Emergency Body CT > Trauma > Bowel (cont.)

Bowel (cont.)

CT inspection for bowel injury must be careful and meticulous because findings can often be subtle. CT signs of bowel and mesenteric injury are varied. Such signs include:

1. Extraluminal air
2. Extravasation of oral contrast
3. Thickened or discontinuous bowel wall
4. A high-attenuation clot (sentinel clot) adjacent to the involved bowel
5. Streaky soft tissue infiltration by fluid

Bowel perforation with massive extravavsation of oral
contrast. The dense contrast filled the peritoneal
cavity tothe right of the falciform ligament (arrow).

While free air in the peritoneal cavity or the retroperitoneum is a relatively specific sign of bowel perforation, it is seen only in 50% of cases. The volume of free air can be quite small and subtle. To optimize visualization of the extraluminal air in comparison to intraluminal air and fat, images should be examined using a wide window setting (i.e., lung windows). It is also important to differentiate intraperitoneal or retroperitoneal air from the extraperitoneal air that may accompany trauma to the thorax.

Retroperitoneal air from duodenal perforation (arrows).


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