Background: Fetal growth restriction can result from a variety of maternal, fetal, and placental conditions. Umbilical artery Doppler assesses the impedance to blood flow along the fetal component of the placental unit. An abnormal umbilical artery waveform reflects the presence of placental insufficiency and can help differentiate a growth-restricted fetus from the constitutionally small, thus guiding further management. The presence of persistently absent end-diastolic flow and reversed end-diastolic flow is an indication for inpatient antenatal surveillance and preterm delivery. There is no consensus on the optimal management of intermittent absent end-diastolic flow owing to a lack of data to support the ideal delivery timing for growth-restricted fetuses with this finding.
Objective: This study aimed to estimate the risks of adverse perinatal outcomes among growth-restricted pregnancies with persistently elevated, intermittently absent, and persistently absent end-diastolic flow. Fetal growth restriction is a common condition that is associated with an increased risk of fetal morbidity and mortality. Intermittently absent umbilical artery end-diastolic flow may be identified among pregnancies with fetal growth restriction. The fetal risks associated with persistently absent end-diastolic flow have been described. However, the risks associated with intermittent absent end-diastolic flow are not as well-known.
Study design: We performed a retrospective cohort study including nonanomalous, singleton, growth-restricted pregnancies that received umbilical artery Doppler assessment at our institution from 2009 to 2020. Fetuses were classified into the following 3 categories: elevated umbilical artery Doppler, intermittent absent end-diastolic flow, and persistently absent end-diastolic flow. The Doppler categories were classified by the most severe in the pregnancy. The primary outcome was a composite of neonatal morbidity.
Results: Total 233 fetuses met the criteria. Of which 78 (33.0%) had elevated umbilical artery Doppler waveforms, 37 (16.0%) had intermittent absent end-diastolic flow, and 119 (51.0%) had absent end-diastolic flow. The composite outcome was statistically different between the groups, occurring in 16.9% with elevated umbilical artery Doppler waveforms (13/77), 35.1% (12/39) with intermittent absent end-diastolic flow, and 56.3% (65/127) with absent end-diastolic flow (P<.001). The odds ratio for the composite outcome was significantly increased in absent end-diastolic flow (odds ratio, 6.15; 95% confidence interval, 3.14-12.80) and was not significantly increased for intermittently absent end-diastolic flow (odds ratio, 2.46; 95% confidence interval, 0.98-6.19) when compared with elevated umbilical artery Doppler waveforms. When adjusted for gestational age at delivery and antenatal steroids, no difference was seen in the primary outcome for intermittent absent end-diastolic flow (adjusted odds ratio, 0.73; 95% confidence interval, 0.20-2.68) and absent end-diastolic flow (adjusted odds ratio, 1.44; 95% confidence interval, 0.51-4.07).
Conclusion: Among growth-restricted pregnancies, intermittent absent end-diastolic flow is associated with a similar rate of composite neonatal morbidity as persistently elevated Doppler waveforms. In addition, there is no difference in composite neonatal morbidity between the 3 groups when corrected for gestational age at delivery and antenatal steroid administration. These similar outcomes should be considered when creating an antenatal surveillance plan and discussing the potential for outpatient management.
Keywords: Doppler; absent end-diastolic flow; gestational age; neonatal morbidity; neonatal outcomes; pulsality index; ultrasound; umbilical artery.
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