Mistakes in…

Mistakes in CT performed for the acute abdomen and

how to avoid them
Hameed Rafiee and Stuart Taylor

peripancreatic collections to determine their

A
bdominal CT (computed tomography) consistency (fluid versus necrotic tissue), as
is among the most common imaging this can influence management.
tests performed for the investigation of
acute abdominal pathology. There are many
pitfalls that clinicians and radiologists should Mistake 2 Performing a CT scan for acute
be aware of when requesting these studies gastrointestinal bleeding when the
and interpreting the findings. This article patient is clinically stable
covers ten mistakes frequently made with CT scans can be useful for evaluating the cause
abdominal CT, focusing on gastro­intestinal of acute gastrointestinal bleeding, particularly
tract and hepatobiliary pathology. These small and large bowel sources that cannot be
mistakes and their discussions are based on reached via upper gastrointestinal endoscopy.
the available literature where possible and However, CT scans can only detect active bleed-
thereafter on our clinical experience. ing >0.3–0.5 mL/min, and so are best utilised in
patients who are haemodynamically unstable
(but not so unstable that transferring them to
the CT scanner would be dangerous).2 As such,
Mistake 1 CT scanning too early in (CBD) stones can be seen, although, overall, these patients will usually require a medical
patients with acute pancreatitis CT has suboptimal sensitivity for detecting escort to accompany them to the radiology
Acute pancreatitis can usually be diagnosed gallstones. CT scans should be performed after department. Scanning haemodynamically stable
accurately based on clinical features and intravenous contrast administration, ideally patients increases the risk of a false-negative
biochemical markers alone. There is a in dual phases—late arterial (35s) and portal result and should be avoided.
considerable risk that a CT scan performed venous (70s)—to help optimise detection of In addition, the scanning protocol for
within 72 hours of admission will be normal pancreatic necrosis and associated vascular suspected gastrointestinal bleeding must
or underestimate the degree of pancreatic complications. The lower abdomen and pelvis be optimised, using a triple-phase technique
necrosis (Figure 1), so early scanning should should be included to fully assess the extent of (unenhanced, arterial and portal venous
be avoided unless there is a high suspicion of free fluid and collections. phases). The unenhanced scan is used to
severe early complications.1 After 72 hours, MRI (magnetic resonance imaging) is a identify dense luminal contents that may mimic
CT scanning is useful in cases of severe acute viable alternative to CT if available locally, and contrast extravasation on post-contrast images.
pancreatitis to assess the degree of necrosis is more sensitive for identifying mild changes The unenhanced scan is also best placed to
and presence of complications (e.g. pancreatic of pancreatitis. An MRCP (magnetic resonance identify intraluminal blood clots and intramural
duct disruption, pseudoaneurysm formation, cholangiopancreatography) sequence can haemorrhage. The arterial phase is used to
venous thrombosis, fat necrosis, peripancreatic be obtained at the same time to assess for identify the blush of active contrast extravasation
collections and bowel fistulation/ischaemia). pancreatic duct disruption and exclude ductal into the bowel lumen, and the portal venous
Occasionally, obstructing common bile duct gallstones. MRI is also useful for assessing phase helps increase sensitivity by allowing
more time for the extravasation (Figure 2). The
a b portal venous phase also helps differentiate
active bleeding from a pseudo­aneurysm—active
bleeding changes morphology between the

© UEG 2017 Rafiee and Taylor.

Cite this article as: Rafiee H and Taylor S. Mistakes in
acute abdominal CT and how to avoid them. UEG
Education 2017; 17: 18–23.
Hameed Rafiee is at the Norfolk & Norwich
University Hospital, UK. Stuart Taylor is at University
College Hospital, London, UK.
All images courtesy of: H Rafiee and S Taylor.
Figure 1 | CT scans in a patient with acute pancreatitis. a CT scan performed on the day of admission,
Correspondence to: hameed.rafiee@nnuh.nhs.uk
demonstrating a rather fatty pancreatic head with some surrounding fat stranding and free fluid, but no Conflicts of interest: The authors declare there are
evidence of necrosis. b CT scan performed 13 days later, demonstrating extensive necrosis of the pancreatic no conflicts of interest.
head (long arrow) with a significant increase in the volume of peripancreatic fluid causing compression of Published online: May 25, 2017
the superior mesenteric vein (SMV) (short arrow).

