Advances in Surgery 47 (2013) 119–140

ADVANCES IN SURGERY

Appendicitis: Changing Perspectives

Pedro G.R. Teixeira, MD, Demetrios Demetriades, MD, PhD*

Division of Trauma and Acute Care Surgery, LAC and USC Medical Center, University of
Southern California, 2051 Marengo Street, IPT, Room C5L 100, Los Angeles, CA 90033-4525, USA

Keywords

Appendicitis
Laparoscopy
Nonoperative
Imaging
Key points

Neoplasms are uncommon, occurring in less than 1% of appendectomies.

A negative ultrasound is not adequate to rule out appendicitis and should be
followed by CT scan.

During pregnancy, MRI is a reasonable alternative to CT scan.

Nonoperative management with antibiotics is a safe initial treatment of uncom-
plicated appendicitis, with less complications but high failure rate.

Open and laparoscopic appendectomies provide similar results overall.

A negative appendectomy is associated with a significant incidence of fetal loss.

The increased morbidity associated with appendectomy delay suggests that
prompt surgical intervention remains the safest approach.

Routine incidental appendectomy should not be performed.

Interval appendectomy is not indicated because of risks of complications and
lack of clinical benefit.

Patients older than 40 years treated nonoperatively should have a colonoscopy
to rule out cancer or alternative diagnosis.

INTRODUCTION
Despite remarkable advances in medicine and surgery, appendicitis continues to
fascinate and challenge surgeons. Although records of the initial anatomic illus-
trations and descriptions of the vermiform appendix date back more than 500
years, it was not until the late nineteenth century that the inflammatory process
occurring in the right lower quadrant and its association with the appendix were
systematically described by Dr Reginald H. Fitz [1]. In his 1886 address to the
first meeting of the Association of the American Physicians, Dr Fitz presented

*Corresponding author. E-mail address: demetria@usc.edu

0065-3411/13/$ – see front matter

http://dx.doi.org/10.1016/j.yasu.2013.02.002 Ó 2013 Elsevier Inc. All rights reserved.
120 TEIXEIRA & DEMETRIADES

an elegant article entitled, ‘‘Perforating Inflammation of the Vermiform Appen-

dix; With Special Reference to Its Early Diagnosis and Treatment,’’ [1] and used
the term, appendicitis, for the first time [2]. Soon after, a series of important articles
by McBurney contributed significantly to consolidate appendicitis as a surgical
condition [3,4]. After several generations, McBurney’s remarks remain true:
‘‘I know of no localized disease which is capable of presenting such a variety
of pathologic processes. The real difficulty lies in estimating at an early period
the probable behavior of each individual case’’ [3].
More than 120 years later, significant scientific and technological progress
has revolutionized the field of surgery and resulted in a major improvement
in outcomes. In 1955, Cantrell and Stafford described the Johns Hopkins
25-year experience with appendicitis management [5]. The steady decrease in
mortality during that period was associated not only with the advent of antibi-
otics but also with better understanding of the physiopathology of sepsis and of
the importance of fluid and electrolyte resuscitation and the role of early ambu-
lation in prevention of pulmonary complications and venous thromboembolic
events. By the end of the 1950s, mortality for perforated appendicitis was in the
single digits and virtually no deaths occurred as a result of a nonperforated
appendicitis [5,6].
Despite these significant advances, however, there are still many unresolved
and controversial issues regarding the optimal diagnostic evaluation, need for
an operation, timing and operation technique, indication for incidental and in-
terval appendectomies, and optimal management strategy during pregnancy.
This article addresses these issues (Box 1).

EPIDEMIOLOGY
Appendectomy is the most commonly performed emergent abdominal opera-
tion in the United States [7]. The estimated incidence of acute appendicitis
has been reported as 11 per 10,000 population per year, with male and female
lifetime risks of appendicitis of 8.6% and 6.7%, respectively [8]. A more recent
epidemiologic investigation performed in California estimated a 9.0% lifetime
risk of appendicitis [9]. Overall, the peak incidence of appendicitis occurs dur-
ing the second decade of life [8,9]. There is a gender difference, however, with

Box 1: Controversial issues

Optimal diagnostic evaluation

Nonoperative management versus appendectomy

Appendectomy timing

Open versus laparoscopic technique

Interval appendectomy

Incidental appendectomy

Optimal management strategy during pregnancy
APPENDICITIS 121

earlier male peak incidence between 10 and 14 years of age compared with
female peak incidence at ages 15 to 19 [8].
The risk of perforation is higher at the extremes of age [9]. Patients younger
than 8 years or older than 45 years have an overall perforation incidence of
48% compared with 20% for patients between 8 and 45 years of age
(P<.001) [10].

