Ultrasonic evaluation of the obstructed duplex kidney.

The problem of a duplex collecting system associated with an obstructed ectopic ureter or ureterocele is common in pediatric urology. Four such patients were studied by gray scale ultrasound which was useful in demonstrating the dilated upper pole collecting system as well as an ectopic ureter and a ureterocele. Although the diagnosis of a nonfunctioning upper pole unit in a duplex kidney is usually suggested by the urogram, ultrasound provides a noninvasive means of confirmation which is independant of function. Further, ultrasound-guided puncture with antegrade pyelography demonstrates the course of the ectopic ureter, thus providing a more complete preoperative evaluation.