Screening with a uterine Doppler in low risk pregnant women followed by low dose aspirin in women with abnormal results: a multicenter randomised controlled trial.

OBJECTIVES: To assess whether systematic screening with an uterine artery Doppler in low risk pregnant women followed by the prescription of low dose aspirin in cases with abnormal results reduced the incidence of intrauterine growth restriction and pre-eclampsia.

DESIGN: A multicentre randomised trial.

POPULATION: 3,317 low risk pregnant women. In the Doppler group, the uterine artery Doppler was performed between 20 and 24 weeks. Women with abnormal results received 100 mg of aspirin daily until the 35th week.

MAIN OUTCOME MEASURES: Intrauterine growth restriction was defined as birthweight below the tenth and the third centile according to gestational age. Pre-eclampsia was defined as hypertension associated with proteinuria > 0.5g/L.

RESULTS: Intrauterine growth restriction, whether defined by the third or tenth centile, did not differ significantly between the two groups (RR = 1.22 [0.73 - 2.04] and 1.18 [0.93 - 1.51] respectively). Screening with uterine artery Doppler did not affect birthweight or any of the criteria of perinatal morbidity. There was no effect on the incidence of pre-eclampsia (RR = 1.99 [0.97 - 4.09]) or hypertensive disorders. These results were the same for nulliparae and multiparae.

CONCLUSIONS: There is no justification for screening with uterine artery Doppler in a low risk population, even if abnormal results are followed by aspirin treatment and increased prenatal surveillance. Future studies must assess predictive tests that can be performed early in pregnancy and can identify populations at very high risk of pre-eclampsia and intrauterine growth restriction. Only when all of these conditions are fulfilled, aspirin or other treatments may prove its efficacy.