The use of umbilical artery Doppler ultrasonography in modern obstetrics.

In contrast to the reduction in perinatal mortality in high-risk pregnancies, screening of low-risk pregnancies with umbilical artery Doppler ultrasonography has shown no benefit. Advances in pathophysiology question the assumption that the placenta is hypoxic in fetal growth restriction, with absent end-diastolic frequencies in the umbilical artery. The timing of delivery in relation to Doppler findings is uncertain, and so trials that relate Doppler findings to neurodevelopmental outcome are necessary to refine the role of this technique in obstetric practice.