Gallstone ileus (GSI) of the colon is an extremely rare cause of large-bowel obstruction. It has been shown to account for 2% to 8% of all cases of GSI [1
]. It is a disease of the elderly with considerable morbidity and mortality.
The mechanism of obstruction usually results from a large gallstone greater than 2
cm in diameter entering the colon through a cholecystocolonic fistula. The fistulous connection usually forms after a preceding episode acute cholecystitis leads to inflammation and adhesions forming between the gallbladder and colon, usually at the hepatic flexure. The gallstone impacts distally and causes a mechanical obstruction. The point of impaction is usually a pathological narrowing of the colon which may be a result of diverticular disease [3
] or prior pelvic irradiation [5
The typical presentation is that of large-bowel obstruction with abdominal pain and distension being the main features. However, rarer presentations such as diarrhoea or ascending cholangitis can occur [6
]. As in GSI of the small bowel, the classic X-ray triad of bowel obstruction, pneumobilia, and ectopic gallstones [7
] is sometimes but not always seen. Contrast-enhanced computed tomography allows better visualisation of the point of obstruction and site of fistula [8
About 7% of GSI have been shown to settle with conservative management. However, in the majority of cases operative management is required. In the main part operative intervention for colonic GSI is the same as small bowel GSI. The definitive management involves enterolithotomy, cholecystectomy, and fistula closure at one operation [10
]. This allows relief of the obstruction as well as preventing further stone formation and episodes of cholangitis. For the higher-risk patient such as in our report a single stage enterolithotomy alone may be more appropriate. During either operation the entire length of the small and large bowel should be examined for additional occult stones. Management by colonoscopy and extraction has been successful in few cases [11
]. However when the stone is relatively large and the lumen is relatively small, it is less likely to be successful [13
In conclusion GSI of the colon is a rare but important cause of large-bowel obstruction. The diagnosis may be very difficult given the lack of distinguishing clinical features but should be considered if there has been a history of gallstone disease. If plain abdominal films do not reveal the diagnosis, computed tomography will allow visualisation of the fistula and level of obstruction. Treatment depends on the fitness of the patient but should ideally involve relief of the obstruction, cholecystectomy, and repair of the fistula.