Anomalies of inferior vena cava and left renal vein: risks in aortic surgery.

Although most aortic surgery is now routinely performed without incident, major venous anomalies can cause unexpected bleeding. In the last 6 years, 4 of 166 patients undergoing abdominal aortic surgery at our institution were found to have a major venous anomaly, including a double inferior vena cava (2), a preaortic iliac vein confluence (1), and a circumaortic renal collar (1). The 3 men and 1 woman had a mean age of 62.3 years (range, 56 to 68 years). All four patients underwent surgery for an abdominal aortic aneurysm. Preoperative imaging revealed all of the venous anomalies except for the renal collar. Unexpected venous injuries complicated the operation in one patient who had a double inferior vena cava and an inflammatory abdominal aortic aneurysm and in the patient with the circumaortic renal collar. Major venous anomalies are rarely encountered in patients undergoing aortic surgery. Preoperative assessment and intraoperative awareness are important to prevent unexpected venous injuries. Patients with an anomaly of the left renal vein and an inflammatory abdominal aortic aneurysm are at a particularly high risk.