Management of Concerning Placental Blood Flow at 38 Weeks Gestation
Deliver this patient between 37-38 weeks of gestation if concerning placental blood flow is associated with fetal growth restriction (FGR) and abnormal umbilical artery Doppler findings. 1
Immediate Assessment Required
First, clarify what "concerning placental blood flow" means in this specific case:
- Umbilical artery (UA) Doppler findings: Check for elevated resistance (pulsatility index >95th percentile), absent end-diastolic velocity (AEDV), or reversed end-diastolic velocity (REDV)
- Estimated fetal weight (EFW): Determine if <10th percentile (FGR diagnosis) or <3rd percentile (severe FGR)
- Amniotic fluid volume: Assess for oligohydramnios
- Middle cerebral artery Doppler: Evaluate for brain-sparing effect (cerebral-placental ratio)
Delivery Timing Algorithm
If FGR is Present (EFW <10th percentile):
At 38 weeks with normal UA Doppler:
- Deliver at 38-39 weeks when EFW is between 3rd-10th percentile with normal umbilical artery Doppler 1
With abnormal UA Doppler (elevated resistance but no AEDV/REDV):
- Deliver immediately at 37 weeks - this patient is already past the recommended delivery window 1
- This applies to decreased diastolic flow (flow ratios >95th percentile) without absent or reversed flow
With severe FGR (EFW <3rd percentile):
- Deliver immediately at 37 weeks regardless of Doppler findings 1
With AEDV:
- These cases should have been delivered at 33-34 weeks 1
- At 38 weeks, deliver immediately
With REDV:
- These cases should have been delivered at 30-32 weeks 1
- At 38 weeks, deliver immediately with heightened surveillance
Critical Management Points
Surveillance Before Delivery:
If delivery is not immediate (e.g., awaiting operating room availability):
- Perform cardiotocography (CTG) monitoring at least 1-2 times daily if AEDV/REDV present 1
- Weekly CTG if FGR without AEDV/REDV 1
- Consider hospitalization for REDV cases 1
Mode of Delivery:
Cesarean delivery should be strongly considered when:
- AEDV or REDV is present 1, 2
- The entire clinical scenario suggests fetal compromise
- Growth-restricted fetuses with abnormal Doppler have 75-95% rates of intrapartum fetal heart rate decelerations requiring cesarean delivery 1
Vaginal delivery may be attempted only if:
- FGR with normal umbilical artery Doppler
- Continuous fetal monitoring is available
- Immediate cesarean capability exists
Additional Interventions:
Not needed at 38 weeks:
- Antenatal corticosteroids (only indicated <36+6 weeks) 1, 2
- Magnesium sulfate for neuroprotection (only indicated <32 weeks) 1, 2
Consider:
- Cord arterial and venous pH collection at delivery 2
- Placental histopathologic examination to guide future pregnancy management 2
Common Pitfalls to Avoid
Waiting beyond 37 weeks with abnormal Doppler: The risk of stillbirth increases significantly, and these pregnancies should have been delivered earlier 1
Relying solely on biophysical profile: While useful for immediate fetal well-being, umbilical artery Doppler is the primary surveillance tool for FGR management 1
Attempting vaginal delivery with AEDV/REDV: These fetuses have extremely high rates of intrapartum compromise 1
Delaying delivery for "fetal maturity": At 38 weeks, the fetus is term; further delay with concerning placental blood flow only increases risk without benefit
If No FGR is Present
If placental blood flow concerns exist without FGR (normal fetal size):
- Increased uterine artery resistance alone in third trimester warrants increased surveillance 2
- Weekly ultrasound assessment of fetal growth, amniotic fluid, and UA Doppler 2
- Delivery timing depends on development of FGR or other complications
- Without FGR development, delivery can proceed at 39-40 weeks with close monitoring
The key distinction is whether FGR is present - this fundamentally changes management from surveillance to active delivery planning.