The renal veins in the human cadaveric fetus: their importance as contributors to collateral flow.

The venous collateral flow emanating from and around the renal veins was investigated in the human cadaveric fetus. Experimental venous occlusion was performed along several venous pathways under the sphere of influence of the renal veins in 11 fetuses. Radiological techniques were used to investigate renal venous collateral flow. Extensive venous collaterals centered on the left renal vein were observed. It is concluded that the left renal vein is a major venous collateral pathway in the fetus whereas the right renal vein contributes little. This potential for collateralisation may be operative in the adult and may play a dominant role in disease states.