Patient selection: small bowel obstruction
CT findings associated with strangulation in small bowel obstruction (specificity 95 to 100%):
(1) serrated beak configuration of the obstructed bowel loop
(2) poor or no contrast enhancement of the bowel wall
(3) bowel wall thickening
(4) target sign
(5) severe mesenteric vascular engorgement (involving the arcade or root)
(6) severe mesenteric haziness (involving the arcade or root)
Other CT findings associated with strangulation (specificity 80 to 92%):
(1) moderate mesenteric vascular engorgement (involving the arcade)
(2) moderate mesenteric haziness (involving the arcade)
(3) large amount of ascites
(4) abnormal mesenteric vascular course (indicated by one or more of the following: reversal of the superior mesenteric artery and vein, a whirl sign or converging vessels in one area)
While these findings have high specificity, the sensitivity tends to be relatively low.
The presence of 3 or more of these findings was used to make the diagnosis of strangulated bowel, but the diagnosis can be suspected with fewer, especially if these are the high specificity findings.
In cases with equivocal CT findings the clinical findings (see previous section) may help guide the interpretation.
