Rare variation in course and affluence of internal iliac vein due to its anatomical and surgical significance.

During regular dissection of the retroperitoneal region, three uncommon anatomical variations of the internal iliac veins were found on dissected specimens: in the first case, the internal iliac veins converge forming a common trunk draining into the left external iliac vein. In the other two cases, the internal iliac vein crosses the median plane and flows into the contralateral common iliac vein. These anomalies result from a persistence of the embryonic inferior branch of the cardinal vein and are important to be known for they may be undetected or may not appear in imaging. These data have implications for both pelvic surgeons and anatomists who manipulated this anatomical area.