The Association between discordant umbilical arterial resistance in growth-restricted fetuses and adverse outcomes.

BACKGROUND: Assessing the umbilical artery pulsatility index (UA PI) via Doppler measurements plays a critical role in evaluating fetal growth impairment. This study aims to investigate perinatal outcomes associated with discordant PIs of umbilical arteries (UAs) in growth-restricted fetuses.

METHODS: In this retrospective cohort study, all singleton pregnancies were included if their estimated fetal weight (EFW) and/or abdominal circumference (AC) fell below the 10th percentile for gestational age (2017-2022). Eligible cases included singleton pregnancies with concurrent sampling of both UAs within 14 days of birth at the US evaluation closest to delivery. Exclusion criteria comprised births before 22 weeks gestation, evidence of absent/reverse end-diastolic flow in either UA and known fetal genetic/structural anomalies. The study compared cases with discordant UA pulsatility index (PI) values (defined as one UA-PI ≤ 95th percentile and the other UA-PI > 95th percentile for gestational age) to pregnancies where both UAs had normal PI values and those with both UAs displaying abnormal PI values. The primary outcome assessed was the occurrence of composite adverse neonatal outcomes. Multivariable logistic regressions were performed, adjusting for relevant covariates.

RESULTS: The study encompassed 1,014 patients, including 194 (19.1%) with discordant UA PI values among those who had both UA sampled close to delivery, 671 (66.2%) with both UAs having normal PI values and 149 (14.7%) with both UAs exhibiting abnormal values. Pregnancies with discordant UAs PI displayed compromised sonographic parameters compared to those with both UAs showing normal PI values. Similarly, the number of the abnormal UAs PI was associated with adverse perinatal in a dose response manner. Cases with one abnormal (discordant) UA PI showed favorable sonographic parameters and perinatal outcomes compared to those with both abnormal UA PI values and cases with both UAs abnormal PI values showed worse sonographic parameters and perinatal outcomes compared to those with discordant UA PI. Multivariate analysis revealed that discordant UAs PI was significantly and independently associated with composite adverse perinatal outcomes, with an adjusted odds ratio (aOR) of 1.75 (95% confidence interval [CI] 1.24-2.47).

CONCLUSION: Evaluating the resistance indices of both umbilical arteries may provide useful data and assist in assessing adverse perinatal outcomes among growth-restricted fetuses.