18 | 2017 | 17 | UEG EDUCATION www.ueg.eu/education

 Mistakes in…

a b enhancement (in fact, positive oral contrast

is generally not recommended in the setting
of the acute abdomen because of the risk of
missing bowel ischaemia). In some cases, the
CT features are clear cut (i.e. mural oedema,
poor mural enhancement, intramural gas, free
fluid and associated vascular filling defects +/-
the presence of gas in the portal system).
The features present can differ depending
on the cause—venous occlusion tends to cause
more mural oedema and mesenteric conges-
c tion than arterial occlusion, whereas arterial
occlusion tends to reduce mural enhancement
earlier and also causes earlier transmural
infarction.4 The mesenteric arteries and veins
should always be carefully assessed for the
presence of filling defects representing an
embolus (in arteries) or a thrombus (in veins or
arteries). In the mesenteric arteries, thrombosis
usually occurs near the origin of the superior
mesenteric artery (SMA)/inferior mesenteric
Figure 2 | Active bleeding in a patient with a transverse colon diverticulum. a Arterial phase CT showing artery (IMA), whereas emboli tend to wedge
active bleeding arising from a transverse colon diverticulum. b Arterial phase CT showing the jet of active at branching points.5 Occasionally in cases of
contrast extravasation extending proximally within the transverse colon. c Portal venous phase CT arterial embolism, small infarcts may be seen in
demonstrating a marked increase in size of the contrast blush within the transverse colon, in keeping with the spleen or kidneys, and in rare instances
brisk active bleeding.
a thrombus may be visible in the left
atrial appendage acting as a source for the
arterial and portal venous phases, whereas a that there is a transition point at the stoma site. emboli.
pseudoaneurysm retains its shape and changes A substantial volume of free intraperitoneal Venous thrombosis has many different
only in density. Once the bleeding site has been gas can persist in the first 2–3 postoperative causes, such as thrombophilia, myeloprolif-
identified, a careful review of the area is needed days, making assessment of anastomotic erative disorders, malignancy, inflammation,
to look for the underlying cause (e.g. a tumour, leaks difficult. Postoperative collections are recent surgery/trauma, portal hypertension
ulceration, diverticula, ischaemia, inflammation, best assessed after day 7, by which time and oral contraceptives6. It is not uncommon
varices, arterioenteric fistula, angiodysplasia or normal postoperative fluid should have been to see typical features of ischaemia without
other vascular malformations). reabsorbed and any infected collections a visible arterial/venous occlusion—in
encapsulated. Before encapsulation has these cases the differential diagnosis also
occurred, it can be difficult to distinguish a includes vasculitis (e.g. polyarteritis nodosa,
Mistake 3 CT scanning too early after normal pocket of free fluid from an infected Henoch–Schönlein purpura, systemic lupus
bowel surgery collection. Care should also be taken not to erythematosus and Behçet syndrome), over-
Postoperative complications, such as bowel mistake absorbable haemostatic packing distension of the bowel (e.g. due to bowel
obstruction and anastomotic leaks, are material (used intraoperatively to stop bleed- obstruction, faecal impaction or paralytic ileus)
common. CT is usually the investigation of ing) for an abscess, as these can often be and low-flow states (e.g. hypovolaemic shock,
choice; however, interpreting scans from the indistinguishable on imaging (figure 3)—the
immediate postoperative period is difficult. surgical team should be consulted if there is
Paralytic ileus can mimic small bowel any doubt.
obstruction in the first 48 hours,3 particularly in
the presence of an ileostomy as it may appear
Mistake 4 Not recognising ischaemic bowel
Bowel ischaemia is often fatal if unrecognised,
and can be a difficult clinical diagnosis to
make. When assessing this on CT it is vital to
give IV contrast to assess vascular patency and
bowel wall enhancement—both arterial and
portal venous phases are recommended.
A pre-contrast scan may help to identify
Figure 4 | Colonic ischaemia due to sacrifice of the
inferior mesentericcartery during open abdominal
intramural haemorrhage, which can mimic
mural enhancement on post-contrast images aortic aneurysm repair. The advanced ischaemia in
alone, but is not always necessary as other the descending colon (long arrow) demonstrates
Figure 3 | Absorbable haemostatic packing material post-contrast features will usually indicate poor transmural enhancement. By contrast, the less
in the gallbladder fossa post cholecystectomy, the diagnosis. It is also important not to give severe ischaemia in the transverse colon (short
c
mimicking an abscess. positive oral contrast, as this will mask mucosal arrow) demonstrates mucosal hyperenhancement.