INCIDENTAL MALIGNANCIES
After appendectomy for suspected acute appendicitis, the incidence of unex-
pected findings in histopathologic examination of the surgical specimens is
low. The overall incidence of malignancy is approximately 1%, with carcinoid
the most frequent [11–25].
In a recent study from the University of Southern California, a neoplasm
was identified in 31 of 4108 (0.75%) appendectomy specimens. Carcinoid
was the most common tumor, identified in 27 (87%) of the specimens with a
malignancy (Table 1).

DIAGNOSTIC ADVANCES AND CONTROVERSIES

History and physical examination remain powerful tools for the diagnosis of
acute appendicitis and in many instances may be enough to warrant surgical
exploration without additional imaging [26]. Alvarado described a scoring sys-
tem to predict the diagnosis of acute appendicitis based on symptoms, signs,
and laboratory findings [27]. This score, initially proposed to discriminate be-
tween patients who should be observed (scores 5 or 6) and those who should
be operated on (score 7 or higher), later became a tool to identify patients with
intermediate risk for appendicitis who need imaging investigation. A recent sys-
tematic review investigated the value of the Alvarado score for predicting acute
appendicitis and found that a score less than 5 can accurately rule out appen-
dicitis. It also found, however, that a score of 7 or higher is not specific enough
to warrant surgical exploration, suggesting that imaging investigation may be
necessary even for patients with a high score [28].
The use of imaging has been found to outperform the Alvarado score [29]
and decrease the incidence of negative appendectomies but had no impact in
decreasing perforation rate [30]. Currently, the imaging modalities most

Table 1
Neoplasms found in 4108 surgical specimens of patients undergoing appendectomy for acute
appendicitis at LAC þ USC Medical Center
Neoplasms Appendectomies for acute appendicitis (N ¼ 4108)
Neoplasms overall 31/4108 (0.75%)
Carcinoid tumor 27/31 (87%)
Mucinous tumor or uncertain 2/31 (7%)
malignant potential
Mucinous adenocarcinoma 1/31 (3%)
Granular cell tumor 1/31 (3%)
122 TEIXEIRA & DEMETRIADES

commonly used for the diagnosis of acute appendicitis include ultrasonogra-

phy, CT scan, and MRI.
On ultrasound, a normal appendix can be visualized at the right lower quad-
rant as a blind-ended tubular structure arising from the cecum. Its normal
diameter is 6 mm to 7 mm or less and the normal wall thickness is 2 mm or
less. When inflamed, the appendix becomes dilated, with thickened wall,
immobile, and noncompressible (Fig. 1) [31], which can be demonstrated
applying graded compression with the ultrasound probe (Fig. 2). Periappendic-
ular fluid and a fecalith may also be present (Figs. 3 and 4).
Ultrasound was found 78% to 83% sensitive and 83% to 93% specific for the
diagnosis of acute appendicitis [32,33]. Not being associated with ionizing radi-
ation remains the most important advantage of ultrasound compared with CT
scan. Ultrasound can be used for patients in whom additional imaging investi-
gations is considered necessary and is particularly valuable in women for eval-
uation of gynecologic problems, which have a clinical presentation similar to
appendicitis. Due to its lower sensitivity, however, a negative ultrasound
should not be relied on to exclude the diagnosis, and further imaging with
CT scan is advisable [34]. Poortman and colleagues [35] prospectively investi-
gated a diagnostic pathway in which ultrasound was the initial investigation
and was followed by CT scan if it was negative or inconclusive. This pathway
was 100% sensitive and 86% specific for appendicitis, suggesting that ultra-
sound can be safely used as the initial assessment of patients presenting with
right lower quadrant pain.
The most current iteration of the American College of Radiology Appropri-
ateness Criteria for right lower quadrant pain and suspected appendicitis sug-
gests that for adults CT scan provides higher sensitivity and specificity

Fig. 1. Ultrasound image demonstrating a sagittal section of a dilated, blind-ended structure

arising from the cecum, suggestive of acute appendicitis.
APPENDICITIS 123

Fig. 2. Ultrasound image demonstrating transverse section of a noncompressible tubular struc-

ture in the right lower quadrant. The increased diameter and noncompressibility suggest acute
appendicitis.

compared with ultrasound and decreases the incidence of negative appendec-

tomies. In children, graded-compression ultrasonography has sensitivity and
specificity comparable to those from CT scan without the potential harm of
ionizing radiation [36].

