Aneurysmal Veins in Free Flaps: A Rare Case Report and Discussion.

Microvascular anastomosis is a fundamental technique in reconstructive surgery, where careful selection and meticulous handling of vessels are critical in preventing thrombosis-the leading cause of flap failure. Despite the extensive literature surrounding the topic, aneurysmal veins-typically identified incidentally on imaging or occasionally presenting with thrombosis when located in the deep veins of the extremities-are seldom encountered in the context of microsurgery due to their overall rarity. In this case report, we describe our intraoperative encounter with aneurysmal veins during free flap reconstruction. We outline our attempts to use and salvage these aberrant vessels for microvascular anastomosis, describing the technical difficulties that were encountered along the way. Serving as a cautionary tale, we explain what should be done when such unusual veins are encountered.