in general , more common anomalies of renal vein include the left circumaortic renal vein , left retroaortic vein and multiple renal veins . several former studies demonstrated the prevalence and clinical implications of these renal venous anomalies focusing on the left renal vein ( 1 - 3 ) . right renal variations rarely occur due to relatively simple embryological development , as compared to its left counterpart . to the best of our knowledge , multi - detector ct ( mdct ) findings concerning the right circumaortic renal vein have never been reported . we present an extremely rare case with the circumaortic route of the right renal vein and right ectopic kidney . precise awareness of a rare renal venous variation is important for accurate diagnosis in the staging of urologic cancers and helps prevent unforeseen complications during operations or interventional procedures . a 42-year - old man underwent abdominopelvic mdct due to the evaluation for traumatic splenic rupture . ct examination was performed using a 128-detector - row ct scanner ( definition as+ , siemens medical solutions , forchheim , germany ) . helical scan data was acquired using 32  1.2 mm collimation , a rotation speed of 0.5 sec , pitch of 0.6 , and 120 kvp . attenuation - based tube current modulation was used with a reference tube current - time product set at 210 mas per rotation . volume rendering images were obtained by using aquarius intuition viewer ( terarecon , sanmateo , ca , usa ) . the right ectopic kidney was located between the level of the 3rd lumbar vertebral body superiorly and 5th lumbar vertebral body inferiorly . the right ectopic kidney was incompletely rotated while the hilum and renal pelvis were facing anterior to the parenchyma . the anterior portion of the right renal vein which was emerging from the anterior part of the ectopic kidney crossed to the left side of the aorta with a ventral course to the inferior vena cava ( ivc ) and aorta ( fig . then , it turned around and coursed dorsally to the aorta and finally drained into the ivc ( fig . the right renal artery arose from the abdominal aorta as the upper polar artery ( fig . the patient showed american association for the surgery of trauma splenic injury grade 2 and stable vital signs , so conservative treatment was performed . the development of the renal vein is closely related with the embryogenesis of the ivc ( 1 , 2 ) . the ivc is formed from three parallel veins that subsequently appear and regress ( fig . in order of appearance , they are the posterior cardinal veins , the subcardinal veins and the supracardinal veins . first , the posterior cardinal veins develop and receive blood returning from the body below the heart . lastly , the supracardinal veins develop , and it lies in a plane dorsal to the aorta . the subcardinal veins and the supracardinal veins are interconnected by a network of veins , forming a venous collar around the aorta . two renal veins form as ventral and dorsal ; the dorsal vein usually degenerates , the ventral vein forms the renal vein . various anomalies of the renal vein can develop during the developmental process ( 3 ) . the most common anomaly is the circumaortic left renal vein , which results from persistence of the dorsal vein and intersupracardinal anastomosis . another common anomaly is a retroaortic left renal vein , which has a prevalence of 2.7% . as with a circumaortic left renal vein , a retroaortic left renal vein results from persistence of the dorsal arch of the renal collar . however , in this variation , the intersubcardinal anastomosis and ventral vein regress so that a single renal vein passes posterior to the aorta . in contrast to the left circumaortic and retroaortic vein , abnormal course of the right renal vein is extremely rare ( 4 ) . the development of the left renal vein is more complex than its right counterpart . in our case , the circumaortic route of the right renal vein was formed by the persistence of the intersubcardinal anastomosis , left suprasubcardinal anastomosis and the intersupracardinal anastomosis ( fig . the intersubcardinal anastomosis formed the ventral arch of the right circumaortic renal vein , while the intersupracardinal anastomosis formed the dorsal arch . the left suprasubcardinal anastomosis connected between the ventral and dorsal arch at the left paraaortic area . anomalies of renal vessels are particularly frequent in kidneys that do not ascend or rotate normally . besides the circumaortic and retroaortic renal veins , there are supernumerary veins , double renal vessels and accessory renal vessels related to ectopic kidneys that have been reported . since anomalous venous structures tend to be dilated and tortuous , causing injury more easily , lack of preoperative recognition of renal vein anomalies can have potentially disastrous consequences ( 6 ) . the relationship of the ureter to the vessel in the retroperitoneum may also be confusing . control of the proximal aorta may be difficult to achieve in patients with circumaortic collars . during removal of donor kidneys or urological procedures , it is also important for radiologists to interpret angiograms or staging for lymph node evaluation ( 6 ) . the right circumaortic renal vein is seen in the left retroperitoneal space , so surgeons may misconceive it as the left renal vein .
anomalies of renal vasculature combined with ectopic kidneys were found on a multi - detector ct scan . 
 knowledge of renal vascular variation is very important for surgical exploration , radiologic intervention and staging for urologic cancer . 
 we present an extremely rare case of a right circumaortic renal vein combined with a right ectopic kidney . 
 the right kidney was located at the level between the third and fifth lumbar vertebra . 
 the right circumaortic renal vein crossed the aorta and returned to the inferior vena cava behind the aorta .