Renal duplex Doppler ultrasound: an adjunct in the evaluation of hydronephrosis in the child.

We used renal duplex Doppler ultrasound to evaluate 28 hydronephrotic pediatric kidneys. A total of 28 normal renal units was used as controls. Renal Doppler ultrasound findings were compared with drainage values obtained with renal scintigraphic diuretic renography, and demonstrated close correlation. In control units significantly different resistive index values were noted between patients 0 to 12 months old and those older than 1 year. The younger group had average resistive indexes of 0.66, while the older group had an average value of 0.57 (p < 0.001). In hydronephrotic kidneys resistive index values were significantly higher (0.83) in renal units with obstructive T1/2 values on diuretic renography compared to those with indeterminate or nonobstructive T1/2 values (0.63) (p < 0.001). Renal Doppler ultrasound correlates closely with diuretic renography in hydronephrotic systems in infants and in older children. Additionally, it provides an early, noninvasive modality of assessing the dilated upper tract in infants and older children. Therefore, renal Doppler ultrasound is a reliable adjunct in identifying obstructed renal units.