An unusual variation of the left renal vessels: a case report

Introduction Renal arteries are a pair of lateral branches of the abdominal aorta, arising at the level of L1 & L2 vertebra, just below the origin of the superior mesenteric artery. Renal arteries course anterior to the renal pelvis before entering the hilum. Right renal artery is longer and passes posterior to the inferior vena cava, whereas the left renal artery passes behind the left renal vein, the body of pancreas and splenic vein. A single main renal artery is seen in 70% of individuals, and accessory renal arteries are common (30%) and usually arise from the aorta above or below the main renal artery and follow it to the renal hilum. These accessory renal arteries are called as persistent embryonic lateral splanchnic arteries [1]. Near the hilum, each renal artery divides into anterior and posterior divisions which further divide into segmental, lobar, interlobar and arcuate arteries. These are end arteries with no anastomoses. Generally, each kidney is drained by a single renal vein at the hilum of kidney. Right renal vein is shorter and drains into inferior vena cava, whereas the left renal vein is three times longer than the right renal vein and drains into inferior vena cava by coursing anterior to the aorta. In addition, left renal vein also receives tributaries of left gonadal vein from below and left suprarenal vein from above. Left renal vein may be double, one vein passing anterior and the other passing posterior to the aorta before draining into inferior vena cava. This is referred to as persistence of the ‘renal collar’ [1]. Accessory renal vein running posterior to the aorta may be compressed by aorta and leads to retrograde increase in venous return which increases pressure in gonadal veins (present case) leading to varicosity of veins and nutcracker syndrome. Accessory renal arteries are end arteries which supply particular segment of the kidney, and its accidental damage may lead to ischemia of that region [2, 3]. Accessory renal arteries may also compress upon the ureter causing hydronephrosis. Thus, a thorough knowledge of these variations is important for surgeons, urologists and radiologists.