Mid-trimester uterine artery Doppler screening as a predictor of adverse pregnancy outcome in high-risk women

Objective To assess the value of uterine artery Doppler ultrasound screening, when performed in a clinical setting, to predict complications of impaired uteroplacental blood flow in high-risk women. Design A prospective audit. Subjects A total of 116 pregnancies in 114 women aat high risk of pre-eclampsia and/or small-for-gestational-age (SGA) babies attending a maternal-fetal medicine clinic at National Women's Hospital, tertiary referral hospital, Auckland, New Zealand. Methods Uterine artery Doppler screening was performed as part of clinical practice between 22 and 24 weeks' gestation. A resistance index (RI) was calculated from each uterine artery and the presence or absence of a notch was determined. An RI of greater than or equal to 0.7 was defined as very abnormal. The main outcome measures were: pre-eclampsia, SGA baby (birth weight < 10th centile), placental abruption, intrauterine death, 'all' and 'severe' outcomes. Results Thirty-two (27.5%) women developed pre-eclampsia, 31 (26.7%) had SGA babies, 23 (20%) were delivered at <34 weeks because of pregnancy complications, and there were three (2.6%) placental abruptions and three (2.6%) perinatal deaths. The sensitivity of any RI of > 0.58 for pre-eclampsia, SGA, 'all' outcomes and 'severe' outcome was 91%, 84%, 83% and 90%, respectively. The specificity of any RI of > 0.58 for these outcomes was 42%, 39%, 47% and 28%, respectively. The positive predictive value of any RI of > 0.58 for the same outcomes was 37%, 33%, 58% and 24%, respectively. Among women with both RI values of greater than or equal to 0.7, 58%, 67%, 85% and 58% developed pre-eclampsia, SGA, 'all' and 'severe' outcomes, respectively. In women with bilateral notches, 47%, 53%, 76% and 65% developed the respective outcomes. Women with both RI values of greater than or equal to 0.7 and women with bilateral notches had relative risks of 11.1 (95% CI 2.6-46.4) and 12.7 (95% CI 4.0-40.4) for developing severe outcome, respectively. Only 5% of women with both RI values of < 0.58 developed a severe outcome. Conclusion In high-risk women, uterine artery Doppler waveform analysis performed best in the prediction of severe adverse outcome and was better than clinical risk assessment in the prediction of pre-eclampsia and SGA babies. Further studies are necessary to determine how information from uterine artery Doppler studies should modify current practice in high-risk women.