1294 Large Common Bile Duct Stones Creating a Rare Distal Choledochoduodenal Fistula Requiring Unusual Extraction Method

Abstract

INTRODUCTION: Choledochoduodenal fistulas (CDF) are abnormal connections of the common bile duct to the duodenum separated into proximal and distal. Of the various enterobiliary fistula, the most common is cholecystoduodenal. The rare occurring distal CDF etiologies include cholecystolithiasis, malignancy, peptic ulcers and iatrogenic. In the case presented, common bile duct (CBD) stones were large enough to create a fistula from the common bile duct superior to the sphincter of Oddi requiring unique extraction. CASE DESCRIPTION/METHODS: A 75-year-old Caucasian female with past medical history significant for biliary colic status post cholecystectomy was found to have multiple large CBD stones on abdominal ultrasound outpatient. Physical exam and laboratory analysis was unremarkable. When the ERCP was performed, the papilla was identified and noted be abnormal. The papilla was downward facing. Shockingly, superior to the papilla was a CDF created by an impacted black CBD stone. Subsequently to this unexpected finding, selective deep cannulation of CDF, adjacent to the CBD stone, was done using a sphincterotome with a 0.035 wire. No attempts were made of cannulating the papilla. The cholangiogram showed multiple CBD stones throughout the distal CBD. A 13 mm sphincterotomy superiorly at the CDF, followed by balloon sweeps removing several large yellow cholesterol appearing stones. DISCUSSION: Distal CDF is diagnosed via endoscopy and categorized based on location using the Ikeda classification. Type 1 (distal) fistulas occur along longitudinal fold adjacent to the papilla, often due to an impacted stone. Type 2 (proximal) occurs on the posterior wall of the duodenal bulb. The classification system further separates CDF into type A, opening greater than 2 cm from the papilla, type B, opening within 2 cm from the papilla, and type C, opening on the papillary fold. In this rare case of distal CDF, the diagnosis was likely type 1A (distal and greater than 2 cm from the papilla). Treatment is often based upon the etiology of CDF formation. Given the rare occurrence, it is important for gastroenterologist to be aware of the classifications as it may assist in treatment and safe stone removal.