Fig. 3. Ultrasound image of a dilated appendix containing fecaliths.

124 TEIXEIRA & DEMETRIADES

Fig. 4. Ultrasound image of a dilated appendix with adjacent free fluid, suggestive of acute
appendicitis.

The CT scan findings of acute appendicitis include a dilated appendix, with

no luminal contrast or gas, associated with periappendicular fluid and fat
stranding (Fig. 5). CT scan is particularly useful in elucidating an alternative
diagnosis or identifying complications associated with appendicitis, such as
rupture, phlegmon, and abscess (Figs. 6 and 7).
Although MRI has been reported highly sensitive and specific for appendi-
citis [37,38] as well as cost effective [39], the value of this imaging modality
in the general population presenting with right lower quadrant pain and

Fig. 5. CT scan images (axial and coronal sections) demonstrating a dilated appendix, with
adjacent fat stranding, suggestive of acute appendicitis. Arrows, dilated appendix.
APPENDICITIS 125

Fig. 6. CT scan coronal section image demonstrating a dilated appendix, with periappendic-
ular fat stranding and extraluminal gas, suggestive of perforated appendicitis. Arrow, dilated
appendix. Arrowhead, extraluminal gas.

Fig. 7. CT scan axial images demonstrating perforated appendicitis with abscess (left) and
percutaneous CT-guided drainage of the abscess (right). Arrow, abscess. Empty arrow, percu-
taneous catheter insertion.
126 TEIXEIRA & DEMETRIADES

suspicion for appendicitis remains to be determined. For pregnant patients,

however, MRI seems a reasonable alternative to CT scan when ultrasound
is negative or inconclusive [36].
Table 2 highlights a comparison of ultrasound, CT scan, and MRI diag-
nostic capabilities for the diagnosis of acute appendicitis. The appendicitis man-
agement algorithm is described in Fig. 8.

MANAGEMENT ADVANCES AND CONTROVERSIES

Nonoperative management
Nonoperative management is the preferred approach in cases of diagnosis of an
appendiceal mass or abscess [40]. In uncomplicated cases, appendectomy has
been considered the only acceptable therapeutic option. Recent studies have
challenged this concept, however, and support a definitive role of nonoperative
management [41–47]. It has been suggested that the adoption of nonoperative
management for uncomplicated appendicitis is safe and can avoid an operation
in approximately two-thirds of patients [48].
Two recent meta-analyses summarized the findings of prospective random-
ized trials comparing the efficacy of antibiotics versus appendectomy for the
treatment of acute uncomplicated appendicitis [41,47]. According to Mason
and colleagues [47], the nonoperative group had significantly lower risk of
complications at 12% compared with 18% for the appendectomy group
(odds ratio [OR] 0.54; 95% Confidence Interval [CI] 0.37–0.78; P ¼ .001),
which is in agreement with Varadhan and colleagues [41], who demonstrated
a complication risk ratio of 0.69 (95% CI, 0.54–0.89; P ¼ .004) for antibiotics
compared with appendectomy. Appendectomy, however, outperformed the
nonoperative management in terms of overall treatment failure rate. In the anti-
biotic group, the treatment failure rate was 40% compared with 9% in the ap-
pendectomy group (OR 6.72; 95% CI 3.48–12.99; P<.001) [47].
After analysis of similar pooled data sets, both studies agree that antibiotics
are safe as initial treatment of uncomplicated appendicitis, with a significant
decrease in complications but a significant failure rate.
Open versus laparoscopic
Initially described by Semm [49], laparoscopic appendectomy became widely
accepted and currently is the most frequent technique for removal of the appen-
dix (Fig. 9) [50–52]. Although laparoscopy offers several theoretic advantages

Table 2
Comparison of ultrasound, CT scan, and MRI diagnostic capabilities for the diagnosis of acute
appendicitis
Sensitivity Specificity Accuracy PPV NPV
Ultrasound [119] 75%–90% 86%–100% 87%–96% 91%–94% 89%–97%
CT scan [119] 90%–100% 91%–99% 94%–98% 92%–98% 95%–100%
MRI [37,38] 97%–100% 92%–98% 92%–99% 98% 100%
APPENDICITIS 127

Fig. 8. LAC þ USC Medical Center appendicitis management algorithm.

