Doppler ultrasound in all three trimesters of pregnancy.

Doppler ultrasound velocimetry of uteroplacental, umbilical, and fetal vessels provides the clinician with important information on the hemodynamics of the vascular area under study. Transvaginal color Doppler is a new technique that allows precise investigation of fetomaternal circulation in early pregnancy. Doppler can be used to follow physiologic hemodynamic changes in uteroplacental and fetal vessels in this period of gestation, and to measure circulatory disturbances in some pathologic conditions. In late pregnancy, Doppler is a useful diagnostic tool for monitoring fetuses with intrauterine growth retardation. Doppler is a better predictor of perinatal morbidity than other methods of fetal surveillance. Recent investigations have shown that fetal vein flow affects fetal wellbeing. Randomized control trials have given different answers about the cost-effectiveness of Doppler in obstetrics.