress fracture, low body weight, and distress at having to limit physical activity. Patients with anorexia
nervosa are at risk for stress fractures due to decreased bone mineral density.

602. Bursitis Greater trochanteric pain syndrome presents with lateral hip pain and tenderness over the
greater trochanter during flexion. Initial treatment includes heat, activity modification, and nonsteroidal anti-
inflammatory drugs. Patients with persistent symptoms may benefit from local corticosteroid injection.

603. Iliotibial Band Syndrome Iliotibial (IT) band syndrome is characterized by poorly localized lateral
knee pain. It is common in inexperienced runners starting a new or more strenuous training regimen. Examination shows
tenderness proximal to the joint line; pressure over the IT band just proximal to the lateral femoral epicondyle during
flexion of the knee reproduces the pain.

604. Scoliosis Adolescent idiopathic scoliosis is defined as lateral curvature of the spine without a
known etiology in a child age > 10. Forward bend test reveals an asymmetric thoracic or lumbar prominence. The first
step in evaluation is x-ray of the spine to determine the degree of curvature and assess skeletal maturity.

605. Pelvis Fracture Pelvic fractures, especially those with pelvic ring disruption, can cause life-threatening
hemorrhage from vascular (e.g. venous plexus) injury. Pelvic binder application can decrease pelvic volume and promote
tamponade of bleeding.

606. Salter-Harris Fracture A Salter-Harris type III (juvenile Tillaux fracture) is characterized by fracture of
the distal tibial epiphysis and lateral physis (i.e. growth plate) and most commonly occurs in adolescents when the physis
is partially fused. Injury to the growth plate can cause growth arrest and lead to persistent limb-length discrepancy.

607. Upper Extremity Long Bone Fracture Buckle fractures are common in children and typically occur at
the distal radius and/or ulna due to a fall onto an outstretched hand. X-ray is diagnostic and shows bulging of the bony
cortex.
608. Colles Fracture Distal radius fracture with dorsal displacement can cause median nerve compression,
resulting in acute carpal tunnel syndrome symptoms, including paresthesia of the lateral 3.5 digits and impaired thumb
abduction. In addition, if compression occurs proximal to the tunnel, the palmar cutaneous branch of the median nerve
may be affected, leading to decreased sensation over the anterolateral hand.

609. Ankle Trauma Lateral ankle sprains are typically caused by forceful inversion of the foot. The anterior
talofibular ligament is most commonly injured. If there is tenderness only over the ligaments distal to the lateral malleoli
and the patient can bear weight, conservative management (e.g. compression bandage or brace, ice packs, crutches to
reduce weightbearing) without imaging is appropriate.

610. Ankle Trauma Ankle pain after trauma may be caused by a sprain or fracture. The Ottawa ankle rules
are used to help determine which patients require imaging. X-ray of the ankle is indicated for patients with pain in the
malleolar region in association with either 1) bony tenderness at the posterior margin or tip of the lateral or medial
malleolus or 2) inability to bear weight.

611. Ganglion Cyst Ganglion cysts are mobile, nontender swellings that occur most commonly at the dorsal
surface of the wrist. The diagnosis is usually obvious on inspection and can be confirmed on transillumination of the
mass. Most ganglion cysts resolve spontaneously and require no treatment.

612. Amputation Phantom limb pain is common following extremity amputation. The neuropathic pain,
which is perceived in the absent portion of the limb, is best managed with a multimodal pain regimen consisting of
 pharmacotherapy and adjuvant therapies.

613. Amputation Post-traumatic neuromas are due to the transection of nerve fibers and form over
several weeks to months following injury or amputation. They cause pain with local pressure that can complicate fittings
for amputational prosthetics. Injection of a local anesthetic can provide transient pain relief and confirm the diagnosis.
Management typically involves excision of the neuroma.

614. Plantar Fasciitis Plantar fasciitis is characterized by inflammation and degeneration of the plantar
aponeurosis (deep plantar fascia), a thick, fibrous band that extends from the calcaneus to the toes and supports the
longitudinal arch of the foot. It presents with chronic pain at the sole of the foot that is worse with weight bearing.