Fig. 9. Trend in the use of laparoscopic technique for appendectomies in California. (Data
from Anderson JE, Bickler SW, Chang DC, et al. Examining a common disease with unknown
etiology: trends in epidemiology and surgical management of appendicitis in California,
1995-2009. World J Surg 2012;36:2787–94.)
128 TEIXEIRA & DEMETRIADES

compared with open procedures, such as less pain, shorter recovery time,
quicker return to work, and decreased inflammatory response, several studies
have failed to demonstrate the superiority of laparoscopic appendectomy.
Studies using the American College of Surgeons National Surgical Quality Improvement
Program (NSQIP) database have consistently demonstrated that laparoscopic
appendectomy is associated with significantly lower incidence of wound infec-
tions compared with open appendectomy. The risk of intra-abdominal abscess
increases, however, if laparoscopy is used [52–54]. Ingraham and colleagues
[52] performed a robust analysis of this large database using propensity score
to minimize the bias associated with the lack of randomization in the study
and found that although laparoscopy was associated with a lower risk of overall
complications, both techniques were comparable in terms of risk of serious com-
plications. Using the same database, other groups found that the laparoscopic
technique was associated with fewer complications in obese patients [55] and
elderly patients [56].
At the Los Angeles County þ University of Southern California (LAC þ
USC) Medical Center, from July 2003 to June 2011, 41% of 4108 appendec-
tomies were performed laparoscopically [57]. Compared with the open proce-
dures, laparoscopic appendectomies were associated with a decreased risk of
wound infection (OR 0.57; 95% CI 0.34–0.97; P ¼ .038).
A recent Cochrane review compiled and analyzed 67 randomized clinical tri-
als comparing laparoscopic with open appendectomy. Laparoscopy was associ-
ated with significantly lower rates of wound infections (OR 0.43; 95% CI 0.34–
0.54) but with a significantly higher incidence of intra-abdominal abscess (OR
1.77; 95% CI 1.14–2.76). The laparoscopic technique was found beneficial for
postoperative pain level, hospital stay, and return to work; however, significant
heterogeneity among the studies included makes the significance of these find-
ings weaker. Although the investigators conclude with a recommendation in
favor of laparoscopic appendectomy, they note that the benefits of laparoscopy
compared with the conventional open technique are small and of questionable
clinical significance [58].
Although laparoscopic technique is associated with a decreased risk of postop-
erative adhesive bowel obstruction compared with most open abdominal opera-
tions, this advantage was not confirmed for appendectomies, as suggested by a
recent systematic review demonstrating no difference in the incidence of this
complication after laparoscopic or open appendectomies (1.4% vs 1.3%) [59].
In summary, approximately 30 years after Semm’s first laparoscopic appen-
dectomy, the surgical community has embraced the technique but the true ad-
vantages compared with conventional surgery remain unclear.

Appendicitis during pregnancy

Appendicitis during pregnancy carries unique diagnostic and management
challenges and can have a negative impact on outcomes for both mother and
fetus. Low birth weight, preterm birth, small for gestational age, low Apgar
scores, and preeclampsia/eclampsia have all been associated with acute
APPENDICITIS 129

