S4664 Rare Location of Arterio-Enteric Fistula in a Patient With a Pancreatic Transplant

Introduction: Arterio-enteric fistulas (AEFs) are rare, potentially fatal causes of gastrointestinal (GI) bleeding due to communication between an artery and the bowel. In pancreas transplant recipients, AEFs most commonly develop at the interface between the arterial Y-graft—typically constructed from donor iliac artery—and the donor duodenum, which is anastomosed to the recipient’s small bowel for enteric drainage. Local infection, rejection, or pseudoaneurysm formation can result in arterial erosion into adjacent bowel, leading to massive GI bleeding. Endoscopic findings are often nondiagnostic. This is a rare case of AEF from a ligated transplant artery stump to the colon, an unusual site likely reflecting atypical distal enteric drainage during pancreas transplantation. Case Description/Methods: A 47-year-old woman with type 1 diabetes and end-stage renal disease, failed kidney and pancreatic transplants, nephrectomy of the transplant kidney, and history of deep vein thrombosis on apixaban presented with intermittent hematochezia for 1 month. Prior esophagogastroduodenoscopy (EGD) and colonoscopy were unrevealing. She initially presented to an outside hospital in hemorrhagic shock (hemoglobin 4.9 g/dL), requiring transfusion and cessation of anticoagulation. Upon transfer, she had recurrent large-volume hematochezia requiring massive transfusion. Computed tomography angiography revealed active bleeding in a right lower quadrant bowel loop adjacent to a ligated transplant artery from the right common iliac artery. A mesenteric angiogram showed no active bleeding. She was transferred to a higher center, where repeat EGD and colonoscopy were nondiagnostic. After another hemorrhagic episode, emergent angiography revealed a large arterio-enteric fistula between the transplant artery stump and adjacent colon, with brisk bleeding. Hemostasis was achieved via placement of a covered balloon-expandable endograft in the right iliac artery. Hematochezia resolved, and anticoagulation was safely resumed. Discussion: This case highlights a rare arterio-enteric fistula between a ligated transplant artery and the colon—an unusual site not typically involved in post-transplant AEFs. The shared transplant artery from the right common iliac likely supplied both renal and pancreatic grafts and was ligated after graft failure. Fistula formation into the colon caused intermittent hematochezia. This case underscores diagnostic challenges when initial endoscopies are unrevealing and demonstrates the value of endovascular therapy in managing complex post-transplant vascular complications.