615. Osteomyelitis Chronic osteomyelitis may lead to fracture nonunion. Common symptoms include
intermittent pain and swelling and sinus tract formation. Open bone biopsy is recommended for microbiologic
assessment, and treatment requires surgical debridement of the infected and necrotic bone.

616. Bone Tumor Paget disease of bone is associated with increased bone remodeling, which dramatically
increases the risk of osteosarcoma. Most cases present with pain, soft tissue swelling, and hallmark radiographic findings
(e.g. destructive bone lesion, sunburst periosteal reaction, Codman triangle).

617. Bone Tumor Osteosarcoma is a primary bone tumor that is often associated with inherited genetic
mutations to the RB1 gene, which causes retinoblastoma, and the TP53 gene, which is linked to Li-Fraumeni syndrome.

618. Quadriceps Muscle And Tendon Injuries Sudden, forceful contraction of the quadriceps muscle can cause
rupture of the quadriceps-patellar tendon complex. Symptoms include an audible pop, rapid swelling, and inability to
actively extend the knee against gravity. In tears of the quadriceps tendon (proximal to the patella) the patella rides low,
with a palpable defect above the patella.

619. Compartment Syndrome Compartment syndrome is caused by increased pressure within an

enclosed fascial space that limits perfusion. Common causes include fracture, crush injury, severe burns, and arterial
reperfusion procedures; patients who are on anticoagulation or have a bleeding diathesis are at increased risk. Clinical
features include pain, paresthesias, loss of sensation, and motor weakness. Diagnosis is confirmed by measuring
compartment pressures.

620. Osteoarthritis Management of osteoarthritis of the knee should include weight loss, regular activity,
and exercises to strengthen the quadriceps muscle. Simple analgesics may also be helpful. If conservative management is
inadequate, injectable glucocorticoids may relieve symptoms. Total knee arthroplasty is indicated for those who fail less
aggressive measures.

621. Slipped Capital Femoral Epiphysis Slipped capital femoral epiphysis is most common in obese
adolescents and occurs when the proximal femur is displaced relative to the epiphysis along the growth plate. Knee pain
may be the only presenting symptom. Supportive examination findings include limited hip flexion and internal rotation.

622. Slipped Capital Femoral Epiphysis Slipped capital femoral epiphysis occurs when excessive
shearing at the proximal femoral physis weakens the growth plate, causing displacement of the proximal femur
diaphysis. Patients are classically obese adolescents with chronic, dull pain along the thigh or knee that worsens with
activity.
623. Osteomyelitis Pediatric acute osteomyelitis is most commonly caused by hematogenous spread of
bacteria to the metaphysis of long bones. Patients have fever, refusal to bear weight, and point tenderness over the
affected bone.
624. Osteoarthritis Initial management of osteoarthritis of the knee includes weight loss, regular moderate
activity, and topical or oral nonsteroidal anti-inflammatory drugs. In addition, exercises to strengthen the quadriceps
muscles can reduce abnormal loading on the joint and protect the articular cartilage from further stress.
625. Osteoarthritis Osteoarthritis of the hip is characterized by chronic pain in the groin, buttock, or lateral
hip that is worse with activity and weight bearing. Examination often shows decreased rotational range of motion. X-ray
reveals loss of the normal joint space, periarticular osteophytes, and sclerosis of the acetabular surface.

626. Plantar Fasciitis Plantar fasciitis presents with pain at the sole of the foot that is worse with prolonged
weight bearing or with the first steps of the day. The pain may be reproduced by palpation of the insertion of the
aponeurosis on the calcaneus with dorsiflexion of the toes. X-ray may show calcifications in the proximal fascia (heel
spurs), but this is neither sensitive nor specific.

