Ureteropelvic junction stenosis: antenatal ultrasonographic diagnosis, postnatal investigation, and follow-up.

Between January 1981 and October 1984, the diagnosis of ureteropelvic junction (UPJ) stenosis was suspected in 39 fetuses after routine obstetrical ultrasound (US) examination. Postnatal investigation revealed that the initial diagnosis had been accurate in 30 cases (77%). There were 35 UPJ stenoses in 30 patients. The degree of dilatation of the renal pelvis (grades III, IV, or V) observed postnatally with sonography as well as the obstructive excretory pattern noted by renal isotope scanning were used as criteria to determine the need for early postnatal pyeloplasty (performed in 25 patients), which relieved the obstruction and, in the majority of patients, improved renal structure and function.