Role of routine uterine artery Doppler at 18-22 and 24-28 weeks' gestation following routine first-trimester screening for pre-eclampsia.

Objectives: To assess the performance of mean uterine artery pulsatility index (UtA-PI) at 18-22 and 24-28 weeks of gestation in the prediction of pre-eclampsia (PE) and small-for-gestational age (SGA), and its role in reassessing the risk of PE and SGA in pregnancies screened for PE in the first trimester.

Methods: This was a retrospective observational cohort study of 4464 women with singleton pregnancy screened routinely for PE in the first trimester, using the Gaussian algorithm, from March 2019 to May 2021, and who underwent UtA-PI assessment at 18-22 gestational weeks. Women were categorized as low risk or high risk based on the risk index obtained after first-trimester screening for PE. In high-risk patients, UtA-PI was also assessed at 24-28 weeks of gestation. Sensitivity, specificity, positive predictive value, negative predictive value (NPV), positive likelihood ratio, negative likelihood ratio and area under the receiver-operating-characteristics curve were calculated to assess the performance of UtA-PI at 18-22 and 24-28 weeks in predicting PE and SGA in the high-risk group. In all participants, different UtA-PI percentiles at 18-22 or 24-28 weeks, or their combination, were analyzed to explore their role in reassessing the risk of PE and SGA following first-trimester PE screening.

Results: The performance of UtA-PI at 18-22 and 24-28 weeks in the high-risk group was good for predicting preterm PE and preterm SGA, and excellent for predicting early-onset PE and early-onset SGA, with an NPV of > 97% for all outcomes. In the low-risk group, UtA-PI ≥ 95^th percentile at 18-22 weeks' gestation identified a subgroup of pregnancies with a significantly higher risk of preterm SGA compared to the low-risk group. In the high-risk group, UtA-PI < 60^th percentile at 18-22 weeks' gestation, UtA-PI < 85^th percentile at 24-28 weeks' gestation, and UtA-PI < 85^th percentile at 24-28 weeks' gestation in women with UtA-PI ≥ 60^th percentile at 18-22 weeks, identified subgroups of pregnancies with a risk of PE and SGA comparable to that of the low-risk group.

Conclusions: The performance of UtA-PI at 18-22 and 24-28 gestational weeks in high-risk pregnancies identified during first-trimester screening for PE is similar to that in the general population. The risk of PE and SGA in a high-risk cohort can be reassessed by measuring UtA-PI at 18-22 weeks, 24-28 weeks or both, allowing adjustment of follow-up, particularly de-escalation of care. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.