627. Patellar Dislocation Patellar dislocation usually occurs after quick, lateral movements on a flexed
knee. Lateral dislocation is most common. Risk factors include age < 20, joint laxity, lower extremity malalignment, and
patellar subluxation. Examination shows reduced range of motion and lateral displacement of the patella out of the
trochlea.
628. Osteoporosis Osteoporosis in a young or middle-aged man suggests a secondary cause. Bone loss is
common in celiac disease due to malabsorption of vitamin D. Manifestations may include asymptomatic
osteopenia/osteoporosis or osteomalacia with bone pain, muscle weakness, and impaired ambulation.

629. Patellofemoral Syndrome Patellofemoral pain syndrome is a common cause of anterior knee pain
in young women. It is usually due to chronic overuse or malalignment. The pain is provoked by maneuvers (e.g.
squatting) that involve contraction of the quadriceps with the knee in flexion. Initial management includes activity
modification, nonsteroidal anti-inflammatory drugs, and stretching and strengthening exercises.

630. Bursitis Prepatellar bursitis is characterized by anterior knee pain, tenderness, erythema, and localized
swelling and is common in occupations requiring repetitive kneeling. Bursal fluid analysis should be performed to exclude
infection.
631. Knee Trauma Anterior cruciate ligament injuries are common in sports requiring rapid direction
changes or twisting movements of the lower extremity. They usually present with rapid onset of pain and swelling with
hemarthrosis. Examination findings include laxity of anterior motion of the tibia relative to the femur.

632. Charcot Joint Neurogenic arthropathy (Charcot joint) is due to abnormal lower extremity sensation
and proprioception, leading to altered weight bearing, mechanical stresses, and recurrent trauma. It is most common in
patients with diabetic neuropathy. It can cause impaired ambulation, but pain is typically mild. Examination shows
deformity of the foot, and x-ray reveals bony destruction, osteophyte formation, and loss of joint spaces.

633. Rotator Cuff Rotator cuff tears cause pain and weakness at the shoulder. With the arm abducted over
the head, the patient may be unable to lower the arm smoothly (drop arm test). An MRI scan can confirm the diagnosis.

634. Baker Cyst A popliteal (Baker) cyst is due to extrusion of synovial fluid from the knee joint into the
gastrocnemius or semimembranosus bursa, and is most common in patients with underlying arthritis. Popliteal cysts may
present as a painless bulge in the popliteal space, but cyst rupture can cause acute pain in the calf.

635. Osteonecrosis Osteonecrosis (avascular necrosis) of the femoral head is a common complication of
glucocorticoid use. It is characterized by progressive hip pain, leading to reduced range of motion and joint instability. X-
rays will often be normal, and MRI is a more sensitive test.

636. Bursitis Greater trochanteric pain syndrome is an overuse syndrome involving the tendons of the gluteus
medius and minimus at the greater trochanter. It presents with chronic lateral hip pain that is worsened with repetitive
hip flexion or lying on the affected side. Physical examination shows local tenderness over the greater trochanter.

637. Stress Fractures Stress fractures of the metatarsals are associated with a sudden increase in activity and
are common in athletes and military recruits; the second metatarsal is most commonly injured. Initial treatment includes
rest and simple analgesics. Stress fractures of the fifth metatarsal are at increased risk for nonunion and warrant more
 aggressive treatment.

638. Hyperkalemia Succinylcholine is a depolarizing neuromuscular blocker that can cause life-threatening
hyperkalemia in patients with a condition leading to upregulation of postsynaptic acetylcholine receptors (e.g. skeletal
muscle trauma, burn injury, stroke). Nondepolarizing neuromuscular blocking agents (e.g. vecuronium, rocuronium)
should be used with these patients.

639. Vertebral Compression Fracture Acute vertebral compression fracture can be caused by twisting, lifting,
or trauma and presents with back pain and vertebral point tenderness. It typically occurs in patients with osteoporosis or
other conditions associated with decreased bone mineral density.

