Imaging of Acute Small-Bowel Obstruction
Savvas Nicolaou1,
Brian Kai2,
Stephen Ho3,
Jenny Su4 and
Karim Ahamed5
1 Department of Radiology, Vancouver General Hospital, 899 W 12th Ave.,
Vancouver, BC, V5Z 1M9, Canada.
2 University of British Columbia, Vancouver, BC, Canada.
3 Department of Radiology, Gastrointestinal Radiology, Vancouver Hospital &
Health Sciences Centre, Vancouver, BC, Canada.
4 Department of Internal Medicine, University of British Columbia, Vancouver,
BC, Canada.
5 Department of Diagnostic Radiology, University of Alberta, Edmonton, AB,
Canada.
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Fig. 1A —Small-bowel obstruction on radiography. Supine abdominal
radiograph in 45-year-old woman with adhesional small-bowel obstruction shows
multiple dilated loops of small bowel. Valvulae conniventes appear prominent.
In appropriate clinical context, this would be diagnostic of small-bowel
obstruction.
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Fig. 1B —Small-bowel obstruction on radiography. Upright abdominal
radiograph in 56-year-old woman with adhesional small-bowel obstruction shows
multiple air-fluid levels (arrows) and string-of-pearls sign
(arrowhead).
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Fig. 2A —48-year-old woman presenting with gallstone ileus. Upright
abdominal radiograph shows multiple air-fluid levels. Pneumobilia
(arrow) is present, as is string-of-pearls sign
(arrowheads).
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Fig. 2B —48-year-old woman presenting with gallstone ileus. CT scan
through upper abdomen shows air in gallbladder (arrow) and proximal
cystic duct.
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Fig. 2C —48-year-old woman presenting with gallstone ileus. CT scan
obtained inferior to B shows calcified impacted gallstone
(arrow) in distal jejunum with proximal dilated loops of bowel.
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Fig. 3A —Strangulation. Supine abdominal radiograph in 46-year-old
woman with ischemic colitis shows linear radiolucency (arrows) along
wall of bowel, which is consistent with pneumatosis intestinalis. Dilated
loops of small bowel are also present.
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Fig. 3B —Strangulation. Right-side-up decubitus abdominal radiograph
in 69-year-old woman shows multiple branching radiolucencies (arrows)
in periphery of liver shadow, which is indicative of portal venous gas.
Dilated loops of small bowel are also present, which is consistent with
small-bowel obstruction.
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Fig. 4 —Enteroclysis. 54-year-old woman with adhesional small-bowel
obstruction. Spot film from enteroclysis shows small-bowel loop narrowing
(arrow) due to postoperative adhesion.
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Fig. 5A —Sonography features of small-bowel obstruction. Both cases
are due to postoperative adhesions. Abdominal sonogram in 40-year-old woman
shows dilated, fluid-filled loop of small bowel with prominent valvulae
conniventes (arrows).
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Fig. 5B —Sonography features of small-bowel obstruction. Both cases
are due to postoperative adhesions. Abdominal sonogram in 62-year-old man
shows thickened small-bowel wall (arrows). Real-time scanning showed
small bowel to be hyperperistaltic.
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Fig. 6A —Small-bowel obstruction secondary to adhesions. Axial CT scan
through lower abdomen in 54-year-old woman with small-bowel obstruction
secondary to adhesions shows multiple fluid-filled loops of small bowel
(arrows).
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Fig. 6B —Small-bowel obstruction secondary to adhesions. CT scan
obtained inferior to A shows transition point (arrows) with
dilated bowel proximally and collapsed bowel distally. No pathologic process
is visualized at transition point, and transition is smooth. This obstruction
was found to be adhesional in nature.
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Fig. 6C —Small-bowel obstruction secondary to adhesions. Axial
contrast-enhanced CT scan through mid abdomen of 55-year-old man with
small-bowel obstruction secondary to adhesions shows multiple fluid-filled
loops with tapering transition point (arrows), otherwise known as
beak sign.
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Fig. 7A —Small-bowel obstruction secondary to Crohn's disease. Axial
CT scan through lower abdomen of 44-year-old woman with small-bowel
obstruction secondary to Crohn's disease shows multiple fluid-filled loops of
small bowel (arrows) and CT equivalent of string-of-pearls sign on
radiography.
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Fig. 7B —Small-bowel obstruction secondary to Crohn's disease. Axial
CT scan through lower abdomen in 28-year-old woman with Crohn's disease shows
partially solid material intermixed with air within distal small bowel
(arrows), similar in appearance to feces in colon; this finding is
called the "small-bowel feces" sign.
