Abstract: Objective  To investigate the value of color Doppler ultrasound in the determination of interlobular artery resistance index and evaluation of renal function in children with hydronephrosis. 
Methods  Fifty-eight children with hydronephrosis were selected as case group, in the same period, 70 healthy children as control group, Color Doppler ultrasonography was used to measure the pulsatility index(PI) of interleaf renal artery in 2 groups PI, resistance index(RI), maximum systolic blood flow velocity(Vmax); and Vmax and minimum diastolic blood flow velocity(Vmin). The arterial resistance index ratio(RIR), RIR=RI/contralateral RI were calculated. Glomerular filtration rate of the affected kidney by dynamic renal radionuclide imaging glomerular filtration rate（GFR) was determinated. The correlation between renal ultrasound index and GFR in case group was analyzed. 
Results  The values of PI and RI in the healthy kidney of the children with unilateral hydronephrosis were significantly lower than those in the control group, while the values of PI and RI in the affected kidney of the children with unilateral hydronephrosis were significantly higher than those in the control group and the healthy kidney of the children with unilateral hydronephrosis,the difference was statistically significant(P＜0.05). Comparison of RIR between case group and control group, difference was statistically significant(P＜0.05). And with the increase of hydronephrosis, the RIR of children with IV degree hydronephrosis decreased, difference was statistically significant(P＜0.05). Forty-eight patients with unilateral hydronephrosis had lower renal GFR than healthy patients, difference was statistically significant(P＜0.01). There was no correlation between renal PI and GFR(r=0.071, P=0.574); Low correlation between RI and GFR(r=0.506, P=0.041). RIR had a moderate correlation with GFR(r=0.731, P=0.026). 
Conclusion  RIR is related to the degree of hydronephrosis, and it is less affected by age factors. Color Doppler ultrasound can indirectly evaluate the renal function of children with hydronephrosis RIR, It can be used as the first choice to evaluate renal function in children with hydronephrosis.

Key words: hydronephrosis, glomerular filtration rate, ultrasound, Doppler, color