Absence of end diastolic frequencies in umbilical artery: A sign of fetal hypoxia and acidosis

In hypoxic fetuses the blood velocity in the aorta is decreased. Doppler measurement of blood velocity is non-invasive but requires expensive pulsed Doppler equipment and an experienced operator. The presence or absence of end diastolic frequencies in the umbilical artery can be ascertained with continuous wave Doppler equipment, which is much cheaper and requires less training of the operator. We examined the relation of the oxygen tension and pH in fetal blood with the absence of end diastolic frequencies in flow velocity waveforms of the umbilical artery.