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 at high risk of pre-eclampsia and/or small-for-gestational-age (SGA) babies attending a maternal-fetal medicine clinic at National Women's Hospital, a 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 > 0.58 was defined as abnormal and an RI of > or = 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 38%, 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 > or = 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 > or = 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.