Management of Fetal Growth Restriction with Marginal Cord Insertion at 36.2 Weeks
For a patient at 36.2 weeks with marginal cord insertion and significant drop in estimated fetal weight from 60th to 22nd percentile, delivery should be planned within the next week due to the risk of progressive placental insufficiency and potential adverse perinatal outcomes.
Assessment of Current Status
Evaluation of Growth Restriction
- The patient has demonstrated a significant drop in estimated fetal weight (EFW) from 60th to 22nd percentile over one month
- While the current EFW is still above the 10th percentile, this rapid decline in growth trajectory is concerning
- Marginal cord insertion (defined as cord insertion-to-placental edge distance ≤1.0 cm) is associated with increased risk of adverse outcomes 1
- The combination of marginal cord insertion and declining growth velocity suggests placental insufficiency
Immediate Assessment Needed
- Umbilical artery Doppler studies to assess placental function and determine management
- Assessment of amniotic fluid volume
- Fetal monitoring with cardiotocography (CTG)
Management Algorithm
Step 1: Doppler Assessment
Perform umbilical artery Doppler studies immediately to determine severity:
- Normal end-diastolic flow: Plan delivery at 37 weeks (within next few days)
- Decreased end-diastolic flow: Plan delivery immediately (at 36.2 weeks)
- Absent end-diastolic flow: Hospitalize, administer corticosteroids, and deliver within 24-48 hours
- Reversed end-diastolic flow: Immediate hospitalization and delivery after corticosteroid administration
Step 2: Fetal Surveillance Until Delivery
- Daily cardiotocography (CTG) testing
- Twice weekly biophysical profile (BPP)
- Repeat Doppler studies every 2-3 days if initial assessment shows normal flow
Step 3: Delivery Planning
Based on the Society for Maternal-Fetal Medicine guidelines 2:
- With normal Doppler but significant growth decline: Deliver at 37 weeks (within next few days)
- With decreased end-diastolic flow: Deliver immediately at current gestation (36.2 weeks)
- With severe FGR (EFW <3rd percentile): Deliver immediately regardless of Doppler findings
Rationale for Management
The rapid decline in fetal growth percentile (from 60th to 22nd) over one month is concerning for developing fetal growth restriction, even though the current EFW is still above the traditional 10th percentile cutoff. This significant change in growth trajectory combined with marginal cord insertion warrants prompt intervention 2.
The Society for Maternal-Fetal Medicine recommends delivery at 37 weeks for pregnancies with fetal growth restriction and abnormal umbilical artery Doppler waveforms or severe FGR with EFW <3rd percentile 2. Given that the patient is already at 36.2 weeks, the risks of continued intrauterine stay likely outweigh the benefits of reaching 37 completed weeks.
Important Considerations
- Antenatal corticosteroids should be considered if delivery is planned before 36 6/7 weeks 2
- Mode of delivery should be determined based on fetal status, with cesarean delivery considered if there are abnormal Doppler findings 2
- The presence of marginal cord insertion increases the risk of adverse outcomes including fetal growth restriction, oligohydramnios, and intrauterine fetal demise 1
- Serial growth assessments are more predictive of adverse outcomes than a single measurement 3
Pitfalls to Avoid
- Do not delay delivery if Doppler studies show absent or reversed end-diastolic flow
- Do not rely solely on the EFW percentile without considering the significant drop in growth trajectory
- Avoid underestimating the significance of marginal cord insertion, which is associated with increased risk of adverse outcomes when the cord insertion-to-placental edge distance is ≤1.0 cm 1
- Remember that ultrasound estimation of fetal weight may underestimate actual weight in cases of suspected FGR 4