The aim of the study was to investigate the short-term effects of low-dose aspirin treatment on uterine artery Doppler in pregnancies that were high-risk for preeclampsia. This prospective observational study included 82 patients with singleton pregnancies between 11-14 weeks of gestation. Uterine artery Doppler measurements were obtained by transvaginal ultrasonography at the first prenatal visit of women who started low-dose aspirin treatment due to the high risk of preeclampsia and women who did not receive low-dose aspirin. Uterine artery Doppler measurements of both groups were repeated 7-10 days after the first examination. There was a significant decrease in the presence of uterine artery diastolic notch in the low-dose aspirin group (p < .001). In both groups, the mean uterine artery PI values between the two exams tended to decrease, but the decrease in the control group was the only significant decrease (p = .014). The changes in Doppler indices were more pronounced in the control group. Therefore, they are much more likely to be related to the increase in gestational age than with the use of aspirin. Although there was an improvement in uterine arteries of Doppler measurements in high-risk women, they still had a high resistant flow compared to women with normal pregnancies. IMPACT STATEMENTWhat is already known on this subject? Pregnant women at high risk of preeclampsia have increased uterine artery resistance. Low-dose aspirin therapy is the only strategy to prevent the development of preeclampsia in these patients.What do the results of this study add? Low-dose aspirin therapy may improve uterine perfusion in the short term. After treatment, uterine artery resistance remains higher than in normal pregnancies.What are the implications of these findings for clinical practice and/or further research? Since baseline uterine blood flow and changes throughout pregnancy can be very different depending on the risk of preeclampsia, aspirin-treated or untreated groups may be used to evaluate the efficacy of aspirin in future studies. For example, patients with 11 weeks and 13 weeks of gestation can be divided into aspirin treated and control groups and efficacy of starting the aspirin treatment at 11 weeks of gestation vs 13 weeks of gestation can be evaluated.
Keywords: First trimester; low-dose aspirin; preeclampsia; uterine artery Doppler.