Case report: gastrointestinal hemorrhage caused by a pancreas transplant arteriovenous fistula with large psuedoanuerysm 9 years after transplantation

Reported cases of arteriovenous fistulae in transplant recipients are uncommon. We present a case of an arteriovenous fistula associated with a large pseudoaneurysm in the root of the small bowel mesentery of a pancreas transplant. Uniquely, in our case, the arteriovenous fistula presented with an episode of gastrointestinal (GI) hemorrhage 9 years postoperatively. Radiographic imaging including coronal computed tomography angiogram and conventional angiogram demonstrated an arteriovenous fistula in the patient's pancreas transplant between the distal superior mesenteric artery (SMA) and superior mesenteric vein (SMV) with 6 cm aneurysmal dilatation. The tremendous flow in the fistula in the root of the graft small intestine mesentery led to graft duodenal mucosal congestion and lower GI hemorrhage. After successful embolization of the SMA–SMV fistula and pseudoaneurysm using interventional radiographic techniques, the arteriovenous fistula remained thrombosed. The patient had no further episodes of GI bleeding and her endoscopic evaluation was otherwise negative. The presence of arteriovenous fistulae and pseudoaneurysms in pancreas transplant recipients is uncommon, but has been previously documented. This case is further distinguished from previous reports by the notable 9-year interval between transplantation and the onset of hemorrhage. Historically, symptomatic vascular malformations have been associated with significant patient morbidity and mortality. Successful patient management involves timely and accurate diagnosis and intervention.