Spontaneous aortoenteric fistula involving the sigmoid: A case report and review of literature

INTRODUCTION: Primary aortoenteric fistula (PAEF) is a pathological communication between the aorta and any portion of the gastrointestinal tract. The pathology is very rare and easily overlooked during the diagnostic process. PRESENTATION OF CASE: We report the exceptional case of an 86-year-old man with episodes of abdominal pain and rectal bleeding of unknown cause over a period of 1,5 months due to a PAEF to the sigmoid. A sigmoidectomy was performed and a rifampicin-soaked aortic graft was placed. The patient had an uneventful post-operative recovery. The duration of symptoms, the anatomic location of the fistula and the outcome after surgery makes this case unique. DISCUSSION: With an incidence of 0.04–0.07% in all patients with aortic aneurysms a PAEF is very rare. Only 2% of PAEF's involves the sigmoid. The most common cause is an atherosclerotic aortic aneurysm. Patients with PAEF can present with a triad of symptoms including gastrointestinal bleeding, abdominal pain and a pulsating mass. A contrast-enhanced computer-tomography scan (CTa) is the most accurate tool to demonstrate a PAEF. Without a strong clinical suspicion, diagnosing a PAEF is hard and frequently delayed. The overall PAEF-related mortality is high (61–100%) and decreases after surgery (30–40%). CONCLUSION: A primary aortoenteric fistula involving the sigmoid is very rare. Clinical presentation can vary, diagnosis can be difficult and surgical options may differ. Even with low suspicion of PAEF, we recommend performing a CTa. With a high overall mortality of more than 60% due to exsanguinating, surgical treatment is always indicated.