Fetal Renal Artery and Umbilical Artery Doppler Flow and Fetal Urine Output

ABSTRACT

The object of this study was to determine if a correlation exists between the resistance index (Rl) of the umbilical artery, the Rl of the fetal renal artery, and hourly urine output by fetuses of normal pregnancies. Doppler flow study of the fetal renal artery and the umbilical artery was performed in 110 fetuses between 19 and 40 weeks' gestation. Color and pulse wave Doppler was used to obtain the flow velocity waveforms. The Rl of the flow velocity waveforms was calculated. Fetal bladder volume was calculated by transverse, anteroposterior, and longitudinal diameters obtained from coronal and transverse sonographic images of the fetal urinary bladder. The difference in bladder volume at 30-minute intervals was used to determine hourly urine output. Gestational age has a positive linear association with fetal urine output (P >0.01). The Rl of the fetal renal artery has a negative linear association with gestational age (P > 0.05). The Rl of the umbilical artery decreased with an increase in gestation age (P >0.01). There was a significant correlation between the Rl of the umbilical artery (P >0.01) and the fetal renal artery (P >0.05) and hourly urine output by the fetus. The Rl of the fetal renal artery decreased with gestational age. Hourly urine output of the fetus increased with gestational age. The Rl of the umbilical artery and the fetal renal artery had a significant correlation with fetal urine output.

Keywords

Doppler ultrasound - fetal renal artery - umbilical artery - fetal urine production