Findings: A CT of the abdomen with oral contrast only demonstrates free intraperitoneal air, free intraperitoneal fluid, as well as extravasated oral contrast. In addition, a linear tract of air is seen along the medial border of the stomach which is believed to represent the site of perforation.
Diagnosis: Perforated gastric ulcer along the lesser curvature.
Discussion: CT plays no significant role in the initial diagnosis of peptic ulcer disease; however, it is very important in the diagnosis and treatment of complications. Perforation of a peptic ulcer usually results in pneumoperitoneum which is significant enough to be identified on upright or left lateral decubitus plain radiographs of the abdomen. However, sometimes only a very small amount of free intraperitoneal air is present and can only be identified on CT. In this case, a large amount of free intraperitoneal air is seen and presumably would have been recognized on an upright view of the abdomen. The finding of extravasated water soluble oral contrast on this exam is a rare finding.
Ulcers on the anterior wall of the stomach or duodenum directly abut the peritoneal cavity; therefore, perforation of penetrating ulcers of the anterior wall may result in acute peritonitis with spillage of gastric and duodenal contents. The volume of gas that escapes into the peritoneal cavity depends on how quickly the site of perforation becomes sealed off. Pneumoperitoneum is not synonymous with perforated viscous. In fact, pneumoperitoneum is most often a sequela of recent abdominal laparotomy or laparoscopy. Although spontaneous pneumoperitoneum is most often due to perforation of a gastric or duodenal ulcer, other causes include perforation of the remainder of the small bowel or intraperitoneal portions of the colon, extension of pneumomediastinum or pneumothorax.
Ulcers on the posterior wall of the stomach may perforate into the lesser peritoneal cavity or lesser sac. Often a walled-off cavity develops as an inflammatory reaction and fibrous adhesions seal off the perforation site. CT is extremely useful in identifying these fluid collections or abscesses within the lesser sac. In cases of subacute or chronic perforation or in patients who are poor surgical candidates, drainage catheters can also be placed within these abscesses using CT guidance.
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West OC, et al. Abdomen: Nontraumatic Emergencies. In: The Radiology of Emergency
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