A biliary fistula is suspected in people who have had a history of cholelithiasis, peptic ulcer disease, Crohn's disease, biliary infections (e.g. hydatid disease), malignancies of the gastrointestinal (GI) tract or in those who have recently been surgically operated upon. Most patients are asymptomatic with overt clinical manifestations visible only in 20-30% of cases . Symptoms are usually non-specific and are noticed in a variety of GI disorders. The diagnosis is thus, easily missed in the early stages of the disease.
Amongst individuals who do present with symptoms, abdominal pain may be a frequent finding if the fistula tracts are infected. Other complaints that may be seen include nausea, vomiting, diarrhea, fever, flatulence and weight loss. Cholangitis may lead to systemic manifestations like sepsis and peritonitis. Ascites may be observed in a few people.
Jaundice secondary to common bile duct obstruction or due to strictures of the bile duct (Mirizzi's syndrome) may be recorded . Gallstones may pass into the gastrointestinal tract via these abnormal connections and may cause small bowel obstruction, especially in the terminal ileum (Bouveret's syndrome) . Abdominal pain, vomiting, and constipation ensue in such patients.
In rare instances, fistulas may form between the biliary tree and the pleural/ bronchial spaces with pulmonary complaints occurring in such individuals.
Patients presenting with clinical features suggestive of a biliary fistula are often diagnosed via surgery, with preoperative confirmation occurring only in 8-17% of all affected cases . In such a scenario, most investigations are geared towards determining the type of surgery that needs to be conducted. This, in turn, is dependent on the likely etiology of the fistula, the presence of biliary tree obstruction/ erosion and the coexistence of a bilioenteric fistula.
Gallstones, the most common cause of a biliary fistula, are easily diagnosed by a transabdominal ultrasound (US) with a sensitivity of 96% . Similarly, Mirizzi's syndrome can be detected via the transabdominal US with a sensitivity of 29% . Magnetic resonance cholangiopancreatography (MRCP) may offer a higher accuracy in the evaluation of this disorder. It can be used to delineate other abnormalities seen in the biliary tract.
A computed tomography (CT) scan may help in locating the level of biliary tree obstruction. Aerobilia, a frequent sign of a bilioenteric fistula, may be easily observed via US or CT. A CT scan may help to rule out the presence of intestinal obstruction due to biliary stones and/or hepatic neoplasms.
The evaluation of these lesions may be determined by certain invasive studies . Although the usage of endoscopic ultrasound (EUS) for recognizing biliary fistulas is still uncertain, some reports have shown that Mirizzi's syndrome can be reliably confirmed with EUS with 97% sensitivity and 100% specificity   . Endoscopic retrograde cholangiopancreatography (ERCP) shows up to 90% accuracy in diagnosing primary biliary fistulas and it may also have a therapeutic role in such cases, assisting in stone retrieval and biliary tract drainage via stents .
Laparoscopic cholecystectomy may be used to identify the site, size and potential cause of biliary leaks. A percutaneous transhepatic cholangiography is reserved for people with a completely stenosed biliary tree.