Incidental aortocaval fistula in the setting of an unruptured abdominal aortic aneurysm.

An aortocaval fistula, a rare abnormal vascular communication between the aorta and inferior vena cava, is most commonly associated with abdominal aortic aneurysms (AAAs). Other factors leading to aortocaval fistula formation include atherosclerosis, collagen vascular diseases, vasculitis, hematogenous infections, prior spinal surgery, malignancy and radiation exposure. In rare instances, aortocaval fistulas may be discovered incidentally on abdominal imaging. We report an unusual case of an incidental aortocaval fistula in a 93-year-old male patient with an unruptured AAA, presenting with shortness of breath, malaise and lethargy. The patient had no other obvious risk factors for aortocaval fistula formation. Multidetector computed tomography angiography helped identify the fistula, and the patient was eventually transferred to hospice for comfort measures. This case highlights the importance of detailed imaging and preoperative planning in managing aortocaval fistulas and associated AAAs.