Doppler investigation of uteroplacental blood flow resistance in the second trimester: a screening study for pre-eclampsia and intrauterine growth retardation.

OBJECTIVE: To assess the screening properties of a mid-trimester uteroplacental Doppler scan in a normal unselected population.
DESIGN: A cross-sectional study measuring an averaged resistance index (AVRI) from four sites (left and right uterine and arcuate arteries) with continuous wave Doppler ultrasound.
SETTING: Routine booking ultrasound, King's College Hospital, London.
SUBJECTS: 977 women at 16-24 weeks gestation. MAIN OUTCOME MEASURES: Intrauterine death, birthweight, pregnancy-induced hypertension (PIH), antepartum haemorrhage.
RESULTS: There was a 96.5% follow-up. Pregnancies with high AVRI values had a higher prevalence of proteinuric hypertension, placental abruption, small-for-gestational-age babies, and fetal loss. When AVRI was greater than 95th centile, the overall risk of pregnancy complications was 67%, and the risk of a severe complication was 25%. However, the sensitivity of the test for these complications was only 13% and 21% respectively. The risk for an individual woman with a high AVRI of developing a complication was increased by up to 9.8 times.
CONCLUSION: Although Doppler screening does detect a unifying defect leading to perinatal death, pre-eclampsia, growth retardation and placental abruption, the predictive values do not yet justify its introduction as a routine test.