How do I manage a pregnancy with an elevated umbilical artery pulsatility index and reduced diastolic flow?

Management of Elevated Umbilical Artery Pulsatility Index with Decreased Diastolic Flow

The management strategy depends critically on gestational age and the severity of diastolic flow abnormality: at term (≥37 weeks), delivery is indicated; preterm with decreased but present end-diastolic flow requires intensive surveillance with delivery timing based on progression; absent or reversed end-diastolic flow (AREDV) mandates hospitalization and expedited delivery after corticosteroids. 1

Initial Assessment and Risk Stratification

When elevated umbilical artery pulsatility index with decreased diastolic flow is detected, immediately classify the severity:

• Elevated PI with present end-diastolic flow: Represents early placental insufficiency with increased vascular resistance but maintained perfusion 1
• Absent end-diastolic flow (AEDV): Indicates severe placental compromise with obliteration of approximately 70% of placental tertiary villi arteries 1, 2
• Reversed end-diastolic flow (REDV): Represents advanced placental failure with >20% perinatal mortality risk 1

The distinction between these categories is critical as absent or reversed flow carries dramatically higher risks for intraventricular hemorrhage, bronchopulmonary dysplasia, and perinatal mortality compared to elevated but present flow 3.

Gestational Age-Specific Management

Term Pregnancy (≥37 weeks)

Proceed to delivery. 1 Abnormal umbilical artery Doppler findings at term are an indication for delivery regardless of other testing, as the risks of continued pregnancy outweigh any benefits of expectant management 1.

Preterm Pregnancy with Elevated PI but Present End-Diastolic Flow

Initiate intensive surveillance rather than immediate delivery to avoid iatrogenic prematurity 1:

• Biophysical profile (BPP) or modified BPP: Weekly to twice-weekly monitoring 1
• Repeat umbilical artery Doppler: Every 1-2 weeks initially to monitor for progression to AEDV 4, 2
• Cardiotocography (NST): Weekly as part of modified BPP, more frequently if oligohydramnios present 1
• Growth assessment: Every 2-3 weeks to monitor for worsening growth restriction 4
• Middle cerebral artery Doppler: Consider adding to detect brain-sparing physiology, which may precede umbilical artery deterioration 1, 4

Recent evidence suggests that intermittent AEDV carries similar neonatal outcomes to persistently elevated Doppler when corrected for gestational age at delivery, supporting continued surveillance rather than immediate delivery for this intermediate category 5.

Preterm Pregnancy with Absent or Reversed End-Diastolic Flow

Hospitalize immediately and prepare for expedited delivery 6:

• Corticosteroids: Administer immediately if <33 6/7 weeks or between 34 0/7-36 6/7 weeks without prior course 6
• Magnesium sulfate: Give for neuroprotection if <32 weeks 6
• Intensive monitoring: Cardiotocography at least 1-2 times daily, potentially more frequently 6
• Ductus venosus Doppler: Daily assessment, as absent or reversed A-wave predicts stillbirth with 100% sensitivity and 80% specificity when present >7 days 1
• Neonatal team notification: Alert immediately for delivery planning 6

Delivery timing for AEDV/REDV:

• ≥30 weeks: Deliver within 24-48 hours after corticosteroid administration, ideally after 24 hours but not beyond 48 hours 6
• <30 weeks: Balance extreme prematurity risks against imminent fetal demise risk; delivery typically indicated within 24-48 hours 6

The TRUFFLE trial demonstrated that timing delivery based on ductus venosus waveform changes may improve developmental outcomes at 2 years, particularly when delivery occurs before 32 weeks with sequential assessment of both ductus venosus and cardiotocography 1.

Comprehensive Doppler Surveillance Strategy

Beyond umbilical artery assessment, incorporate additional Doppler parameters:

• Middle cerebral artery (MCA): Decreased MCA pulsatility index indicates cerebral vasodilation (brain-sparing), which may occur before umbilical artery changes and is associated with neurobehavioral impairment 1, 4
• Cerebroplacental ratio (CPR): Abnormal CPR may be an earlier predictor of adverse outcome than umbilical artery abnormalities alone, though insufficient evidence exists for stand-alone clinical decision-making 4
• Ductus venosus: Absent or reversed A-wave indicates severe cardiac compromise and imminent decompensation 1, 6
• Umbilical vein pulsatility: If present, indicates severe cardiac dysfunction with elevated right atrial pressures and requires delivery within 24-48 hours 6

Umbilical artery Doppler use in high-risk pregnancies with suspected IUGR significantly decreases perinatal deaths (1.2% vs 1.7%; RR 0.71,95% CI 0.52-0.98) and reduces unnecessary labor inductions and cesarean deliveries 1.

Critical Pitfalls to Avoid

• Do not confuse umbilical vein pulsatility with umbilical artery pulsatility: Umbilical vein pulsatility is a much more ominous late-stage finding indicating imminent decompensation 6
• Do not delay delivery for routine surveillance intervals with AEDV/REDV: The fetus is at imminent risk of demise and requires expedited delivery 6
• Do not rely solely on BPP results: Doppler findings, particularly absent/reversed flow and venous Doppler abnormalities, supersede BPP results in determining delivery urgency 1, 6
• Do not assume normal umbilical artery Doppler excludes placental insufficiency in late-onset growth restriction: 15-20% of late-onset growth-restricted fetuses with normal umbilical artery Doppler show cerebral vasodilation on MCA assessment 2
• Do not use middle cerebral artery or ductus venosus Doppler as stand-alone tests: Current evidence supports umbilical artery Doppler as the primary surveillance tool, with other vessels providing supplementary prognostic information 1

Technical Considerations

For optimal reproducibility, obtain umbilical artery Doppler waveforms at the abdominal cord insertion, in the absence of fetal breathing movements, when the waveform is uniform 1, 2. Either systolic-to-diastolic (S/D) ratio or pulsatility index (PI) is sufficient for clinical management; when end-diastolic flow is absent, PI should be used as S/D ratio becomes immeasurable 1.