appendicitis during pregnancy [60–62]. If perforation develops, fetal mortality

increases from 7% to 10% to as high as 24% [63,64].
A wide spectrum of conditions can present as acute abdominal pain in preg-
nant women and significantly broaden the differential diagnosis. Although the
reported incidence of appendicitis during pregnancy is low, appendicitis is the
most common nonobstetric condition requiring emergent surgery during preg-
nancy [65], occurring during the second trimester in approximately half of
cases [61].
A shift of the anatomic position of the appendix as the uterus size increases,
gestational symptoms, frequent lack of febrile response, and the physiologic
changes of pregnancy, which include leukocytosis, make a diagnosis of acute
appendicitis a dilemma. The diagnostic challenges and the urge to proceed
expeditiously to the operating room may lead to rates of negative explorations
as high as 25% to 50% [10,62,66]. A recent large population-based study iden-
tified that the rate of negative appendectomy in pregnant women is significantly
higher than in nonpregnant women (23% vs 18%; P<.05) [67]. Preoperative
diagnostic accuracy is of utmost importance because a negative surgical explo-
ration is not inconsequential. An overall fetal loss rate of 4% after negative ap-
pendectomy has been reported. Among pregnant women undergoing
appendectomy who sustained a fetal loss or early delivery, almost 1 in 3 had
a negative appendectomy [67].
Ultrasonography is an attractive imaging modality during pregnancy
because of its lack of ionizing radiation, but it is highly operator depended.
When the performance of the study is technically optimal, ultrasonography
has an overall reported sensitivity of 100%, specificity of 96%, and accuracy
of 98% [68]. In instances, however, when obesity or a large uterus limits the
ability to perform graded compression, the ultrasonography findings may be
equivocal. CT scan of the abdomen and pelvis has a reported negative predic-
tive value of 99% for appendicitis [69]. The risk of irradiation to the fetus is of
major concern, however, and most surgeons and emergency physicians use
alternative methods. When presented with the scenario of imaging appendicitis
or abscess in a pregnant patient during the second and third weeks of gestation,
radiologists from 183 academic radiology departments in the United States
chose CT scan over MRI. In patients in the first trimester of pregnancy, how-
ever, the same radiologists were more likely to use MRI [70]. This finding
likely reflects the higher level of concern regarding potential teratogenic effects
of ionizing radiation during the early phase of pregnancy.
It has been suggested that MRI may be a better second-line investigation
compared with CT scan for cases when ultrasonography is equivocal or non-
diagnostic [38,71]. Despite several reports of MRI’s high sensitivity, specificity,
and diagnostic accuracy for acute appendicitis, the exact role of this imaging
modality in assessment of pregnant patients with suspected appendicitis re-
mains unclear [72–75]. Although no report exists of human teratogenic or carci-
nogenic effects of MRI, the safety of MRI for the human fetus has not been
completely proved. The Society for Magnetic Resonance Imaging safety
130 TEIXEIRA & DEMETRIADES

committee has suggested that MRI should be avoided in the first trimester [76].
More recent recommendations from the American College of Radiology state
that MRI is acceptable for pregnant patients at any stage of pregnancy if war-
ranted by the risk/benefit assessment and waiting until the pregnancy is over to
obtain the test is not possible [77].
As nonoperative management emerges as a valid and safe approach to acute
noncomplicated appendicitis, this concept must be applied with caution to preg-
nant patients. This unique population was not included in the studies investi-
gating the safety and efficacy of the nonoperative strategy and extrapolation
of those findings may be problematic [78].
The enlarged uterus may present significant technical challenges for the lapa-
roscopic approach as pregnancy approaches term. The choice of surgical
approach has traditionally been guided by the individual institutional expertise
because both open and laparoscopic techniques have been successfully applied
to appendectomy during pregnancy [79–83]. Experimental work, however,
demonstrated the development of fetal acidemia during pneumoperitoneum us-
ing CO2, with fetal pH falling below 7.20 from its normal 7.33  0.02, with
PCO2 rising above 55 mm Hg [84]. The implications in human fetal physiology
are not fully known. Recent evidence suggests that the laparoscopic technique
may be associated with a significantly higher incidence of fetal loss compared
with open surgery [85]. In that systematic review, including 3415 pregnant
patients undergoing appendectomy, the pooled relative risk of fetal loss for
laparoscopic appendectomy compared with open surgery was 1.91 (95% CI,
1.31–2.77). These data must be interpreted with caution because all the studies
included in the review were observational and no risk adjustment was possible,
which may lead to significant bias. Notwithstanding, an almost 2-fold increase
in fetal loss is worrisome and warrants proper investigation with randomized
trials (Box 2).

TIMING OF OPERATION
Historically, time has been considered an important factor in the management
of acute appendicitis, and emphasis on early diagnosis and immediate surgical
intervention has been an important principle for the successful treatment of this
condition [1,3,5,6,86,87].

Box 2: Appendicitis challenges during pregnancy

Enlarged uterus, gestational symptoms, and physiologic changes of pregnancy
make diagnosis difficult.

Negative appendectomy is associated with significant incidence of fetal loss.

Fetal mortality increases with perforation.

CT scan is potentially harmful to the fetus.

It is unclear if nonoperative management is safe.

