Iliac Artery-Inferior Vena Cava-Duodenal Fistula: An Unusual Cause of Massive Gastrointestinal Bleeding.

An arteriovenous-enteric fistula is a 3-way connection between the vascular and enteric system and associated with high mortality. We describe a case of iliac artery-inferior vena cava-duodenal fistula in a young female with a retroperitoneal mass presenting with sepsis and hemorrhagic shock with a catastrophic clinical course. These fistulas can be missed on endoscopy/colonoscopy and are usually diagnosed on computed tomography angiogram of the abdomen. Complex vasculoenteric fistula should be among differentials in patients presenting with gastrointestinal bleeding, especially with a history of malignancy, radiation, foreign bodies, and trauma. The management is complex and should involve a multidisciplinary approach involving vascular surgery, intervention radiology, and gastroenterologist.