Inverted colonic diverticulum: air contrast barium enema findings in six cases.

A polypoid elevation of the colonic wall was identified on air contrast barium enema in six patients. The abnormality in each case was found to be an inverted colonic diverticulum. Inverted diverticula appeared as broad-based, smooth, sessile polyps measuring 1.5-2.0 cm. In five of the six patients a characteristic central umbilication and/or evidence of barium within the polyp could be identified. The diagnosis was confirmed in three patients by demonstrating an everted diverticulum replacing the suspected lesion. In the remaining three patients, two of whom had normal findings on colonoscopy, the diagnosis was strongly suggested by the presence of barium extending into the substance of the mass. Additional radiologic maneuvers or a second study may permit accurate diagnosis if the possibility of inverted diverticulum is considered. However, even when the diverticulum cannot be demonstrated, a central umbilication or barium within a smooth intraluminal projection should suggest inverted diverticulum and prevent unnecessary endoscopy or inadvertent diverticulectomy.