Retroaortic left renal vein: a clinically significant vascular variation with suggestion of a practical typological scheme

The retroaortic left renal vein (RLRV) is a rare vascular variant with a typical position of the vein between the abdominal aorta and the vertebral column. Despite usually asymptomatic, RLRV might be associated with posterior nutcracker syndrome, other vascular pathologies and may cause major surgical complications. An existing but not expected RLRV might hamper aortic surgical dissection and to cause a life threatening bleeding. A case of a RLRV was observed during routine dissection of a formalin fixed 62-year-old female cadaver. The left kidney was found to be ectopic and located lower than usual between the level of L1 and L4 vertebra. The left renal vein was formed in the renal hilum at the level of L2/L3 intervertebral disc, and then passed obliquely downwards behind the abdominal aorta to join in the inferior vena cava at the level of upper border of L4 vertebra. The length of the RLRV was 7.5 cm. The main tributaries were the left suprarenal and left ovarian veins. Measuring the diameters of the renal vein showed slight dilation at its origin. Based on the literature review, the vascular variation reported here can be classified as Type II – RLRV draining at a lower than normal level of the inferior vena cava. An extended classification scheme of the left renal vein variations is presented here as well as an optional typological scheme.