THE PREDICTIVE VALUE OF UMBILICAL ARTERY DOPPLER STUDIES FOR PREECLAMPSIA OR FETAL GROWTH-RETARDATION IN A PREECLAMPSIA PREVENTION TRIAL

Objective: To determine the clinical utility of longitudinal Doppler u mbilical artery systolic-diastolic ratios (S/D) to predict the occurre nce of either preeclampsia or fetal growth retardation (FGR) in a low- risk population. Methods: Healthy nulliparas with singleton gestations were enrolled in a double-blind trial of low-dose (60 mg) aspirin for preeclampsia prevention. Treatment was initiated at 24 weeks and cont inued until delivery. Continuous-wave Doppler studies were scheduled b efore assignment to treatment and at 27-31, 32-36, and 37-42 weeks. Pr eeclampsia was defined as a persistent diastolic blood pressure of at least 90 mmHg with proteinuria, and FGR was defined as birth weight be low the tenth percentile. Doppler values were considered abnormal if t hey exceeded the 90th percentile for the gestational age range in the study population. Summary predictive values were computed for the abno rmal S/D at each gestational age interval. To assess the potential eff ect of the administration of low-dose aspirin, logistic regression was used to model the relation between the Doppler indices, aspirin use, and these abnormal pregnancy outcomes. Results: A total of 1665 Dopple r examinations were performed on 565 women. Forty-four fetuses develop ed FGR and 21 women were diagnosed with preeclampsia. The positive pre dictive values of an abnormal S/D for the subsequent development of FG R were 13-17% across the gestational age ranges studied, and the posit ive predictive values for preeclampsia were 0-5%. Aspirin treatment di d not affect the relation between the Doppler indices and these outcom es in the logistic regression model. Conclusion: Elevated umbilical ar tery S/D is not a clinically useful predictor of either FGR or preecla mpsia in a low-risk population.