Two rare anomalies of the left renal vein.

Two uncommon anatomical variations of the left renal vein were found on dissected specimens: a circumaortic venous ring and a retro-aortic bifid left renal vein. The first anomaly results from a persistence of the embryonic renal venous collar. The second one would be related to a particular pattern of left inferior vena cava. Both abnormalities have to be known for they may be undetected or be misleading in imaging. Other clinical implications are also considered.