Published online February 23rd, 2010 © http://www.ijav.org Case Report International Journal of Anatomical Variations (2010) 3: 9–11 Introduction Usually, the right kidney is supplied by one renal artery, which arises as one of the lateral branches of abdominal aorta at the level of 2nd lumbar vertebra. The right renal artery passes horizontally anterior to right crus of diaphragm and behind the inferior vena cava to reach the hilum. Before reaching the hilum of the kidney, the artery divides into four or five branches. The right kidney is normally drained by one renal vein which lies in front of renal artery and passes medially to end in the inferior vena cava (IVC) [1]. Unusual vascular pattern of the kidneys are the most often encountered variations among the renal morphological variations. Variant vascular pattern have been associated with hilum of the kidney and those entering and leaving the kidney outside the hilum. Most of these variations remain undiscovered until being noticed during any surgical procedure or venography; or to be found by the forensic pathologist during autopsy. When identified, documentation of such congenital vessel variations is important as it holds many surgical and therapeutic implications. A rare case where the right kidney was supplied by an additional renal artery arising from the ventral side of the aorta, and an additional renal vein draining into IVC is reported here. Case Report The renal arteriovenous variation was observed in about 65-year-old male cadaver during the routine dissection for undergraduate medical students at Department of Anatomy, Faculty of Medicine, AIMST University, Malaysia. The specimen showed a normal right renal artery which branched from the lateral side of the aorta and then passed horizontally anterior to the right crus of diaphragm and behind the inferior vena cava to reach the hilum. Before reaching the hilum of the kidney, the artery divided into 3 branches. The additional renal artery branched from the ventral surface of the abdominal aorta slightly above the level of the normal renal artery. It then took an abrupt right turn (kink) and passed downwards and to the right crossing the normal right renal artery from front to reach the lover part of the hilum immediately above the additional renal vein. The normal right renal vein emerged from the right kidney in front of the rest of the structure at the hilum and drained into IVC. The additional right renal vein emerged from the lowermost end of the hilum passed medially below the additional renal artery to end in the IVC about 4 cm below the opening of normal right renal vein. The renal vessels on the left side were as usual (Figures 1, 2 and 3). Discussion It is widely accepted that renal vessels, especially arteries exhibit a high degree of variations. Many studies have been carried out and cases are reported about these variations. Kaneko et al. have studied 190 cadavers and reported the cases of additional renal artery emerging below the inferior mesenteric artery in 2.4% of cadavers on the right side and 1.8% on the left [2]. An angiographic evaluation of 855 cases has showed renal artery variations like multiple arteries in 24%, bilateral multiple arteries Narendiran KRISHNASAMY [1] Mohandas Rao KG [2] Somayaji SN [2] Shajan KOSHY [1] Vincent RODRIGUES [1] Faculty of Medicine, AIMST University, Semeling, Kedah, MALAYSIA [1], Melaka Manipal Medical College, Manipal, INDIA [2]. Mohandas Rao KG, PhD Associate Professor of Anatomy Melaka Manipal Medical College Manipal, INDIA. +91 984 4380839 mohandaskg@gmail.com Received July 15th, 2009; accepted December 17th, 2009 ABSTRACT Proper knowledge of variations of the vessels of the kidney is essential to the radiologists and surgeons. One such variation was observed in a 65-year-old male cadaver at AIMST University, Kedah, Malaysia. The dissection of the abdomen revealed an additional renal artery and an additional renal vein on the right side. In addition to the normal right renal artery, an additional renal artery branched from the ventral side of abdominal aorta and passed laterally to enter into the kidney through the lower part of its hilum. The additional right renal vein emerged from the lowermost end of the hilum, passed medially below the additional renal artery to end in the inferior vena cava below the opening of normal right renal vein. Further, related literature review is done and the urological implications of these variations in renal surgeries are discussed. © IJAV. 2010; 3: 9–11. Key words [renal vein variation] [renal artery variation] [additional renal vein] [additional renal artery] [additional ventral branch of aorta] eISSN 1308-4038 An unusual case of unilateral additional right renal artery and vein