A RANDOMIZED CONTROLLED TRIAL OF ASPIRIN IN PATIENTS WITH ABNORMAL UTERINE ARTERY BLOOD-FLOW

Objective: To evaluate color Doppler imaging of the uterine arteries a s a screening test in nulliparous women, and to examine the role of lo w-dose aspirin therapy in pregnancies with abnormal uteroplacental res istance. Methods: At the routine 18-week fetal morphology ultrasound s can, 955 nulliparous women underwent color Doppler imaging of the uter ine arteries. Abnormal uteroplacental vascular resistance was defined with respect to both the systolic-diastolic ratio of the now velocity waveform and the presence of an ipsilateral early diastolic notch. Tho se with abnormal uterine artery waveforms were asked to participate in a randomized controlled trial of aspirin therapy. Pregnancy outcomes were compared in women with normal or abnormal flow velocity waveforms , as well as in the two arms of the intervention study. Results: Of 18 6 women with abnormal uteroplacental resistance according to criteria defined previously, 102 agreed to randomization to either low-dose asp irin (100 mg/day) or placebo for the remainder of the pregnancy. Abnor mal uterine artery now velocity waveforms were associated with statist ically significant increases in preeclampsia (11 versus 4%), birth wei ght below the tenth percentile (28 versus 11%), and adverse pregnancy outcome (45 versus 28%). Prophylactic aspirin therapy did not result i n a significant reduction in pregnancy complications. Conclusion: Abno rmal uteroplacental resistance at 18 weeks' gestation was associated w ith a significant increase in adverse pregnancy outcome. Low-dose aspi rin did not reduce pregnancy complications in women with uteroplacenta l insufficiency.