Abnormal origin of left ovarian artery from the inferior renal polar artery - A rare anatomical variation

Anatomical variations of the renal arteries and gonadal arteries are not uncommon owing to their embryological origin. Awareness of possible anatomical variations of the renal artery and gonadal artery is essential for surgeons who perform open and minimally invasive procedures of the kidneys and retroperitoneal region to prevent disastrous haemorrhagic complications during those procedures and for radiologists to prevent misinterpretations of imaging and to prevent vascular complications during interventional procedures. The present report describes an unusual variation of the left ovarian artery arising from the inferior renal polar artery which originated from the abdominal aorta superior to the main renal artery.


Introduction
The renal arteries are a set of paired branches of the abdominal aorta arising just below the origin of the superior mesenteric artery 1 . Both renal arteries cross the corresponding crus of the diaphragm at right angles to the aorta and enter the renal hilum in between the renal vein and the ureter at the level of the first lumbar vertebra. The right renal artery is longer and often higher than the left. Although a single renal artery supplying each kidney is classically described, it is subject to anatomical variations frequently 2 . Knowledge of these anatomical variations of the renal vasculature is of great importance with the advent of vascular reconstructive surgeries, renal transplants, and various radiological and urological procedures carried out in this region 2 .
The renal arteries themselves may vary in their level of origin, calibre and obliquity. They give off branches to suprarenal gland, ureter, renal capsule, perinephric tissue and the renal pelvis in their extrarenal course 1 . Near the renal hilum, each renal artery divides into anterior and posterior divisions, which in turn divide into segmental arteries supplying the renal segments. Accessory renal arteries which are believed to be derived from persistent embryonic lateral splanchnic arteries are not uncommon findings 1,2 . They can be found in more than 30% of the population and usually arise from the aorta below (less commonly above) the main renal artery and follow it to the renal hilum 1 .
The gonadal arteries arise from the abdominal aorta a just inferior to the renal arteries at the level of the second lumbar vertebra. Then they pass inferolaterally under the parietal

Case report
We have encountered an anomalous origin of a left ovarian artery from an inferior renal polar artery during routine educational dissections of the cadavers in the Department of Anatomy, Faculty of Medicine, University of Ruhuna, Sri Lanka.
We observed an accessory renal artery which originates 1 cm above the origin of the left renal artery passing to the inferior pole of the left kidney during dissection of the abdomen of a 70-year-old female cadaver. This artery was identified as the inferior renal polar artery. The artery passes downwards towards the left renal pole crossing the left suprarenal vein, left renal vein, branches of the left renal artery and the left ureter anteriorly. The left ovarian artery was observed to originate from the inferior renal polar artery about 3cm proximal to its entry to the renal substance. Two tributaries of the left renal vein were observed draining blood from the renal hilum and the left ovarian vein was found to be draining to the inferior of the two (Fig 1). Accessory renal arteries to the inferior pole of the kidney crossing anterior to the ureter as in our case, may cause ureteric obstruction leading to hydronephrosis5. Awareness of these variations in the origin of these vessels highlights a potential importance for preprocedural imaging of the vasculature of the renal hilum to avoid complications during the surgery.