www.ueg.eu/education UEG EDUCATION | 2017 | 17 | 19

 Mistakes in…
heart failure or drug-induced splanchnic
a
vasoconstriction). Ischaemia due to low-flow
states usually occurs at watershed areas
between vascular territories (e.g. at the splenic
flexure, at the rectosigmoid junction and,
rarely, in the caecum).
In some cases of bowel ischaemia the CT
features are subtle—bowel dilatation without
a discrete transition point can occasionally be
the only sign of ischaemia. Furthermore, there
may be paradoxical hyperenhancement of the
c
bowel wall rather than reduced enhancement
(Figure 4), due to hyperaemia and/or
reperfusion via collaterals. Intramural and
portal system gas are ominous signs in the
presence of bowel ischaemia, indicating
transmural infarction; however, intramural b
gas does not always imply ischaemia and
is also seen in benign pneumatosis. In
these cases, the patients will usually be
asymptomatic and other features of
ischaemia will be absent.

Mistake 5 Not recognising a closed loop

small bowel obstruction
CT is the imaging test of choice when
investigating small bowel obstruction. One
of the most important considerations is Figure 5 | Closed loop small bowel obstruction. a Formation of a closed loop small bowel obstruction most
whether a closed loop obstruction is present often occurs when an adhesive band has crossed over a loop of bowel, obstructing the afferent and efferent
(i.e. two transition points at a single location limbs, but can also occur as a result of a volvulus, which is the twisting of a loop of intestine around itself.
creating a bowel loop that is obstructed at both b Closed loop small bowel obstruction with venous ischaemia of the closed loop (long arrow) demonstrating
ends [figure 5a]). In most cases an adhesive mural and mesenteric oedema, reduced mural enhancement and free fluid. Note the visible adhesive band
band (usually related to previous surgery) traversing the small bowel (short arrow) due to entrapment of fat within the band. c | High-grade closed
loop small bowel obstruction with two adjacent transition points (long arrow) and no appreciable mural
has crossed over a loop of bowel, thereby
enhancement within the closed loop. There is a little intramural gas within the closed loop (short arrow) in
obstructing the afferent and efferent limbs keeping with infarction.
(figure 5b). However, volvulus and hernias
(both external and internal) may also be
responsible. Closed loop obstruction requires obliteration of mesenteric veins as they pass
urgent surgical intervention because of the risk through the point of obstruction followed Mistake 6 Not recognising mimics of
of strangulation at the point of obstruction, by venous engorgement within the closed Crohn’s disease
causing mesenteric venous occlusion and loop mesentery, a cluster of stacked Patients with Crohn’s disease often present
subsequent venous ischaemia and infarction oedematous bowel loops, and a ‘whirl’ sign with an acute abdomen, and distinguish-
(Figure 5c). When features of venous within the mesentery as it approaches the ing active Crohn’s disease from its mimics is
ischaemia are present, it is usually straight­ point of obstruction. The ‘whirl’ sign can be important as the treatment for active Crohn’s
forward to diagnose closed loop obstruction seen in any cause of closed loop obstruction, disease (i.e. steroids and other immuno­
on CT, as the oedematous dilated bowel and but is particularly prominent in cases of vol- suppressants) can exacerbate the other
congested mesentery stand out from the rest of vulus. Patients with small bowel volvulus also conditions. The terminal ileum is the most
the dilated thin-walled bowel. usually have a predisposing congenital frequent site of inflammation in active Crohn’s
In cases secondary to band adhesions, the intestinal malrotation. disease and is represented on CT by mural
point of obstruction can be difficult to identify, as Internal hernias are a rare cause of closed thickening and enhancement, +/- stricturing,
the adhesions are not usually visible (except in loop obstruction and occur through peritoneal +/- an adjacent inflammatory phlegmon or
rare cases where a little fat becomes entrapped defects, foramina and recesses (e.g. foramen abscess and +/- fistulation with adjacent bowel
within the band [figure 5b]). The small bowel of Winslow, paraduodenal/pericaecal fossae, loops or the bladder. However, terminal ileal
faeces sign (semisolid content in the small perirectal/supravesical recesses, and thickening can also be seen in other acute
bowel lumen), if present, can help to identify transomental/transmesenteric/broad conditions, most commonly acute appendicitis,
the point of obstruction. The cardinal signs ligament defects), which may be congenital for which there may be secondary oedema of
of closed loop obstruction include two tightly or acquired (e.g. the Petersen’s defect in the terminal ileum and an appendix abscess
angulated bowel loops in close proximity the transverse mesocolon in patients mimicking a Crohn’s abscess (figure 6).
with beaked tapering and convergence at who have had a retrocolic roux-en-Y A careful review is required to locate the
the point of obstruction, focal narrowing/ anastomosis). appendix and assess it for any signs of

