Colonic perforation by a transmural and transvalvular migrated retained sponge: multi-detector computed tomography findings.

Transmural migrated retained sponges usually impact at the level of the ileo-cecal valve leading to a small bowel obstruction. Once passed through the ileo-cecal valve, a retained sponge can be propelled forward by peristaltic activity and eliminated with feces. We report the case of a 52-year-old female with a past surgical history and recurrent episodes of abdominal pain and constipation. On physical examination, a generalized resistance was observed with tenderness in the right flank. Contrast-enhanced multi-detector computed tomography findings were consistent with a perforated right colonic diverticulitis with several out-pouchings at the level of the ascending colon and evidence of free air in the right parieto-colic gutter along with an air-fluid collection within the mesentery. In addition, a ring-shaped hyperdense intraluminal material was also noted. At surgery, the ascending colon appeared irregularly thickened and folded with a focal wall interruption and a peri-visceral abscess at the level of the hepatic flexure, but no diverticula were found. A right hemi-colectomy was performed and on dissection of the surgical specimen a retained laparotomy sponge was found in the bowel lumen.