What is the appropriate management for a 33-week gestational age female with fetal growth restriction (FGR) and estimated fetal weight at the 4th percentile?

Management of Fetal Growth Restriction at 33 Weeks with EFW at 4th Percentile

Immediately obtain umbilical artery Doppler studies to guide surveillance intensity and delivery timing, as this single test determines whether delivery should occur now versus weeks from now. 1

Initial Diagnostic Workup

Immediate Doppler Assessment

• Umbilical artery Doppler is the critical first test that stratifies risk and determines all subsequent management decisions 1, 2
• This single measurement will determine if delivery should occur at 30-32 weeks (reversed flow), 33-34 weeks (absent flow), 37 weeks (decreased flow), or 38-39 weeks (normal flow) 1, 2

Detailed Anatomic Survey

• Perform a detailed obstetrical ultrasound examination (CPT 76811) immediately, as early-onset FGR (<32 weeks) requires comprehensive structural evaluation 1
• Look specifically for structural malformations or polyhydramnios, as their presence mandates offering chromosomal microarray analysis regardless of gestational age 1

Genetic Testing Considerations

• Offer chromosomal microarray analysis via amniocentesis for unexplained isolated FGR diagnosed at <32 weeks of gestation 1
• If amniocentesis is performed, send PCR for cytomegalovirus testing 1
• Do not screen for toxoplasmosis, rubella, or herpes unless other specific risk factors are present 1

Surveillance Protocol Based on Doppler Results

If Normal Umbilical Artery Doppler

• Serial umbilical artery Doppler every 2 weeks 2
• Weekly cardiotocography (NST) after viability 1
• Plan delivery at 38-39 weeks if EFW remains between 3rd-10th percentile 1, 2

If Decreased End-Diastolic Velocity (elevated ratios >95th percentile)

• Weekly umbilical artery Doppler evaluation 1, 2
• Weekly cardiotocography testing 1
• Plan delivery at 37 weeks gestation 1, 2

If Absent End-Diastolic Velocity (AEDV)

• Doppler assessment 2-3 times per week 1, 2
• Increased frequency cardiotocography 1
• Plan delivery at 33-34 weeks gestation, as neonatal morbidity/mortality with AEDV exceeds complications of prematurity at this threshold 1, 2
• Strongly consider cesarean delivery given 75-95% risk of intrapartum fetal heart rate decelerations requiring emergency cesarean 2, 3

If Reversed End-Diastolic Velocity (REDV)

• Immediate hospitalization 1, 2
• Cardiotocography monitoring 1-2 times daily 1, 2
• Plan delivery at 30-32 weeks gestation due to severe placental dysfunction with high risk of fetal demise 1, 2
• Cesarean delivery is indicated given extreme fetal compromise 2, 3

Pre-Delivery Interventions

Antenatal Corticosteroids

• Administer betamethasone or dexamethasone immediately if delivery is anticipated before 33 6/7 weeks 2, 4
• Also indicated if delivery anticipated between 34 0/7 and 36 6/7 weeks in women at risk of delivery within 7 days 2

Magnesium Sulfate for Neuroprotection

• Administer if delivery anticipated at <32 weeks gestation for fetal and neonatal neuroprotection 2

Neonatology Coordination

• Coordinate care between maternal-fetal medicine and neonatology services, particularly if delivery may occur before 26 weeks or at <500g 2

Common Pitfalls to Avoid

• Do not use ductus venosus, middle cerebral artery, or uterine artery Doppler for routine clinical management decisions in early-onset FGR 1, 2, 5
• Do not rely solely on biophysical profile for surveillance 2
• Do not use low-molecular-weight heparin for prevention of recurrent FGR 1
• Do not use sildenafil or activity restriction for in utero treatment of FGR 1
• Do not delay delivery if umbilical artery Doppler shows AEDV or REDV, as the patient is already at or beyond recommended delivery thresholds 2, 3

Mode of Delivery Decision Algorithm

Cesarean Delivery Strongly Indicated If:

• Absent or reversed end-diastolic velocity on umbilical artery Doppler 1, 2, 3
• Non-reassuring fetal heart rate pattern on cardiotocography 2, 4
• Clinical scenario suggests severe fetal compromise 1, 2

Vaginal Delivery Reasonable If:

• Normal or only decreased (not absent) end-diastolic velocity 1
• Reassuring fetal heart rate monitoring 4
• Continuous fetal monitoring during labor is mandatory as FGR fetuses cannot tolerate labor stress well 4, 5

Post-Delivery Management

• Obtain cord arterial and venous pH at delivery to assess degree of fetal compromise 3
• Send placenta for histopathologic examination to guide future pregnancy management 3