20 | 2017 | 17 | UEG EDUCATION www.ueg.eu/education

 Mistakes in…
disease should include radiation enteritis a
(usually involving pelvic small bowel loops)
and NSAID (nonsteroidal anti-inflammatory
*
drug) enteropathy (usually causing very short
shelf-like strictures). Less frequent mimics of
Crohn’s disease also include lymphoma,
eosinophilic gastroenteritis, sarcoidosis,
amyloidosis, systemic mastocytosis and
endometriosis.8

Figure 6 | Mimics of Crohn’s disease. Acute

appendicitis (long arrow) with a small abscess Mistake 7 Missing small bowel diverticulosis
(star) and mild reactive thickening of the terminal Small bowel diverticula are often missed on CT b
ileum (short arrow).
scans because they can be difficult to pick out
from the rest of the small bowel, particularly in
inflammation. In some cases, the appendix is thin patients in whom the small bowel is tightly
engulfed or obliterated by the abscess and packed. Diverticula can cause various symptoms
is not identifiable, making it more difficult via diverticulitis, perforation (figure 7),
to differentiate appendicitis from Crohn’s enterolith formation (with resultant small bowel
disease. Assessment of the rest of the small obstruction), intussusception, gastrointestinal
and large bowel can help to identify skip bleeding, or malabsorption due to bacterial
lesions distant from the inflammation in the overgrowth. Identifying the presence of small
right iliac fossa that would point towards a bowel diverticula aids accurate diagnosis and
diagnosis of Crohn’s disease. appropriate management, which is particularly Figure 7 | Small bowel diverticula. a An axial image
Another important mimic of Crohn’s disease important in those patients presenting acutely. showing several small bowel diverticula, one of
is tuberculosis, which in the gastrointestinal Small bowel diverticula occur more frequently which (long arrow) is thick walled with surrounding
tract most often involves the ileocaecal region. It and are larger in the jejunum than the ileum. fat stranding in keeping with inflammation. b | A
can be difficult to differentiate the two on CT, but They are usually found on the mesenteric coronal image of the same patient demonstrating a
there are certain helpful differentiating features. border where the mesenteric vessels penetrate bubble of free gas (short arrow) related to the
Tuberculosis affects the caecum much more the bowel wall, causing a focal weakness in inflamed jejunal diverticulum seen on the axial
image. The cause of the perforation was an ingested
commonly than Crohn’s disease,7 often the muscularis propria, allowing mucosa
bone (long arrow) that had migrated more distally
causing contraction and fibrosis, giving the and submucosa to herniate through. within the bowel by the time of the CT.
caecum a conical appearance. The presence Careful assessment of CT scans in the axial,
of large centrally hypoattenuating (necrotic) coronal and sagittal planes usually allows
mesenteric lymph nodes, peritoneal thickening/ identification of diverticula. Another helpful can help improve sensitivity by distending the
