Background: To define the signs useful for differentiating between gallbladder-enteric fistula (GB-EF) and common bile duct-enteric fistula (CBD-EF) on computed tomography (CT) because the prognosis and management of the two are different.
Methods: CT scans in 13 patients with pneumobilia, who had not had surgical biliary-enteric anastomosis and endoscopic sphincterotomy, were reviewed. The presence of fistula itself, the location of air in the biliary system, and the appearance of the gallbladder were assessed.
Results: The causes of pneumobilia were GB-EF in seven patients, CBD-EF in three patients, emphysematous cholecystitis (EC) in one patient, gallbladder cancer (GBC) in one patient, and incompetent sphincter of Oddi in one patient. In three of seven GB-EF patients (43%) and in none of the three CBD-EF patients (0%), the fistula itself was detected. Air was detected in the common bile duct in four of seven GB-EF (57%) and in all three CBD-EF (100%) patients, and GBC. In six of seven GB-EF (86%) and in one of three CBD-EF (33%) patients, the gallbladder was contracted. Thus, the location of air and the contraction of gallbladder were useful signs to differentiate GB-EF from CBD-EF.
Conclusion: CT can distinguish between GB-EF and CBD-EF.