Laparoscopic technique may be associated with increased risks for the fetus.
APPENDICITIS 131

Recent studies have suggested that prompt antibiotic followed by a semielec-

tive appendectomy is a safe strategy for the management of appendicitis
[51,88–91]. Those findings are in contrast, however, with several studies
demonstrating a negative impact of appendectomy delay [92–94].
Ingraham and colleagues [51] used the NSQIP database to investigate the ef-
fect of appendectomy delay in outcomes and found that appendectomies per-
formed less than or equal to 6 hours, 6 to 12 hours, and greater than 12
hours after admission had no significant difference in complications. A closer
look at the findings of another group that supported a semielective approach
to appendicitis reveals that the incidence of abscesses requiring drainage
increased from 3% to 6% in patients who were operated on more than 6 hours
after admission [88].
Ditillo and colleagues [93] reviewed 1081 patients undergoing appendectomy
and found that delay to appendectomy had a significant impact both on wors-
ening pathology and on the development of complications, concluding that
delay in appendectomy is unsafe. In another review of 1675 patients undergo-
ing appendectomy for appendicitis, Busch and colleagues [92] found that delay
of 12 hours or more was associated with a significantly higher perforation rate
and longer hospital stay.
More recent data support the negative impact of appendectomy delay.
Over an 8-year period, 4108 appendectomies for acute appendicitis were per-
formed at the LAC þ USC Medical Center. Perforated appendicitis was
found in 23% of the surgical specimens. No deaths occurred; 64% of the pa-
tients underwent appendectomy more than 6 hours after admission, with an
overall average time to appendectomy of 11 hours and 50 minutes, and
58% of the operations were performed during nighttime. Logistic regression
found that appendectomy delay did not increase the risk of perforation.
The independent predictors of perforation identified were age greater than
or equal to 55 years old, white blood cell count greater than 16,000, and
female gender. Fig. 10 demonstrates the incidence of surgical site infections
associated with incremental delay in appendectomy. A delay greater than
6 hours was independently associated with increased incidence of surgical
site infections (adjusted OR 1.54; 95% CI, 1.01–2.34; P ¼ .04) after adjusting
for age, leukocytosis, gender, operative technique (open vs laparoscopic), and
perforation. Particularly significant was a delay in appendectomy for patients
with a nonperforated appendicitis, as demonstrated in Fig. 11. For these pa-
tients, an appendectomy delay greater than 6 hours was associated with an
increase in the incidence of surgical site infections from 1.9% to 3.3% (OR
2.16; 95% CI, 1.03–4.52; P ¼ .03). Early appendectomy (6 hours) for the
group of patients without a perforation was associated with a 42% relative
risk reduction in the development of surgical site infections. Patients who
had their postoperative course complicated with a surgical site infection re-
mained an additional 5 days in the hospital compared with those who did
not have this complication (7.9  5.5 vs 3.4  3.0 days, mean difference
4.5; 95% CI, 3.5–5.5; P<.001 [57].
132 TEIXEIRA & DEMETRIADES

Fig. 10. Incidence of surgical site infections with increasing appendectomy delay. HH:MM,
hours:minutes. (Data from Teixeira PG, Sivrikoz E, Inaba K, et al. Appendectomy timing:
waiting until the next morning increases the risk of surgical site infections. Ann Surg
2012;256(3):538–43.)

Fig. 11. Effect of appendectomy delay in the incidence of surgical site infections, stratified by
perforation presence. TTA, time to appendectomy. (Data from Teixeira PG, Sivrikoz E, Inaba K,
et al. Appendectomy timing: waiting until the next morning increases the risk of surgical site
infections. Ann Surg 2012;256(3):538–43.)
APPENDICITIS 133

In this era of working-hour limitations and tight health care budgets, emer-
gency surgical services face significant challenges to provide care around the
clock. A semielective approach to one of the most frequently performed emer-
gent operation could contribute to optimize hospital resources and personnel
use. The increased morbidity associated with appendectomy delay, however,
suggests that prompt surgical intervention remains the safest approach.

