8/11/2023 0 Comments Umbilical artery doppler![]() In conditions such as preeclampsia and fetal growth restriction abnormal uterine artery Doppler studies indicate inadequate placentation and have been correlated with histological evidence of defective replacement of spiral arteries by maternal trophoblast. Uterine artery Doppler studies reflect the resistance in the utero-placental circulation and have not been proven to reduce perinatal morbidity or mortality. These fetuses have a very low risk of antenatal fetal compromise, have a low perinatal mortality, and do not normally require preterm delivery. The likely reason for the reduced perinatal mortality is that the abnormal Doppler waveform highlights the at risk fetus who is then subject to more frequent surveillance ultimately resulting in timely preterm delivery.Ībout two thirds of small gestational age fetuses have normal umbilical artery Doppler studies and are unlikely to have histologic evidence of abnormal placental vascular development. Umbilical artery Doppler studies have been well evaluated in randomised controlled trials and use of umbilical artery Doppler studies in small for gestation age pregnancies and in pregnancies with the preeclampsia is associated with a 30% reduction in perinatal mortality (Cochrane Library 2000). Current data is conflicting regarding the utility of umbilical arterial (UA) Doppler assessment as a predictor of adverse perinatal outcomes in. In many instances, fetuses with absent end-diastolic velocity would present much earlier in pregnancy and may require extremely preterm delivery. However, most obstetricians would consider delivering a fetus with absent end-diastolic velocity from about thirty two weeks gestation following administration of corticosteroids. Abnormal umbilical Doppler waveforms can be present for weeks before there is evidence of fetal compromise and therefore are a marker of a high risk situation and should not normally be used in isolation as an indication for delivery. In pregnancies with reduced, absent or reversed end-diastolic velocity, there is an increased risk of stillbirth, asphyxia, chromosomal and congenital abnormality. These abnormal waveforms are associated with histological evidence of reduced numbers of small placental blood vessels and therefore reflect "placental insufficiency". Figure 2: Umbilical Doppler waveforms in healthy pregnancy and in pregnancies with fetal growth restriction. ![]()
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