Cholecysto-duodenal fistula

A cholecysto-duodenal fistula is a connection between the gallbladder and the duodenum. It may occur as an uncommon complication of chronic cholecystitis when the gall bladder becomes adherent to the adjacent duodenum and a stone ulcerates through the wall to form a cholecysto-duodenal fistula.

The fistula allows decompression of the gall bladder and passage of gallstones from the gall bladder into the bowel, and also allows gas to enter the biliary tree.

This condition is often harmless, and only manifested as gas in the biliary tree on plain abdominal X-ray. However, sometimes a large stone may pass through the fistula and then becomes 'stuck' at the narrowest part of the small intestine, the distal ileum. This in turn leads to the development of a gallstone ileus.

CT imaging is considered more accurate than X-ray than ultrasound for the detection of both a fistula and gallstone ileus, and allows direct visualisation of a tract between the gallbladder and the duodenum.

Fistulas may develop between the gallbladder and other parts of the gut, e.g. colon and very rarely, stomach.

Reference

1. Pickhardt PJ, Bhalla S, Balfe DM. Acquired gastrointestinal fistulas: classification, aetiologies, and imaging evaluation. Radiology. 2002;224 (1): 9-23.