Spontaneous choledochoduodenal fistula following complete common bile duct transection from penetrating abdominal trauma: an unexpected non-operative resolution

BACKGROUND: Traumatic injuries to the extrahepatic biliary tree are extremely rare, accounting for less than 0.5% of abdominal traumas. They are often associated with severe concomitant vascular and hepatic lesions, and their diagnosis may be delayed due to overshadowing hemorrhagic injuries. Management strategies depend on the patient's hemodynamic status, ranging from primary repair in stable patients to staged damage-control procedures in unstable situations. CASE PRESENTATION: We report the case of a 29-year-old male with no medical history who presented with a thoraco-abdominal stab wound at the right seventh intercostal space. CT scan revealed a grade V hepatic injury extending to the hepatic hilum, with active bleeding from a portal vein branch and suspected common bile duct (CBD) injury. Emergency laparotomy showed a transfixing liver wound involving segments V and VII, complete transection of the CBD, and a partial portal vein injury. Hemorrhage control was achieved with Pringle's maneuver, portal vein repair, cholecystectomy, transcystic drainage, and hepatic packing. After stabilization and second-look laparotomy 48 h later, the patient developed a subcapsular biloma that was drained percutaneously. Over the following weeks, biliary drainage progressively decreased. MRCP and endoscopic evaluation at two months revealed a spontaneous choledochoduodenal fistula allowing physiological internal drainage. In the absence of biliary dilatation or hepatic dysfunction, definitive bilio-enteric reconstruction was not performed. At one-year follow-up, the patient remains asymptomatic with normal liver function. DISCUSSION: This case highlights several key aspects in the management of penetrating biliary trauma: the diagnostic limitations of imaging in the acute setting, the role of staged surgery in unstable patients, and the potential for conservative management when spontaneous internal biliary drainage develops. Spontaneous choledochoduodenal fistula formation following traumatic CBD transection is exceptionally rare, with only isolated reports in the literature. CONCLUSION: A tailored, staged approach is crucial in managing complex traumatic biliary injuries. In some fortunate situations, spontaneous choledochoduodenal fistulization can provide effective biliary drainage and obviate the need for complex reconstructive surgery, provided close follow-up is ensured.