The current status of Doppler sonography in obstetrics.

Searches for clinical applications of Doppler ultrasound in fetomaternal medicine continue. Currently, there are three main areas of interest: Doppler velocimetry of the umbilical artery, uterine artery and the fetal circulation (cerebral and venous blood flow studies). Evidence from randomized trials suggests that if women with suspected intra-uterine growth retardation or pre-eclampsia are offered Doppler studies of the umbilical artery, a clinically important reduction in perinatal mortality may be expected. On the other hand, screening of low-risk women either by umbilical artery Doppler or uterine artery Doppler is unlikely to be cost-effective. The study of other fetal vessels provides a fascinating insight into vascular changes that occur in fetal compromise, but it is not known whether the use of these tests will actually reduce perinatal mortality and morbidity. None of the Doppler indices used so far, including the middle-cerebral artery to umbilical artery ratio, has been able to match the performance characteristics of umbilical artery Doppler. Until clear evidence emerges on its benefit or otherwise, comprehensive fetal assessment by Doppler ultrasound should be used for research purposes only and results of these tests should not be used to guide clinical practice.