Doppler velocimetry of the uterine arteries in nulliparous women.

The aim of this study was to evaluate the role of uterine artery Doppler velocimetry performed at 20 and 24 weeks gestation in predicting gestational hypertension and small-for-gestational age babies in a population of nulliparous women. Four hundred and fifty-six patients without risk factors for pregnancy complications and with fetuses free from structural abnormalities at ultrasonographic examination at 20 weeks gestation were considered in the study. During the routine 20 weeks ultrasound a continuous-wave Doppler examination of the uterine arteries was performed. The patients with abnormal uterine Resistance Index (RI) repeated the Doppler evaluation at 24 weeks by means of Colour Doppler equipment. Among the 419 women who completed the study an abnormal Doppler uterine arteries velocimetry was found in 8.6% of the patients. Pregnancy complications (gestational hypertension and/or small-for-gestational age babies) were observed in 56% of the patients presenting high uteroplacental RI versus 10% of those with normal uterine artery velocimetry (P = 0.0001). In the group of patients with an abnormal RI value, the presence of a diastolic notch in one or both of the uterine arteries identified a population of pregnant women at higher risk for pregnancy complications when compared with patients without notch (78% vs. 33%, P = 0.007). The knowledge of the uteroplacental resistance can help in identifying a subgroup of patients at higher risk of hypertensive disorders and small-for-gestational age babies that could benefit from prophylaxis with low dose aspirin.