Congenital Absence of the Right Renal vein

A high variation rate exists in the venous anatomy of the kidney. Single or multiple veins are common. Rare anomalies have exclusively been described previously on the left side. We report a case of congenitally absent right renal vein, found by coincidence in assessment of right flank pain. CASE REPORT A 48-year-old female presented emergently with right flank pain without hematuria, with weight loss and chronic faintness. Ultrasonography showed chronic grade II hydronephrosis with dilatation of the right ureter down to the level of the crossing iliac vessels. Resistance index of the right kidney was normal (0.62). Therefore, acute obstruction was unlikely. On contrast enhanced computerized tomography (CT) hydronephrosis and hydroureter were confirmed up to the first sacral vertebra. The right ureter displayed extrinsic obstruction caused by dilated crossing ovarian veins and ovarian masses. Even experienced radiologists could only assume the course of the right renal vein (fig. 1). Three-dimensional CT reconstruction (3DVIEWNIX, Onyx i-Station, Silicon Graphics, Mountain View, California) provided exact assessment of the supposed diagnosis—a single right renal vein was found not to drain into the inferior vena cava, but into a venous varicose complex joined to the right ovarian complex. The venous complex comprised the left ovarian veins and drained regularly into the left renal vein (fig. 2). Duplex sonography demonstrated absence of a right renal vein and confirmed retrograde blood flow to the gonadal venous