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Fig. 8A —58-year-old woman with small-bowel obstruction secondary to
adhesions. Axial CT scan through lower abdomen shows dilated proximal loop
(arrow) and collapsed distal loop (arrowhead).
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Fig. 8B —58-year-old woman with small-bowel obstruction secondary to
adhesions. CT scan obtained inferior to A shows narrowing of involved
loop of bowel (arrows). Adhesion is inferred to be causing narrowing
given history of previous abdominal surgery and given neither masses nor
extrinsic processes are seen to result in narrowing. Multiple dilated loops of
small bowel are also seen.
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Fig. 9 —26-year-old woman with vasculitis and small-bowel
obstruction. Axial contrast-enhanced CT scan through mid abdomen shows
thickened loops of small bowel and target sign (arrows). Free fluid
(arrowhead) is also seen.
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Fig. 10A —66-year-old woman with diagnosis of ischemic bowel. Axial
contrast-enhanced CT scan through mid abdomen shows multiple dilated air- and
fluid-filled loops of small bowel. There is evidence of pneumatosis
intestinalis and lack of bowel wall enhancement (thin arrow) as
compared with normally enhancing loop (thick arrow). Also seen is
intraperitoneal free fluid (arrowhead). Round radiodensity seen in
one loop of small bowel is surgical drain.
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Fig. 10B —66-year-old woman with diagnosis of ischemic bowel. CT scan
obtained inferior to A shows air in mesentery (arrowhead), and
lack of bowel wall enhancement (arrows) is again seen.
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Fig. 10C —66-year-old woman with diagnosis of ischemic bowel. CT scan
obtained superior to A shows air in intrahepatic portal venous
vasculature (arrow).
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Fig. 12A —64-year-old man with small-bowel obstruction secondary to
incarcerated right inguinal hernia. CT scan shows incarcerated right inguinal
hernia resulting in small-bowel obstruction. Left and right arrows point to
dilated loop of small bowel with engorged mesentery (middle
arrow).
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Fig. 12B —64-year-old man with small-bowel obstruction secondary to
incarcerated right inguinal hernia. Inferior transverse CT image obtained at
level of symphysis pubis reveals incarcerated thick wall loop of small bowel
within right inguinal canal (arrow).
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Fig. 13 —80-year-old man with small-bowel obstruction secondary to
adenocarcinoma of large bowel. Coronal reformatted 2-mm-thick CT view of
abdomen reveals small-bowel obstruction is caused by thick annular
constricting mass lesion involving hepatic flexure of large colon (thin
arrows) resulting in proximal dilatation of cecum (thick arrow)
and small bowel (arrowheads). Pathology revealed colonic
adenocarcinoma.
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Fig. 14A —49-year-old man with incarcerated abdominal hernia. Axial CT
scan shows defect in lower abdominal wall (arrow) that has
incarcerated lower abdominal hernia within it (arrowhead).
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Fig. 14B —49-year-old man with incarcerated abdominal hernia. Sagittal
reformatted MDCT view depicts defect in lower abdominal wall (long thick
arrow) and incarcerated lower abdominal hernia. Within hernia sac, thick
wall loop of small bowel and free fluid (arrowhead) are noted with
dilated loops of small bowel proximal (short thick arrow) to
incarcerated small-bowel loop. Free fluid (star and thin
arrow) is also present in abdomen, which is an associated finding in
small-bowel obstruction.
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Fig. 15A —80-year-old man with small-bowel obstruction secondary to
adenocarcinoma of large bowel. Transverse gadolinium-enhanced T1-weighted
image (TR/TE, 400/10) obtained with fat saturation shows narrowing of large
bowel (arrow) caused by mass (small arrowhead) with
resultant proximal small-bowel obstruction (large arrowhead).
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Fig. 15B —80-year-old man with small-bowel obstruction secondary to
adenocarcinoma of large bowel. Coronal single-shot fast spin-echo T2-weighted
image (1,800/103) reveals same constricting mass seen in A but with
intermediate signal (thin arrows). Resultant proximal dilatation of
large (thick arrow) and small (arrowheads) bowel is
visualized.
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Fig. 15C —80-year-old man with small-bowel obstruction secondary to
adenocarcinoma of large bowel. Subsequent coronal image reveals numerous
proximal dilated loops of small bowel (arrows), which is consistent
with diagnosis of small-bowel obstruction.
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Copyright © 2005 by the American Roentgen Ray Society.
or 
shape. If
orientation of loop is at right angle to axial plane, appearance will vary
depending on slice.