Elevated umbilical artery systolic/diastolic ratio in the absence of fetal growth restriction

Purpose: To evaluate whether patients with isolated elevation of umbilical artery (UA) systolic/diastolic (S/D) ratio are at increased risk for adverse perinatal outcome. Methods: This is a retrospective cohort study of 330 patients who underwent routine evaluation at our maternal fetal medicine center. We regularly perform UA S/D ratio analysis with every third trimester sonogram. All identified patients were included and divided into four groups based on estimated fetal weight (EFW) and UA S/D ratio. Perinatal outcome was compared between the groups. Results: Regardless of the EFW, fetuses with persistent elevated UA S/D ratio showed significantly more preterm deliveries (p <.001), neonatal intensive care unit (NICU) admissions (p <.001), longer stay in the NICU (p <.001) and lower birth weight (p <.001) relative to controls. Stepwise logistic regression analysis demonstrated that being a member in any study group significantly and independently predicted birth weight less than the 10th percentile and preterm delivery. Patients with persistently elevated S/D ratio were significantly and independently from other factors, more likely to have a newborn admitted to the NICU. Conclusion: Our results indicate a suboptimal perinatal outcome in all pregnancies with an elevated UA S/D ratio. These fetuses may benefit from intensive monitoring.