Outcome of prenatally diagnosed fetal hydronephrosis

To demonstrate the postnatal investigation, treatment and outcome of infants with hydronephrosis prenatally diagnosed by ultrasound between 1994 and 1996.

In a two-year period we studied 20 infants who presented with hydronephrosis diagnosed by prenatal ultrasound and confirmed by postnatal ultrasound. Unilateral hydronephrosis was diagnosed in 17 infants and bilateral hydronephrosis in 3. An anteroposterior renal pelvic diameter > 7 mm after 33 weeks of pregnancy was used to predict abnormal outcomes. In the postnatal follow-up period, the infants were followed with sequential ultrasound and urinalysis. 99mTc-diethylene triamine pentaacetic acid scan, intravenous pyelography and voiding cystourethrography were performed in selected cases. Pyeloplasty was performed only if there was evidence of renal compromise.

A male predilection was found. The left kidney was more commonly involved. Ultrasonic follow-up of the 20 infants showed that hydronephrosis resolved in 9, who were all in the unilateral hydronephrosis group. The range of fetal renal pelves on prenatal ultrasound was 7-15 mm in the resolution group. Pyeloplasty was performed in three unilateral hydronephrosis infants. Follow-up ranged from 36 to 72 months.

When the fetal renal pelvis was < 15 mm on prenatal ultrasound, it never progressed. Prenatally diagnosed hydronephrosis may be safely observed, and surgical correction should be performed only if renal compromise occurs.