Umbilical artery blood flow velocity waveforms and associations with fetal abnormality

Blood flow velocity waveforms from the umbilical artery of 126 normal fetuses with no evident complications at 20-42 weeks of gestation and 15 fetuses with various abnormalities at 25-42 weeks were recorded using pulsed Doppler ultrasound. The resistance index (RI) was assessed on each blood flow velocity waveform. In 9 fetuses with a slight abnormality, the values of RI were within the mean +/- 2 SD of normal fetuses, and the outcome was good. In 3 of 6 fetuses with a serious abnormality, the values of the RI were high, and 2 of these fetuses died in utero within a few days after the recording. Another fetus with a high RI and 3 with a normal RI died neonatally. Therefore, Doppler ultrasound assessments of the umbilical artery blood flow velocity waveform in utero aid in predicting the outcome for fetuses with major abnormalities.