Abnormal umbilical artery doppler waveform during pregnancy Absent end-diastolic umbilical artery flow 2022-04-10T13:42:38Z An anomaly that is visualized by umbilical artery Doppler velocimetry. Flow in the umbilical artery should be in the forward direction in normal circumstances. This anomaly is characterized by an absence of flow in the umbilical artery at the end of diastole. Abnormal umbilical artery Doppler velocimetry is correlated with a pathologic lesion of the placenta characterized by obliteration of arterioles in the tertiary stem villi; the umbilical artery flow velocity waveform is primarily determined by placental villous vascular architecture. The increased placental vascular resistance is reflected as a decreased diastolic phase of the umbilical artery waveform