INCIDENTAL APPENDECTOMY
Supporters of incidental appendectomy during elective or emergency surgery
suggest that the risk of adding the appendectomy to the abdominal exploration
being performed for another reason would not significantly increase morbidity
and potentially avoid the need of a future operation for appendicitis. Young pa-
tients, notably those younger than 35 years old, are the age group most likely
to benefit from an incidental appendectomy due to their higher lifetime risk of
developing acute appendicitis [8,95]. The safety of this practice, however, is
questionable. Most studies suggesting that incidental appendectomy is a trivial
procedure with no significant additive morbidity reach that conclusion despite
a lack of proper risk adjustment in their comparisons, which can underestimate
the effect of appendectomy on complications [96–100]. When appropriate scru-
tiny was used to investigate this issue, Wen and colleagues [101] found that an
incidental appendectomy during elective cholecystectomy not only was associ-
ated with increased adjusted risk of morbidity but also had a higher mortality
(OR 2.65; 95% CI, 1.25–5.64; P<.001).
From a cost analysis perspective, incidental appendectomy as a preventive
measure has not been found effective [102] and the high cost of laparoscopic
equipment contributes negatively to the cost-effectiveness equation in the era
of laparoscopic surgery [103].
Controversy exits regarding the function of this otherwise considered vesti-
gial organ. The lymphoid tissue harbored by the appendix is involved in the
production of immunoglobulin IgA, suggesting that this organ may participate
in the localized intestinal immunity [104,105]. Recent evidence also suggests
that appendix may have a role as a reservoir of intestinal commensal bacteria
and contribute with recolonization of the colon with its indigenous bacteria
[106]. This theoretic role of intestinal recolonization may be important in the
recovery after Clostridium difficile infection and may also explain the reported as-
sociation between appendectomy and irritable bowel syndrome [107,108]. The
role of appendectomy and the development and progression of ulcerative colitis
remains controversial [109].
The combination of potential increase in morbidity, cost inefficacy, and lost
of theoretic benefits of preserving the appendix suggest that incidental appen-
dectomy should not be performed except in selected cases.

INTERVAL APPENDECTOMY
The rational for interval appendectomy is the risk of recurrent appendicitis and
possible need for emergent appendectomy. A survey of more than 600 pediatric
134 TEIXEIRA & DEMETRIADES

surgeons in North America found that 86% of the responders routinely perform
interval appendectomy for children initially treated nonoperatively for perfo-
rated appendicitis with phlegmon [110]. Recent data suggest, however, that
the majority of these patients do not have a recurrence of appendicitis. Puapong
and colleagues [111] found a recurrence rate of 8% after a mean follow-up of 8
years, with all recurrences occurring during the first 3 years. The calculated inci-
dence of recurrence was 21% in a recent meta-analysis [112].
Interval appendectomy is not an innocuous procedure. The reported inci-
dence of complications associated with this procedure varies significantly,
ranging from 3% to 18% [112–117]. The indication for this procedure, which
may not be necessary in approximately 80% of patients and has a considerable
risk of complications, has been challenged. It has been proposed that interval
appendectomy is unnecessary [118] and should only be performed if appendi-
citis recurs. The possibility of a malignancy, however, needs to be carefully
excluded in the adult population [114]. Patients older than 40 years with an
appendiceal mass or abscess treated nonoperatively should routinely have a co-
lonoscopy as part of their follow-up because approximately 2% have an alter-
native diagnosis, such as malignancy or Crohn disease, with a majority of
cancer cases occurring in patients over age 40 [40].

SUMMARY
1. Neoplasms are an uncommon finding after appendectomy, with malignant
tumors occurring in less than 1% of the surgical specimens, and carcinoid being
the most frequent malignancy.
2. A negative or inconclusive ultrasound is not adequate to rule out appendicitis and
should be followed by CT scan. For pregnant patients, MRI is a reasonable
alternative to CT scan.
3. Nonoperative treatment with antibiotics is safe as an initial treatment of uncom-
plicated appendicitis, with a significant decrease in complications but a high
failure rate.
4. Open and laparoscopic appendectomies for appendicitis provide similar results
overall, although the laparoscopic technique may be advantageous for obese
and elderly patients but may be associated with a higher incidence of intra-
abdominal abscess.
5. Preoperative diagnostic accuracy is of utmost importance during pregnancy
because a negative appendectomy is associated with a significant incidence of
fetal loss.
6. The increased morbidity associated with appendectomy delay suggests that
prompt surgical intervention remains the safest approach.
7. Routine incidental appendectomy should not be performed except in selected
cases.
8. Interval appendectomy is not indicated because of considerable risks of com-
plications and lack of any clinical benefit.
9. Patients older than 40 years with an appendiceal mass or abscess treated non-
operatively should routinely have a colonoscopy as part of their follow-up to rule
out cancer or alternative diagnosis.
APPENDICITIS 135

References
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