640. Osteomyelitis Tenderness to gentle percussion over the spinous process of the involved vertebra is the
most reliable sign for spinal osteomyelitis. Pain is not relieved with rest. Fever and leukocytosis are unreliable findings.
The erythrocyte sedimentation rate is grossly elevated. MRI is the most sensitive diagnostic study. There should be a very
high index of suspicion for vertebral osteomyelitis in patients with a history of injection drug use or recent distant site
infection (e.g. urinary tract infection).

641. Back Pain Most patients with acute, uncomplicated low back pain experience spontaneous
resolution of their symptoms in the first few weeks. Patients should be advised to continue moderate activity.
Nonsteroidal anti-inflammatory drugs are preferred as initial management.

642. Knee Trauma Acute knee pain associated with catching or reduced range of motion suggests a
meniscal tear. Persistent symptoms in patients with suspected meniscal injury should be evaluated by MRI, and surgical
consultation is advised for significant tears.

643. Osteonecrosis Osteonecrosis (aseptic necrosis) of the femoral head is a common complication of sickle
cell disease and presents with hip pain, reduced range of motion, and normal findings on initial x-rays. It is due to
occlusion of end arteries supplying the femoral head, leading to necrosis and collapse of the periarticular bone and
cartilage.
644. De Quervain Tenosynovitis De Quervain tendinopathy presents with lateral wrist pain over the
tendons of the abductor pollicis longus and extensor pollicis brevis. It is most common in women age 30-50, with an
increased frequency during the postpartum period. Examination shows tenderness at the radial side of the wrist and a
positive Finkelstein test (reproduction of pain on adduction of the wrist with the fingers closed over the thumb).

645. Knee Trauma Tears of the medial meniscus often result from twisting injuries with the foot in a fixed
position. Associated symptoms can include reduced extension, a sensation of instability, and a knee effusion.
Examination reveals palpable locking or catching when the joint is rotated or extended while under load. Diagnosis is
confirmed with MRI or arthroscopy.

646. Knee Trauma Medial collateral ligament tear is caused by valgus stress or severe twisting injury and
can be associated with injury to the medial meniscus. Findings include tenderness at the medial knee and valgus laxity.
MRI is the most sensitive test, and most patients are managed nonoperatively.

647. Stress Fractures Tibial stress fractures are caused by repeated tension or compression without adequate
rest and occur most commonly in athletes or others who suddenly increase their activity. Findings include subacute,
localized, activity-related pain; swelling; and point tenderness on palpation. X-rays are frequently normal.

648. Hip Fracture Older patients with hip fracture should undergo definitive surgical correction as soon as
reasonably possible. However, surgery may be delayed up to 72 hours to evaluate surgical risk and ensure medical
stability.
649. Scaphoid Fracture Arterial supply to the scaphoid enters at the distal pole; fracture can disrupt flow
to the proximal segment, leading to avascular necrosis and nonunion. Nondisplaced fractures may not be immediately
visible on x-ray. If initial x-rays are negative, CT scan or MRI is recommended, or the wrist should be immobilized and x-
 rays repeated after 7-10 days.

650. Clavicle Fracture Clavicle fracture can injure the underlying brachial plexus and subclavian artery.
Hard signs of arterial injury (e.g. absent pulses, distal ischemia) require immediate surgical intervention. Soft signs of
vascular injury (e.g. unexplained hypotension, stable hematoma, reduced pulse) warrant CT angiography for further
evaluation.
651. Upper Extremity Long Bone Fracture Displaced supracondylar fractures of the humerus most
commonly present after a fall onto an outstretched hand with posterior displacement of the distal humerus fragment.
The anteriorly displaced proximal humerus fragment can entrap the brachial artery and median nerve, which pass
anterior to the humerus.

652. Compartment Syndrome Patients with compartment syndrome have severe pain, pain with
passive range of motion, and paresthesia. Sensory and motor deficits occur in later stages. Pallor and loss of limb pulses
are uncommon findings. Compartment pressures must be measured immediately if the index of suspicion is very high.
Fasciotomy is the treatment of choice.

