Anomalous channels draining the internal iliac veins: embryological and clinical significance

During a routine cadaver dissection, we have encountered an anomalous formation of inferior vena cava and abnormal channels communicating the two internal iliac veins with the inferior vena cava in a 67 year old male cadaver. The said channels which had a caliber of 5 mm on the left side and 15 mm on the right arose at a distance of 26 mm on the left and 35 mm on the right from the internal iliac vein termination. Both the said channels moved medially and joined one another and formed a common stem (Cs) which finally terminated at the junction of the termination of right iliac vein into the inferior vena cava. The lumen of the terminal part had a diameter of 18 mm and it was 20 mm in length. Anomalies of the inferior vena cava and renal veins occur infrequently but if unidentified can lead to significant morbidity during surgical exploration. An understanding of the embryologic development of the vena cava and its tributaries is necessary to understand the genesis of these sometimes complex anomalies and their accompanying anatomic variants.