Retrocaval ureter is a rare congenital anomaly that occurs is patients almost exclusively on the right side. The usual cause is the persistence of fetal posterior cardinal vein, then the ureter passes posterior to the vena cava and is deviated medially as the vena cava migrates medially to its normal position. This produces the typical S-shaped configuration of retrocaval ureter. Since 1983, when Hochstetter first described this condition. about 200 cases have been reported(8 cases in Korea).

Herein we will report on 2 cases with the brief review of literatures.

Primary non-refluxing, non-obstructed megaureter is a rare condition among the megaureter.

A 11 month old monozygote twin baby had been admitted due to blood and pus tinged spotson a diaper. Although the excretory urogram showed moderately dilated left ureter, but the voiding cystogram and diruetic renogram showed no reflux and no obstruction. So we diagnosed as a primary non-refluxing, non-obstructed megaureter.

We report this case with the review of literatures.