Prepared by Ayodele Osowo, MD, and Ikenna Osuorji, MD, Department of Medicine, Unity Health System, Rochester, NY

A 68-year-old Caucasian woman with steroid-dependent rheumatoid arthritis and diverticulosis presented with progressive abdominal distension and pneumaturia of 1 week's duration. Plain abdominal radiograph revealed a massive radiolucent pelvic shadow (Figure), reported as a 25-cm, grossly dilated cecum suggestive of a cecal volvulus. While the patient was waiting for a computed tomography (CT) scan and possible emergency surgery, catheterization of the urethra produced a loud gush of air. Results of a subsequent CT scan of the abdomen and repeat abdominal radiograph were unremarkable. The presumptive diagnosis of colovesical fistula was confirmed intraoperatively, and the defect was repaired.

Diverticulitis accounts for 40% to 90% of cases of colovesical fistula.

Figure —Abdominal radiograph showing a 25-cm, massively dilated radiolucent pelvic shadow.

Points to remember: Simple bedside urethral catheterization may help differentiate a dilated urinary bladder from a dilated sigmoid colon or cecum.

Diagnosis: Colovesical fistula.