We report a 67-year-old female that had a laparoscopic cholecystectomy complicated by common bile duct (CBD) and right hepatic artery injuries. A catheter was placed into the proximal common bile duct to create an external biliary fistula. The catheter eroded into the edge of the CBD and that irritation caused a choledochoduodenal fistula to form. To our knowledge, this is the first reported case in which an external biliary catheter caused the formation of a choledochoduodenal fistula after a bile duct injury from a laparoscopic cholecystectomy.