The evaluation of Doppler indices in renal vessels in normal fetuses and in fetuses with obstructive uropathy

Abstract

Purpose: The aim of the study was an evaluation of Doppler indices in renal vessels in normal fetuses and in fetuses with diagnosed obstructive uropathy.Methods: In the study, there were included 106 normal fetuses and 21 fetuses with signs of the obstructive uropathy. In pregnancies complicated by the uropathy, the measurements of Doppler flow in renal arteries were performed twice: in the ahydramnion settings and after the diagnostic amnioinfusion. The analyzed indices included the pulsatility index and the resistance index.Results: The diagnosis of uropathy was set‐up at the mean gestational age of 20.3 ± 2.0 weeks. The control group consisted of 106 healthy fetuses from normal pregnancies at the mean gestational age (28 weeks). The physiological absence of an end‐diastolic flow in renal arteries was found in normal pregnancies and that parameter was excluded from further analysis. The PI values in normal pregnancies decreased with the gestational age from the mean value of 3.16 at 15 weeks to 2.19 at 40 weeks of gestation. In pregnancies at gestational age below 26 weeks complicated by the uropathy, the PI was significantly lower with the mean value of 1.57. However, there were no statistical difference in PI values for pregnancies above 30 weeks of gestation, the mean values of PI were 2.39 and 2.33 for normal and pathological pregnancies, respectively. There were also no differences for PI values among pregnancies with the uropathy before and after amnioinfusion.Conclusions: There is a physiological linear decrease in the PI values in fetal renal arteries with the gestational age. The RI cannot be used for the evaluation of renal function due to the physiological absence of an end‐diastolic flow in renal arteries. The PI was significantly lower in pregnancies complicated by obstructive uropathy at the gestational age below 26 weeks.