Quantitative measurement of fetal blood flow using Doppler ultrasound.

Blood flow in the descending human fetal aorta and in the intra-abdominal portion of the umbilical vein was quantified using pulsed Doppler ultrasound in a longitudinal series of normal pregnancies, the accuracy of the method having been verified in vitro. The results obtained are in keeping with previous studies but indicate that, although the method is relatively simple, determination of absolute blood flow in these vessels has little clinical potential because of inherent measurement inaccuracies.