The plain abdominal film finding of a large air-filled cavity has a differential diagnosis that includes giant colonic diverticulum, volvulus, giant Meckel's or other small-bowel diverticulum, emphysematous cystitis, vesicoenteric fistula, bowel duplication, and mesenteric cyst. The case presented here expands this differential diagnosis to include tuboovarian abscess with fistulous communication to the bowel.