Gastrointestinal perforation CT
[{CMG}}; Associate Editor(s)-in-Chief: Mohammed Abdelwahed M.D[1]
Overview
Chest CT
Pneumothorax, pneumomediastinum, pleural effusion, mediastinal abscess.
Abdominal CT
Signs of perforation on abdominal CT scanning include extraluminal air (image 6); extraluminal oral contrast; free fluid or food collections; and discontinuity of the intestinal wall, fistula, or intra-abdominal abscess often associated with irregular adjacent bowel wall thickening [82,93,99,100].
CT
The role of CT is usually to look for stigmata of perforation when fluoroscopy is equivocal, and there is persisting suspicion of perforation. These include
extraluminal gas locules in the mediastinum or abdominal cavity, adjacent to the esophagus are highly suggestive 2, 4
pleural or mediastinal fluid
pneumomediastinum or pneumothorax
pericardial or pleural effusions can be seen Water soluble oral contrast can be administered 20 minutes before scanning to demonstrate extravasation. Intravenous contrast is usually administered to delineate the oesophageal wall (25 - 60-second delay) 8.
CT
this is the primary imaging modality for detection and localization of bowel perforation
the site of the perforation can often be localized by:
tracking the bubbles of pneumoperitoneum toward a region of the bowel
looking for localized peritoneal fat stranding or bowel wall thickening o determining a site of bowel wall discontinuity
if the patient received oral contrast, then often the leak can be seen directly as contrast spills out of the perforation site
if a suspected bowel perforation is the primary indication for the study, then protocolling the study with a water-soluble contrast medium is useful
if a bowel perforation occurs due to obstruction, the perforation usually occurs at the site of maximal bowel distention and the perforation may be distant from the actual cause of the bowel obstruction
a bowel perforation may not result in pneumoperitoneum, but liquid contents exiting the bowel may form a phlegmon or abscess