Gallstone ileus of the sigmoid colon is an important, though extremely rare, cause of large bowel obstruction. The gallstone often enters the large bowel through a fistula formation between the gallbladder and colon, and impacts at a point of narrowing, causing large bowel obstruction. We describe the case of an 80-year-old woman who presented with features of bowel obstruction. Multiplanar abdominal CT demonstrated a cholecystocolonic fistula in exquisite detail. The scan also showed obstruction of the colon due to a large gallstone impacted just proximal to a stricture in the sigmoid. Owing to inflammatory adhesions and a stricture from extensive diverticular disease, the gallstone could not be retrieved. This frail and elderly woman was treated with a loop colostomy to relieve bowel obstruction. The patient made an uneventful recovery.
2015 BMJ Publishing Group Ltd.