Venous anomalies encountered in aortoiliac surgery.

Reconstructive procedures of the aortoiliac system are extremely common. Aside from ruptured aneurysms, most severe intraoperative hemorrhage is due to venous injuries. The ability to recognize and manage venous anomalies is essential. This article presents a review of major venous anomalies including (1) transposition of the inferior vena cava, (2) double vena cava, (3) retroaortic left renal vein, (4) circumaortic renal collar, and (5) preaortic iliac venous confluence. Embryologic development, operative recognition, and techniques of operative management are discussed. A case report is presented in which an anomaly similar to a preaortic iliac confluence was discovered during aortic reconstruction for a ruptured abdominal aortic aneurysm. This case differs from previously reported cases of preaortic iliac confluence in that the right common iliac vein persisted in its course anterior to the right common iliac artery.