nodularity and significant ascites also point feature of diverticula is the absence of valvulae small bowel loops with fluid and making them
towards tuberculosis. conniventes, aiding differentiation from normal easier to follow, and should be considered if
Other infections that affect the ileocaecal small bowel loops. there is a high clinical suspicion for a Meckel’s
region include those caused by Yersinia, Another type of small bowel diverticulum is diverticulum. A Technetium-99m pertechnetate
Salmonella and Campylobacter species, but they a Meckel’s diverticulum, a congenital scan can detect diverticula containing ectopic
are usually easy to differentiate from Crohn’s malformation caused by embryological failure gastric mucosa, but has a limited sensitivity
disease based on clinical features and a stool to obliterate the omphalomesenteric duct. of 60%.9
sample. On CT imaging, they cause thickening/ A Meckel’s diverticulum arises from the
oedema of the bowel wall without skip lesions, antimesenteric border of the distal ileum and
fistulation or phlegmon/abscess formation. In is said to follow the ‘rule of twos’—2% of Mistake 8 Mistaking a perforated colonic
immunocompromised patients, neutropenic the population, 2 inches long, 2 feet from carcinoma for perforated diverticulitis
colitis and CMV enterocolitis should also be the ileocaecal valve, 2/3 contain ectopic Colonic diverticulitis and carcinoma can both
considered, although both of these more mucosa (usually gastric), and 2% become cause perforation of the bowel, and can be
commonly involve the colon rather than the symptomatic (most often in males). The most difficult to differentiate on CT—they both
small bowel. Anisakiasis and histoplasmosis frequent symptom is gastrointestinal bleeding, present as thick-walled strictures and the
can mimic Crohn’s disease on imaging, albeit although inflammation, perforation and presence of perforation inevitably creates
rarely, but careful history taking will usually small bowel obstruction (due to adhesions, surrounding fat stranding in either case.
differentiate them. Actinomycosis is a rare enterolith formation, volvulus, intussusception Obtaining an endoscopic diagnosis can also
infection that can involve the bowel, and or internal hernia related to a persistent be difficult, particularly if the stricture is
causes infiltrative enhancing soft tissue masses omphalomesenteric duct) can also occur. In impassable with a scope. There are, however, a
that extend readily through soft tissue planes. patients who have acute complications, a few CT features that can help differentiate
The appearance may mimic an inflammatory Meckel’s diverticulum is usually easy to the two (figure 8).
phlegmon, but there is usually no significant identify, but in outpatients who have more Malignant strictures tend to be shorter
bowel wall oedema and no ascites. chronic symptoms (e.g. intermittent gastro- than diverticular strictures and usually have
In patients with multifocal small bowel intestinal bleeding), a Meckel’s diverticulum shouldered margins with straightening
strictures, considerations other than Crohn’s can be difficult to see on CT. CT enterography of the thick-walled segment.10 The mesenteric

