Background: The uterine artery plays a critical role in fetal oxygenation and nutrient delivery during pregnancy. Abnormal uterine artery Doppler (UAD) indices, such as elevated pulsatility index (PI) and diastolic notching, are associated with adverse outcomes like fetal distress (FD), preeclampsia, and fetal growth restriction (FGR). Despite its clinical utility, the predictive accuracy of UAD in the second and third trimesters remains variable. Objective: This systematic review aimed to evaluate the diagnostic performance of UAD indices in predicting FD and related perinatal complications during the second and third trimesters of pregnancy. Methods: Following PRISMA 2020 guidelines, a comprehensive search of PubMed, Scopus, and Web of Science was conducted (January 2015–May 2025). Studies assessing UAD indices in singleton pregnancies ≥18 weeks were included. Two reviewers independently screened records, extracted data, and appraised study quality using the Newcastle-Ottawa Scale. Results: Of 204 records, 23 studies met inclusion criteria. In the second trimester, elevated PI (>95th percentile multiples of the median) showed moderate sensitivity and high specificity for FD. Bilateral notching improved specificity but not sensitivity. Third-trimester PI (>1.5 multiples of the median) had similar specificity but lower sensitivity for predicting emergency cesarean delivery due to FD. Bilateral notching in late gestation correlated strongly with adverse neonatal outcomes. Conclusion: UAD indices, particularly in the second trimester, offer high specificity for identifying pregnancies at risk of FD and adverse outcomes. However, sensitivity limitations highlight the need for multimodal screening. Standardized protocols and integrated risk models are essential for optimizing clinical utility |
