“You mean it's not cancer?”: Choledochoduodenal fistula, a rare cause of biliary obstruction

Background

Choledochoduodenal fistula is a rare and poorly understood condition that results from the anomalous formation of a communicating tract between the common bile duct and the duodenum. While the precise etiology is not understood there has been a notable increase in identified cases in the last 20 years. The symptoms of choledochoduodenal fistula are vague and it is often not diagnosed until the patient develops cholangitis.

Case report

A 70yo M with a recent diagnosis of hepatitis C presented to the emergency department for evaluation of jaundice. Ultrasound demonstrated a hydropic gallbladder with “double duct” sign. The patient was admitted to the hospital and underwent ERCP. This identified a choledochoduodenal fistula which was treated. On follow up the patient had marked improvement with no significant sequelae or complications.

Why should an emergency physician be aware of this?

Choledochoduodenal fistula is a rare and poorly understood pathology. However, choledochoduodenal fistula “attacks” are strongly associated with cholangitis which has a mortality approaching 5 ​% even when appropriately managed (Sokal et al., Dec 2019) [1]. In our case, neither ultrasound nor portal vein-phased CT demonstrated the Choledochoduodenal fistula and ERCP was required both to identify and treat the fistula. In the setting of obstructive jaundice, it may be prudent for the emergency physician to consider transfer to a center with ERCP capability if it is not readily available in their facility.