An additional renal vein.

A routine cadaveric dissection in an adult male revealed the emergence of two renal veins at the hilum of the right kidney that presented two separate openings in the inferior vena cava (IVC), one above the other. At the hilum the segmental branches of the right renal artery were sandwiched between the two veins. An additional venous tributary was present posterior to the right renal pelvis. A single renal vein emerged at the hilum of the left kidney. The various tributaries observed on the right and left sides were measured. The possible developmental basis for this variation suggests the persistence of the embryonic pattern observed in the 22 mm embryo. Copyright 2002 Wiley-Liss, Inc.