www.ueg.eu/education UEG EDUCATION | 2017 | 17 | 21

 Mistakes in…
This can be mistaken for colitis with adjacent conservative management, so it is important to
fat stranding because the colon adjacent to recognise them to avoid unnecessary invasive
the inflamed omentum may be secondarily procedures.
* inflamed/oedematous, but a careful assessment
usually reveals that the bowel wall thickening
and adjacent fat stranding is too eccentric to Mistake 10 Missing gallstones
represent colitis (figure 9b). Sometimes the Ultrasound is the primary imaging modality
inflamed omentum may appear somewhat for assessing gallbladder and biliary pathology,
mass-like and mimic a liposarcoma or an and is much more reliable than CT for
Figure 8 | Colon carcinoma versus diverticular omental cake, but it is usually possible to identifying gallstones. Ductal calculi can,
stricture. A sigmoid tumour (long arrow) differentiate these on CT—if there is any doubt, however, be difficult to see on ultrasound due
demonstrating irregular mural thickening, loss of
follow up will demonstrate involution of the to overlying bowel gas, and will often require
mural stratification, straightening of the bowel loop
and focal areas of low attenuation and calcification omental infarct. Omental flaps used in surgical cross-sectional imaging to diagnose—usually
due to mucin content. A markedly enlarged procedures (e.g. abdominoperineal resection) MRCP because it is much more sensitive than
mesenteric node is also seen (star). Just upstream of may also undergo infarction and mimic local CT. Occasionally, however, gallstones can be
the tumour is a segment of diverticular disease tumour recurrence, but awareness of this picked up on CT scans performed in cases for
(short arrow) demonstrating milder mural phenomenon helps avoid this pitfall. which the diagnosis is uncertain (e.g. in cases
thickening with preservation of mural stratification Epiploic appendagitis (infarction of an of acute pancreatitis) or incidentally on CT
and small gas-filled diverticula within the thickened
segment. epiploic appendage of the colon due to torsion scans performed for other reasons.
or occlusion of its central vessel), presents as a Approximately 80% of gallstones are
small (<5 cm) halo of fat stranding, sometimes visible on CT.12 Some are calcified, others
lymph nodes are also often larger and may containing a central dot, adjacent to the colon may contain gas, but many gallstones are only
contain hypoattenuating foci (representing anywhere from the caecum to the rectosigmoid visible due to a subtle ring of increased density
mucin or necrosis), which are highly junction (figure 9c). This usually has a charac- in their periphery (figure 10). In patients who
suggestive of malignancy. Malignant strictures teristic appearance but may be quite subtle, have acute pancreatitis or unexplained biliary
are also more likely to cause large bowel and the adjacent colon is not usually inflamed. dilatation on CT, the CBD must be inspected
obstruction. Diverticular strictures tend to be Encapsulated fat necrosis is an unusual carefully, because if these subtle calculi are
longer, with tapered margins and preservation entity that can occur anywhere in the body and identifiable on CT it avoids the need for MRCP.
of the normal colonic curvature. The presence is thought to be related to trauma. It presents An unenhanced CT can be helpful to increase
of gas-filled diverticula within the thick-walled as a well-defined encapsulated fatty mass, the conspicuity of gallstones. Patients who
segment is suggestive of a diverticular stricture sometimes containing a fat-fluid level, which present with recurrent abdominal pain after
rather than malignancy. Preservation of may demonstrate a little capsular enhance- cholecystectomy may undergo CT to exclude
stratified mural enhancement within the ment. Such necrosis can mimic a liposarcoma, postoperative collections. As well as look-
thickened colon is also suggestive of benign but follow-up imaging will demonstrate ing carefully for retained ductal stones, the
inflammation, whereas tumours usually involution rather than progression. Most forms abdominal cavity (particularly the perihepatic
demonstrate more homogenous enhance- of fat necrosis are self limiting and resolve with space) should be assessed for any rounded
ment (except for mucinous tumours, which
can appear heterogeneously hypovascular).
In many cases, however, it is difficult to be a c
definitive and repeat endoscopy or follow-up
imaging may be required to exclude an under-
lying tumour (if the patient does not undergo
surgery for the perforation).

Mistake 9 Not recognising fat necrosis

Fat necrosis can occur in several settings and be
mistaken for other pathologies on CT. In patients
with acute pancreatitis there may be extensive
fat necrosis throughout the mesenteric and
retroperitoneal fat that can appear quite b Figure 9 | Fat necrosis. a Extensive nodular fat
nodular (figure 9a), mimicking disseminated necrosis involving the omentum, mesentery and
malignancy.11. Fat necrosis will involute on retroperitoneal fat in a patient with acute
subsequent CT scans in the following days to pancreatitis; the necrosis slowly resolved on
subsequent CT scans. b | A large focal area of fat
weeks, unlike malignancy which will progress.
stranding within the greater omentum in keeping
Omental infarction presents as a swollen with omental infarction. Note the associated
encapsulated fatty mass (usually >5 cm) eccentric mural thickening of the adjacent
containing fat stranding that overlies the bowel transverse colon–this must not be mistaken for
loops, often adjacent to the ascending colon colitis. c A small focal area of fat stranding adjacent
since the right lateral margin of the greater to the distal descending colon in keeping with
omentum has the weakest blood supply. epiploic appendagitis.

