Objectives: To establish reference values for the first-trimester uterine artery (UtA) pulsatility index (PI) and to investigate the role of UtA Doppler in the early prediction of hypertensive disorders and their associated complications in an unselected Mediterranean population.
Methods: A prospective study including 1091 consecutive singleton pregnancies undergoing routine early ultrasound screening at 11-14 weeks of gestation was performed. The left and right UtA were examined by color and pulsed Doppler transvaginally. The mean PI and the presence of bilateral protodiastolic notching were cross-sectionally recorded. Reference ranges were calculated and the pregnancies were followed for occurrence of pre-eclampsia, gestational hypertension, intrauterine growth restriction, placental abruption and stillbirth. The sensitivity and predictive values of a mean UtA-PI>95th percentile and the presence of bilateral notching in the prediction of these pregnancy complications were calculated.
Results: A total of 999 women were finally included. Both the mean UtA-PI and the prevalence of bilateral notches showed a significant linear decrease between 11 and 14 weeks' gestation. Sixty-seven (6.7%) pregnancies developed at least one of the formerly described complications, including 22 (2.2%) cases of pre-eclampsia and 37 (3.7%) cases with intrauterine growth restriction. Compared with women with a normal outcome, complicated pregnancies showed a significantly higher mean PI (2.04 vs. 1.75; P<0.05, t-test) and a higher prevalence of bilateral notching (58% vs. 41%; P<0.05, Chi-square test). Using the 95th percentile in mean UtA-PI as a cut-off, 23.9% (95% CI, 13.7-34.1) of complicated pregnancies and 30.8% (95% CI, 5.68-55.85) of severe cases were identified.
Conclusions: Our results suggest that pregnancies with an increased risk of developing hypertensive disorders and related complications already have an abnormally increased UtA-PI in early pregnancy. However, the use of a single uterine Doppler measurement for screening purposes in unselected early pregnancy populations has limited clinical value. The use of UtA-PI combined with other screening tests needs to be determined by further investigation.
Copyright (c) 2005 ISUOG.