Primary aortoduodenal fistula is a rare cause of gastrointestinal bleeding that is difficult to diagnose. A “herald” bleed often precedes fatal hemorrhage. Endoscopy, ultrasound, angiography and CT scan have all been utilized in an attempt to confirm this diagnosis with limited success. We report a 51-year-old male who presented with occasional melanotic stools, and then developed massive upper gastrointestinal bleeding. A primary aortoduodenal fistula was identified between an atherosclerotic abdominal aortic aneurysm, and the third portion of the duodenum in surgery. The aneurysm was resected and grafted and the duodenum repaired. The patient developed a severe coagulopathy and expired post-operatively. This case illustrates a rare presentation of both abdominal aortic aneurysm and gastrointestinal bleeding. We will discuss the challenges in diagnosis and management of this unusual problem. Introduction Primary aortoduodenal fistula (PADF) is a communication between the aorta and the enteric tract without any previous vascular intervention, e.g., aortic grafting. Although rare, PADF is a lethal condition that requires a high index of suspicion. Delay in diagnosis and treatment has been historically associated with extremely high mortality .We present a case of PADF due to an abdominal aortic aneurysm. Diagnosis was made at surgical exploration. Despite the use of angiography, and repeated computed tomography (CT) scans, the diagnosis of a PADF secondary to an abdominal aortic aneurysm is often difficult to make, leading to a delay in diagnosis until the time of surgery [2]. This extremely rare condition requires a high index of clinical suspicion even in a patient with undiagnosed aortic disease. Case Report A 51-year old male presented to the emergency room with a chief complaint of rectal bleeding. The patient reported intermittent bleeding for one year which had worsened over the past two days. He also reported feeling “dizzy” with occasional bright red blood per rectum.PMH was significant for hypertension, non-insulin dependent diabetes, peptic ulcer disease, GERD, and osteomyelitis of his cervical spine. No surgical history. Current medications included Glucophage, Lipitor, and Lisinopril. No history of drug, alcohol or tobacco use. Review of systems was otherwise non-contributory.The patient appeared in mild distress, was well hydrated, alert and oriented heart rate 108, blood pressure 106/61 with no orthostatic changes. Pulses were palpable at 2+ throughout. Abdomen was soft and mildly tender in the epigastrium. Rectal exam revealed gross blood.Lab work was unremarkable except for hemoglobin of 11g/dl and BUN/Cr 33/l.4. A nasogastric tube was placed. His stomach was lavaged with no blood. The patient was admitted with the diagnosis of GI bleeding of unknown etiology. EGD was performed which showed mild gastritis and duodenitis but no bleeding. Two days later the patient passed another 500ml of melana, received two units of PRBC and underwent colonoscopy which was unremarkable. His bleeding stopped and a subsequent barium small bowel study failed to show a mass or lesion. Plans were made for CT/ angiogram.Day six after admission, the patient had abdominal pain, a large upper GI bleed and melena. Repeat EGD showed a large clot in the third portion of the duodenum. Exploratory laparotomy revealed a communication between the aorta and third portion of the duodenum. The aneurysm was resected and grafted and the duodenum repaired. Unfortunately, the patient developed severe coagulopathy and expired six hours postoperatively. Discussion The most common site of aortoenteric fistulization is at the third portion of the duodenum because of its fixed retroperitoneal location overlying the aorta. While this condition is extremely rare with an incidence rate at autopsy of 0.04 to 0.07%, secondary ADF occurs much more commonly (post-operative incidence -0.5 to 2.3%), and is due to prior aortic surgery and/or the placement of a synt
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