Randomised controlled trial of Doppler ultrasound screening of placental perfusion during pregnancy.

We have done a randomised controlled trial to assess the effect on primary management and outcome of routine doppler ultrasound examinations of the umbilical and uterine arteries during pregnancy. Over 9 months, 2600 women with singleton pregnancies were recruited from a general obstetric population. Of 2475 women who delivered in hospital after 20 weeks' gestation, 1246 had been allocated at random to receive standard antenatal care with routine doppler examinations. The first doppler ultrasound was done at 19-22 weeks' gestation, and thereafter examinations were monthly if the pregnancy was considered high risk (192) or once at 32 weeks if considered low risk (1054). The control group of 1229 women received standard, antenatal care without doppler ultrasonography. The study groups did not differ in number of antenatal admissions or cardiotocographs, gestational age at delivery, method of delivery, frequency of deliveries with fetal distress, or need for resuscitation or admission to the neonatal intensive care unit. More perinatal deaths occurred in the doppler group (17 vs 7, relative risk 2.4, 95% Cl 1.00-5.76), but only 1 of 11 normally formed stillbirths and none of the 4 normally formed neonatal deaths after 24 weeks' gestation had an abnormal umbilical-artery doppler examination. We did not demonstrate any improvement in neonatal outcome by routine doppler ultrasound screening of a general obstetric population.