Several renal veins drain each kidney and unite in a variable fashion to form the right and left renal veins; these veins lie anterior to the right and left renal arteries. The longer left renal vein receives the left suprarenal vein, the left gonadal (testicular or ovarian) vein, and a communication with the ascending lumbar vein; it then traverses the acute angle between the superior mesenteric artery anteriorly and the aorta posteriorly. Each renal vein drains into the inferior vena cava.