First Trimester Uterine Artery Doppler Screening for Preeclampsia

Background: Several screening strategies have been proposed to identify patients in early pregnancy at increased risk of preeclampsia who may benefit from low dose aspirin (LDA) to reduce their risk. One approach is risk-stratification based on patient-level risk factors that can be identified in the first trimester without assessment of biomarkers. This risk factor-based approach is the preferred approach in the US, with low dose aspirin 81 mg daily advised for those with identified risk factors prior to 16 weeks of gestation [Recommendation supported by American College of Obstetricians and Gynecologists (ACOG), Society of Maternal-Fetal Medicine (SMFM) and United States Preventive Services Task Force (USPSTF); ACOG committee opinion #743]. In 2017 the Aspirin for Evidence-Based Preeclampsia Prevention (ASPRE) trial reported results utilizing a screening algorithm including first-trimester serum markers, such as placental growth factor and pregnancy-associated plasma protein-A, as well as uterine artery Doppler to identify high-risk patients. Subsequently, societies such as the Fetal Medicine Foundation (FMF) and International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) endorsed a screening algorithm including serum and ultrasound biomarkers. As these laboratory screens have limited availability in the US, this combined screening approach utilizing serum and ultrasound-based biomarkers has not been adopted widely in the US. Further, the efficacy of utilizing uterine artery Doppler alone as an independent biomarker approach to identify preeclampsia risk is unclear. Objective: To quantify the impact of utilizing first trimester uterine artery Doppler as a screening approach to identify patients at risk of preeclampsia. Study Design: At the study institution, all patients underwent first trimester ultrasound at 11-14 weeks, which included uterine artery Doppler (utAD) as a preeclampsia screening approach. Mean pulsatility index of >90th percentile identified those at high-risk, and they were advised to consider LDA for preeclampsia prevention. Medical records were reviewed over one year, 4/1/2024-3/31/2025, to ascertain the proportion of those with abnormal utAD who received LDA (compliance). We performed a retrospective cohort study quantifying the proportion of those with abnormal utAD (U/S strategy) who would have been identified based on the ACOG recommended risk-factor based strategy (RF strategy). Based on these factors, the resultant number of patients identified by U/S strategy and cases of preeclampsia prevented utilizing U/S strategy over RF strategy were estimated. Results: During the study period, a total of 2,426 patients underwent utAD screening during the first trimester. Of those, 221 (9.1%) had abnormal utAD. Of those with abnormal utAD, 153/221 (69%) received LDA and 68/172 (31%) did not, despite LDA being recommended in nearly all cases. Over two-thirds of those with abnormal utAD, 156/221 (71%) had indications for LDA based on RF strategy, and would have been identified as at-risk without undergoing utAD. Of those, over three-quarters, 118/156 (76.3%), received LDA. Just over one quarter, 65/221 (29%), screened positive by U/S strategy (abnormal utAD) alone, and would not have screened positive based on RF strategy. Of those who screened positive by U/S strategy alone, only 35/65 (54%) received LDA. In summary, use of a first trimester U/S screening approach rather than RF approach identified only an additional 35/2426 (1.4%) patients per year who received LDA. Using assumptions from prior published studies that 4.3% of high-risk patients who screen positive with utAD and do not receive LDA will develop preeclampsia, 1.5 of the 35 patients identified by U/S screening alone in our cohort would go on to develop preeclampsia if LDA was not given. Assuming that LDA results in as high as 62% reduction in preeclampsia risk, less than one case of preeclampsia per year would be prevented with the universal U/S uterine artery Doppler screening strategy over a RF based approach. Conclusion: A first trimester preeclampsia U/S screening strategy using uterine artery Doppler has minimal benefit over screening based on the ACOG recommended risk-factor based screening approach, identifying less than one preventable case of preeclampsia per year among a population of nearly 2,500 screened.