The renal veins: a review

In clinical anatomy, the renal venous system is relatively understudied compared to the arterial system. The great complexity of the patterns and inter-relationships of the arteries and veins of the kidney is demonstrated by gross anatomical dissection and clinical practice. This review of several renal vein investigations aims to clarify and update the variable patterns of the renal venous vasculature using cadaveric human adult and foetal kidneys and to reflect on its clinical application, particularly in surgery and radiology. The study employed gross anatomical dissection and detailed morphometric and statistical analyses on resin-cast and plastinated kidneys harvested from adult and fetal cadavers. Radiological techniques were used to study intra-renal flow, renal veins and collateral pathways and renal vein valves. The gross anatomical description of the renal veins and its relations were confirmed and updated. Additional renal veins (ARV) were observed much more frequently on the right side (31%). A practical classification system for the renal veins based on the number of primary tributaries, ARV and variations is documented. Detailed morphometric analyses of the previous parameters of the renal veins corroborated and expanded previous anatomical studies. Contrary to standard anatomical textbooks, it is noted that the left renal vein is 2.5 times the length of its counterpart and that there are variable levels of entry of the renal veins into the inferior vena cava (IVC). Radiological investigations demonstrated a non-segmental and non-lobar intrarenal venous architecture, an absence of renal vein valves, and extensive venous collaterals centering mainly on the left renal vein (LRV). These collateral channels, present in the fetus and persisting in the adult, may be of operative and clinical significance in several pathological states. The applied clinical anatomy of these findings with particular regard to renal surgery and uroradiology is emphasized.