What are the American College of Obstetricians and Gynecologists (ACOG) guidelines for managing Intrauterine Growth Restriction (IUGR)?

ACOG Guidelines for Managing Intrauterine Growth Restriction (IUGR)

Umbilical artery Doppler assessment should be the primary surveillance tool for IUGR management, with timing of delivery based on Doppler findings and severity of growth restriction. 1

Diagnosis and Initial Evaluation

• IUGR is defined as estimated fetal weight (EFW) below the 10th percentile for gestational age
• Severe IUGR is defined as EFW below the 3rd percentile

When IUGR is suspected:

• Perform detailed obstetrical ultrasound examination (CPT code 76811), especially for early-onset IUGR (<32 weeks) as up to 20% of cases are associated with fetal or chromosomal abnormalities 1
• Offer prenatal diagnostic testing with chromosomal microarray analysis (CMA) when:
  • IUGR is detected with fetal malformation and/or polyhydramnios 1
  • Unexplained isolated IUGR is diagnosed at <32 weeks gestation 1
• PCR testing for cytomegalovirus (CMV) is recommended for women with unexplained IUGR who undergo amniocentesis 1
• Screening for toxoplasmosis, rubella, or herpes is NOT recommended unless other risk factors are present 1

Surveillance Protocol

Umbilical Artery Doppler Assessment

• Once IUGR is diagnosed, serial umbilical artery Doppler assessment should be performed to monitor for deterioration 1
• Surveillance frequency based on severity:
  • Normal umbilical artery Doppler: Weekly assessment 1
  • Decreased end-diastolic velocity or severe IUGR (EFW <3rd percentile): Weekly umbilical artery Doppler 1
  • Absent end-diastolic velocity (AEDV): Doppler assessment 2-3 times per week 1
  • Reversed end-diastolic velocity (REDV): Hospitalization with daily cardiotocography (CTG) monitoring 1-2 times per day 1

Additional Monitoring

• Weekly cardiotocography (CTG) testing after viability for IUGR without AEDV/REDV 1
• Increase CTG frequency when IUGR is complicated by AEDV/REDV or other comorbidities 1
• Traditional surveillance includes:
  • Twice weekly nonstress testing with weekly amniotic fluid evaluation, OR
  • Weekly biophysical profile testing 1

Not Recommended for Routine Management

• Doppler assessment of the ductus venosus, middle cerebral artery, or uterine artery 1

Timing of Delivery

Delivery timing should be based on umbilical artery Doppler findings and severity of growth restriction:

1. Normal umbilical artery Doppler with EFW between 3rd-10th percentile:

   • Deliver at 38-39 weeks gestation 1

2. Decreased diastolic flow (without AEDV/REDV) OR severe IUGR (EFW <3rd percentile):

   • Deliver at 37 weeks gestation 1

3. Absent end-diastolic velocity (AEDV):

   • Deliver at 33-34 weeks gestation 1

4. Reversed end-diastolic velocity (REDV):

   • Deliver at 30-32 weeks gestation 1

Additional Interventions

• Antenatal corticosteroids: Recommended if delivery is anticipated before 33 6/7 weeks or between 34 0/7 and 36 6/7 weeks in women at risk of preterm delivery within 7 days 1
• Magnesium sulfate: Recommended for fetal and neonatal neuroprotection for pregnancies <32 weeks gestation 1
• Mode of delivery: Consider cesarean delivery for pregnancies with AEDV/REDV based on the entire clinical scenario 1

Interventions NOT Recommended

• Low-molecular-weight heparin for prevention of recurrent IUGR 1
• Sildenafil or activity restriction for in utero treatment of IUGR 1

Common Pitfalls and Caveats

1. Doppler interpretation: Ensure proper technique and interpretation of umbilical artery Doppler waveforms, as management decisions heavily rely on these findings.

2. Distinguishing IUGR from constitutionally small fetuses: Not all small fetuses are pathologically growth restricted. Normal Doppler studies may help identify constitutionally small but healthy fetuses.

3. Early-onset vs. late-onset IUGR: Early-onset IUGR (<32 weeks) is more likely associated with placental insufficiency and abnormal Doppler findings, requiring more intensive surveillance.

4. Corticosteroid administration: While generally beneficial, close observation for 48-72 hours after administration is reasonable due to potential transient increased physiologic and metabolic demands 1.