A 2-year-old girl suffering from congenital mid-ureter stenosis due to an aberrant vessel underwent division of the vessel and Y-V plasty of the ureter. The vessel originated from the mesoureter suggests that the vessel had been a remnant of temporary renal artery which appeared during the cranial migration of the metanephros in fetal life. Histology of the stenotic portion of the ureter revealed almost normal muscular development, suggesting that the compression of the ureter by the vessel occurred comparatively late in fetal life. The patient required resection of the plastied ureter portion and end-to-end anastmosis because of suture insufficiency. The course after the reoperation was uneventful. In this paper, a rare case of congenital mid-ureter stenosis was reported and the cause of ureteral stenosis associated with an aberrant vessel was discussed.
