Examination of collateral flow and anomalies of the left renal vein with clinical correlations.

The anatomy of the left renal vein, especially knowledge of collateral flow, is extremely important to the modern surgeon, since division of the left renal vein is common to many procedures. This study examines the left renal venous drainage system in 20 human cadavers for evidence of collateral flow and anomalies. Ten cadavers underwent dissection of the tissues surrounding the left renal vein, except for the left suprarenal and left gonadal veins, and 10 did not. Water and methylene blue were injected into the left renal vein to check for extravasation, and the veins were subsequently divided. There was no evidence of additional tributaries off the left renal vein as no extravasation occurred, and opening of the left gonadal and left suprarenal veins did not reveal any direct connections to the inferior vena cava. Thus, this experiment did not demonstrate evidence of a systemic collateral flow system draining the left kidney once the left renal vein was divided. Anomalies of the left renal venous drainage system occurred in six of 20 (30%) of cadavers, with one anomaly of the left renal vein itself (5%) manifested as a supernumerary left renal vein. The other anomalies included bifurcation of the gonadal vein, bifurcation of the suprarenal vein, the inferior phrenic vein draining into the left renal vein distal to the superior mesenteric artery, and the presence of a lumbar vein draining into the left renal vein in two cadavers. The lumbar veins may perhaps represent a normal variant.