A Pseudoaneurysm Situated Within the Wall of a Venous Aneurysm: A Case Report

Venous aneurysms and pseudoaneurysms are common complications of repeated cannulation (venipuncture) of the efferent (outflow) veins in patients with arteriovenous fistulas on hemodialysis. A true venous aneurysm is an abnormal dilatation that over-distends the 3 layers (tunica intima, media, and adventitia) of the venous wall without any mural rupture. Venous aneurysms, similar to arterial aneurysms, do not have necks, unlike vascular pseudoaneurysms. A venous pseudoaneurysm, by contrast, has an abnormally dilated wall with 1 or 2 of the 3 mural layers torn, resulting in a focal outpouching. Vascular pseudoaneurysms have a neck and sac that could be partially or completely thrombosed. Rarely, vascular pseudoaneurysms could develop within the wall of already existing true aneurysms or other pseudoaneurysms. Such development would require careful monitoring and could also necessitate surgical revision. This patient case demonstrates a rare occurrence of a pseudoaneurysm within the wall of a venous aneurysm.