22 | 2017 | 17 | UEG EDUCATION www.ueg.eu/education

 Mistakes in…
tree.13 Recognising dropped gallstones is crucial 6. Duran R, et al. Multidetector CT features of
a mesenteric vein thrombosis. Radiographics 2012; 32:
because the definitive treatment is
1503–1522.
usually surgery rather than percutaneous 7. Sharma R, et al. Intestinal tuberculosis versus Crohn’s
drainage. disease: clinical and radiological recommendations.
Indian J Radiol Imaging 2016; 26: 161–172.
References 8. DiLauro S and Crum-Cianflone NF. Ileitis: when it is
1. Busireddy KK, et al. Pancreatitis—imaging approach. not Crohn’s disease. Curr Gastroenterol Rep 2010;
World J Gastrointest Pathophysiol 2014; 5: 252–270. 12: 249–258.
2. Artigas JM, et al. Multidetector CT angiography for 9. Elsayes KM, et al. Imaging manifestations of
acute gastrointestinal bleeding: technique and Meckel’s diverticulum. AJR 2007; 189: 81–88.
findings. Radiographics 2013; 33: 1453–1470. 10. Lips LMJ, et al. Sigmoid cancer versus chronic
3. Weinstein S, et al. Multidetector CT of the postoperative diverticular disease: differentiating features at CT
colon: review of normal appearances and common colonography. Radiology 2015; 275: 127–135.
complications. Radiographics 2013; 33: 515–532. 11. Kamaya A, et al. Imaging manifestations of
4. Moschetta M, et al. Multi-detector CT features abdominal fat necrosis and its mimics. Radiographics
of acute intestinal ischemia and their 2011; 31: 2021–2034.
prognostic correlations. World J Radiol 2014; 12. Barakos JA, et al. Cholelithiasis: evaluation with CT.
b 6: 130–138. Radiology 1987; 162: 415–418.
5. Furukawa A, et al. CT diagnosis of acute mesenteric 13. Ramamurthy NK, et al. Out of sight but kept in mind:
ischaemia from various causes. AJR 2009; complications and imitations of dropped gallstones.
192: 408–416. AJR 2013; 200: 1244–1253.

Your imaging the acute abdomen briefing

• “Role of imaging in the diagnosis of IBD” Presentation
UEG Week at UEG Week 2013
Figure 10 | A subtle gallstone. a Subtle gallstone in • “MRI and CT: What’s new?” Presentation at UEG Week [https://www.ueg.eu/education/document/
the distal common bile duct (CBD) with a rim of 2016 [https://www.ueg.eu/education/document/ role-of-imaging-in-the-diagnosis-of-ibd/104103/].
slightly increased attenuation. b | Coronal image of mri-and-ct-what-s-new/131292/].
Standards and Guidelines
the same patient demonstrating the subtle distal • “MRI” Presentation at UEG Week 2016 • Taylor S, et al. The first joint ESGAR/ ESPR consensus
[https://www.ueg.eu/education/document/
CBD stone. statement on the technical performance of
mri/129067/].
cross-sectional small bowel and colonic imaging. Eur
• “Acute abdomen in the elderly” Presentation at UEG Radiol Epub ahead of print 18 Oct 2016. DOI: 10.1007/
lesions that could represent dropped Week 2015 [https://www.ueg.eu/education/document/ s00330-016-4615-9.
gallstones, as these are a recognised cause of acute-abdomen-in-the-elderly/116539/]. [https://www.ueg.eu/education/document/
post-cholecystectomy pain and can act as a • “Imaging of the acute abdomen” Presentation at UEG the-first-joint-esgar-espr-consensus-statement-on-
Week 2014 [https://www.ueg.eu/education/document/ the-technical-performance-of-cross-sectional-small-
nidus for recurrent abscess formation, some- imaging-of-the-acute-abdomen/108823/]. bowel-and-colonic-imaging/144431/]
times many years after the cholecystectomy. • “The role of imaging in acute pancreatitis” • Further relevant articles can be found by
Occasionally, dropped gallstones can migrate Presentation at UEG Week 2014 navigating to the ‘Radiology and imaging’ category
into unusual places such as the retroperito- [https://www.ueg.eu/education/document/ in the “Standards & Guidelines’ repository.
the-role-of-imaging-in-acute-pancreatitis-ce- [https://www.ueg.eu/education/standards-guidelines/]
neum, abdominal wall, intestine, genitourinary ct/109381/].
tract, pleural cavity and even the bronchial

www.ueg.eu/education UEG EDUCATION | 2017 | 17 | 23