Spontaneous biliary-colonic fistula in association with biliary calculus disease

Clinical History

A 34-year-old male patient presented with history of right upper abdominal pain of 1 week duration. He also complained of diarrhoea for the past 2 to 3 months. He had undergone cholecystectomy 2 years ago for cholelithiasis.

Imaging Findings

A large calculus is visualised within the proximal aspect of the left hepatic duct near its confluence with the right hepatic duct causing significant dilatation of the intrahepatic biliary radicles in left lobe of liver. Another calculus is visualised within one of the dilated intrahepatic radicles in left lobe of liver. A small calculus is also visualised in the distal common bile duct.
Significant air pockets are noted within the right hepatic duct and intrahepatic biliary radicles in right lobe of liver in keeping with pneumobilia. No air pockets are noted within the dilated biliary radicles in left lobe of liver. The hepatic flexure of colon is noted in close proximity to the inferior surface of liver with a well-defined tract connecting the right hepatic duct and the hepatic flexure of colon. The common hepatic and common bile duct could not be visualised, likely due to decompression by proximal fistula.

Discussion

Biliary enteric fistulas comprise a rare group of disorders. Among these, cholecystoduodenal fistulas are the most common group constituting about 70 %, while cholecystocolonic fistulas constitute about 8 to 26% [1, 2]. Choledochoduodenal fistulas are extremely rare with only a few cases reported in literature. Reported associations include possible cholangitis, agenesis of gall bladder, cholangiocarcinoma, cystic duct remnant and common bile duct calculus [3, 4, 5, 6, 7]. Biliary calculus disease was also the presumed cause of fistula formation in our case. Common presenting complaints in patients with a biliary enteric fistula include abdominal pain and diarrhoea. Steatorrhoea and an increased risk of recurrent cholangitis have also been described [1, 3].
Pneumobilia detected on plain radiographs, ultrasound and CT examinations is suggestive of biliary enteric fistula formation in the right clinical setting. Barium studies and hepatobiliary scintigraphy have been used to diagnose biliary colonic fistulas in a few reported cases [3, 8].With the advent of thin section isovolumetric images in CT and MRI it is likely that the actual fistulous communication will be visualised more often using these modalities.
Our case had cholecystectomy for cholelithiasis two years prior to presentation. The calculi within the hepatic duct and intrahepatic biliary radicles might have been missed prior to surgery or new calculi might have formed later. It is likely that the small calculus in the distal common bile duct obstructed biliary drainage, thus facilitating formation of an alternative route of drainage through the adjacent hepatic flexure of colon. On CT, where subjects are routinely examined in supine position, air pockets in the biliary tree usually ascend into the non-dependent biliary radicles of the left lobe of liver. The presence of pneumobilia exclusively within the radicles in the right lobe of liver along with dilatation of the radicles in the left lobe of liver in our case necessitated a search for possible obstruction to the left hepatic duct and aided in confirming the location of the large calculus. This type of spontaneous biliary enteric fistula where the fistulous tract exclusively connected biliary radicles, draining only one lobe of the liver with the colon, has not been previously documented to the best of our knowledge.
Treatment is directed towards the underlying cause for the fistula, calculus disease in this case. Definitive treatment involves surgical excision of the fistulous tract with some form of anastamosis between the biliary tract and duodenum/jejunum for biliary drainage [3, 9].

Differential Diagnosis List

Final Diagnosis

Biliary-colonic fistula in association with biliary calculus disease

URL:	https://www.eurorad.org/case/10746
DOI:	10.1594/EURORAD/CASE.10746
ISSN:	1563-4086