S2823 Primary Aortoenteric Fistula as a Rare Cause of Gastrointestinal Bleeding

Abstract

INTRODUCTION: Aortoenteric fistulas (AEF) are formed by an abnormal connection between the aorta and gastrointestinal tract, usually the duodenum, that can lead to life-threatening gastrointestinal hemorrhages. Fistulas can present de novo, known as primary fistulas, or as secondary AEF, which occur due to surgical aortic interventions such as aortic grafts. The annual incidence of primary AEF is 0.007 per million while the incidence of secondary AEF due to aortic repair is 0.6–2%. We present a case of primary Aortoenteric fistula with no prior surgical interventions. CASE DESCRIPTION/METHODS: A 51-year old patient with a past medical history of hypertension, coronary artery disease, and tobacco use was arrived to the hospital with complaints of bright red blood per rectum. A CT abdomen/pelvis revealed a 6.4 cm infrarenal aortic aneurysm (AA) and a right common iliac artery aneurysm with complete thrombosis of the external iliac artery. An EGD showed the duodenum with an opening and oozing fresh blood suggestive of an AEF, along with a pulsatile mass, most likely the AAA. Patient was then emergently taken to the OR and had an endovascular stent placed with successful exclusion of the infrarenal aortic aneurysm. Thereafter, a colonoscopy performed by colorectal surgery showed a large pulsatile blue mass extrinsically compressing the colon in multiple locations; subsequently aborted at the splenic flexure due to this extrinsic compression. The patient then underwent open repair which found an aortoduodenal fistula in the 4th duodenal segment. The duodenum was resected with primary anastomosis, the aortic stent was explanted, aortic aneurysm resected, and reconstruction performed. After surgery, the patient improved clinically and had no further bleeding. DISCUSSION: Primary AEFs are a devastating condition which are difficult to identify. The likely cause, an abdominal aortic aneurysm, can be clinically silent and typically lack any history of prior aortic surgical interventions. When symptoms do occur, it is typically GI bleeding ranging from mild to an exsanguinating hemorrhage, with other nonspecific symptoms including malaise, weight loss, and abdominal pain. CT angiography is a quick initial diagnostic tool but if there was no prior suspicion of primary AEF, an EGD would reveal a clot or fresh blood in the duodenum. With such findings on endoscopy, it is important to quickly involve vascular surgery for emergent repair via open or endovascular techniques to avoid adverse outcomes.Figure 1.: Endoscopic view of primary Aortoenteric Fistula in the duodenum.