653. Scaphoid Fracture Displaced scaphoid fractures should be considered for surgical intervention.
Wrist immobilization with a cast can be considered for nondisplaced fractures, but patients should be monitored with
serial x-ray to rule out osteonecrosis of the proximal segment and nonunion of the fracture.

654. Upper Extremity Long Bone Fracture Midshaft humeral fractures occur due to direct blows to the arm
and can cause pain, swelling, deformity, and shortening. Associated radial nerve neurapraxia is common and often
resolves with appropriate management of the fracture. Many midshaft humeral fractures can be treated nonsurgically.
Indications for open reduction and surgical exploration include open fractures, neurovascular compromise, and
significant displacement.

655. Fat Embolism Fat embolism syndrome can occur following the fracture of large, marrow-rich bones
(e.g. the femur). Microvascular obstruction in the pulmonary circulation can lead to respiratory distress; obstruction in
the cerebral circulation may cause neurologic dysfunction, including confusion and focal deficits.

656. Rotator Cuff Rotator cuff tears occur most commonly in patients age > 40, often after a fall on an
outstretched arm. These injuries are characterized by pain and weakness with abduction and external rotation of the
humerus. MRI can confirm the diagnosis.

657. Rotator Cuff Rotator cuff tendinopathy (RCT) is most common in patients who perform repetitive arm
movement above shoulder height. It presents with subacute pain on abduction. Impingement syndrome refers to
compression of soft tissue structures between the humeral head and acromion and is a characteristic feature of RCT.

658. Bone Tumor Giant cell tumor of bone is a benign but locally destructive neoplasm that is most
common at the epiphysis of long bones in young adults. Most patients have local manifestations (e.g. pain, swelling), but
pulmonary metastasis and malignant transformation may occur. X-ray shows an eccentric lytic lesion, often resembling
soap bubbles. The diagnosis is confirmed with biopsy, and surgery is first-line treatment.

659. Patient Safety Errors in medication reconciliation (i.e. the process of reviewing and updating the
patient's prescription and over-the-counter medications) occur frequently during transfer of care (e.g. hospital
admission). Prevention includes increasing checkpoints (i.e. redundancy) by having at least 2 providers independently
reconcile all medications, involving interprofessional staff (e.g. pharmacist review), and repeating verification prior to
continuing home medications.

660. Patient Safety Psychological safety strengthens safety culture by enabling team members to express
questions and concerns without fear and regardless of status. Team-based safety briefings, used by high-reliability
organizations (e.g. aviation), improve communication skills and psychological safety by encouraging collaborative
 discussion and monitoring.

661. Patient Safety Poor teamwork (including miscommunication) is a leading root cause of retained foreign
objects in surgical settings. Simulation training, adopted by high-reliability organizations, improves teamwork and safety
culture, promoting situational awareness, reduced hierarchical barriers, and closed-loop communication.

662. Patient Safety Misreading look-alike drug vials is a leading cause of medication error in operative
settings. Human factors engineering strategies can prevent such errors by designing systems that decrease human effort
and facilitate correct action. Examples include environmental design changes separating look-alike medications,
standardizing and simplifying processes, and using visual cues.

663. Patient Safety Communication breakdown during signout (e.g. omitted information during handoff
between providers) is a leading cause of transfer-of-care errors and can be prevented with standardized signout
processes (e.g. checklists, mnemonics) and redundancy (e.g. separate documentation of cross-coverage events).

664. Informed Consent Life-saving procedures (e.g. intubation) may be performed without informed
consent in emergencies, when obtaining consent is not possible. Informed refusal requires discussion of all the same
elements (e.g. diagnosis, proposed procedure, risks/benefits, alternatives, risks of refusal) required for informed
consent.
665. Informed Consent An exception to the requirement of informed consent is extension of an
authorized procedure if an unexpected complication arises that demands immediate treatment. However, this exception
does not cover procedures for unrelated issues that are not imminently life-threatening.

666. Decision Making Capacity Incapacitated patients may regain capacity as their condition improves.
These patients should be reassessed for capacity before health care decisions are made.