246: Are intermittently elevated UA Doppler Pulsatility Indices associated with increased risk of neonatal morbidity in pregnancies with intrauterine growth restriction?

Abstract

Intrauterine growth restriction (IUGR) with persistently elevated umbilical artery Doppler Pulsatility Index (UA PI) (>95%) is associated with an increased risk of perinatal morbidity compared to IUGR with normal UA PI (≤95%). Clinically, intermittently elevated UA PI is observed, but the clinical significance is unknown. We aimed to estimate the risk of neonatal morbidity with intermittently elevated UA PI. This retrospective cohort study included all non-anomalous singleton, IUGR pregnancies receiving UA PI testing at a tertiary care prenatal diagnostic center from 01/2010-09/2016. Intrauterine growth restriction was defined as an estimated fetal weight ≤ 10% for gestational age. Women with consistently elevated UA PI or absent or reversed flow were excluded. Intermittently elevated UA PI was defined as having ≥1 UA PI >95% and ≥1 UA PI ≤95%. Women with intermittently elevated UA PI were matched 1:3 by gestational age at IUGR diagnosis to those with consistently normal UA PI. The primary outcome was a composite neonatal morbidity including ventilation, phototherapy, intraventricular hemorrhage, and necrotizing enterocolitis. Secondary outcomes included individual components of the composite, 5-minute APGAR score, umbilical cord artery pH, type of delivery, and interval from diagnosis of IUGR to delivery. 1893 women were included; of these, 143 (7.6%) had intermittently elevated UA PI and were matched to 452 controls. The risk of composite neonatal morbidity was not significantly different among IUGR pregnancies with intermittently elevated versus normal UA PI. Similarly, the individual components of the composite neonatal morbidity were not significantly different between the two groups. Intermittently elevated UA PI was not associated with differences in 5-minute APGAR scores, umbilical artery pH, rates of cesarean delivery (CD) or CD for fetal distress, or interval from diagnosis of IUGR to delivery. Intermittently elevated UA PI is not uncommon among IUGR pregnancies but is not associated with an increased risk of neonatal morbidity or CD. These data suggest intermittently elevated UA PI should be managed clinically as normal UA PI.