Fetal hydronephrosis and renal artery blood velocity.

The renal artery blood velocity waveform was recorded by Doppler ultrasound in 17 fetuses with hydronephrosis in the third trimester of pregnancy. The waveform was analyzed for pulsatility index and related to the degree of dilatation of the renal pelvis. The pulsatility index was found to be above the renal reference range in only five out of the total of 31 kidneys examined. No relationship was found between the degree of dilatation and pulsatility index. A slight relationship was, however, found between abnormal pulsatility index and the need for operative intervention in the neonatal period. Doppler ultrasound is a valuable tool for evaluating renal circulation, but the results suggest limited clinical value in fetuses with hydronephrosis.