Confluence of the right internal iliac vein into a compressed left common iliac vein.

The authors describe the abnormal confluence of the right internal iliac vein into a left common iliac vein compressed by the overlying right common iliac artery. The prevalence of this combination of abnormalities, evaluated in cadavers and in living subjects by CT, was 0.9%. The possible obstacle to venous pelvic return by these anomalies is pointed out.