What is the management of severe intrauterine growth restriction (IUGR)?

Management of Severe Intrauterine Growth Restriction (IUGR)

For severe IUGR (estimated fetal weight <3rd percentile), deliver at 37 weeks of gestation if umbilical artery Doppler shows decreased diastolic flow, at 33-34 weeks for absent end-diastolic velocity, and at 30-32 weeks for reversed end-diastolic velocity. 1

Initial Diagnostic Workup

When severe IUGR is identified, perform a comprehensive anatomical survey to identify structural anomalies, as up to 20% of early-onset cases have chromosomal or fetal abnormalities 1:

• Offer chromosomal microarray analysis for unexplained isolated IUGR diagnosed before 32 weeks of gestation 1, 2
• Offer chromosomal microarray analysis at any gestational age if IUGR is accompanied by fetal malformation or polyhydramnios 1
• Perform PCR testing for cytomegalovirus in women with unexplained IUGR who undergo amniocentesis 1, 2
• Do not routinely screen for toxoplasmosis, rubella, or herpes unless specific risk factors are present 1, 2

Surveillance Protocol Based on Doppler Findings

Umbilical Artery Doppler Assessment

The cornerstone of IUGR surveillance is serial umbilical artery Doppler, which significantly reduces perinatal mortality 1, 3:

• Weekly umbilical artery Doppler for severe IUGR (EFW <3rd percentile) or decreased end-diastolic velocity 1, 2
• Doppler assessment 2-3 times per week when absent end-diastolic velocity is detected 1, 2
• Do not use middle cerebral artery, ductus venosus, or uterine artery Doppler for routine clinical management 1

Cardiotocography (Fetal Heart Rate Monitoring)

• Weekly cardiotocography after viability for IUGR without absent/reversed end-diastolic velocity 1, 2
• Increase frequency to at least 1-2 times daily when absent or reversed end-diastolic velocity is present 1, 2

Management of Reversed End-Diastolic Velocity

When reversed end-diastolic velocity is detected, this represents the most severe form of placental insufficiency requiring immediate action 1:

• Hospitalize the patient immediately 1
• Administer antenatal corticosteroids 1
• Perform cardiotocography at least 1-2 times daily 1
• Consider delivery based on gestational age and overall clinical picture 1
• Monitor closely for 48-72 hours after corticosteroid administration, as transient return of end-diastolic flow may occur in two-thirds of cases 1, 3

Timing of Delivery: A Gestational Age-Based Algorithm

The delivery timing depends critically on umbilical artery Doppler findings and gestational age 1:

Normal Umbilical Artery Doppler

• EFW 3rd-10th percentile: Deliver at 38-39 weeks 1, 3

Decreased Diastolic Flow (but not absent/reversed)

• Deliver at 37 weeks of gestation 1, 3

Severe IUGR (EFW <3rd percentile) with Normal or Decreased Flow

• Deliver at 37 weeks of gestation 1, 3

Absent End-Diastolic Velocity

• Deliver at 33-34 weeks of gestation if fetal surveillance remains reassuring 1, 3

Reversed End-Diastolic Velocity

• Deliver at 30-32 weeks of gestation if fetal surveillance remains reassuring 1, 3

Critical caveat: Each additional day in utero increases intact survival by 1-2% up until 32 weeks of gestation, making the balance between prematurity risks and ongoing placental insufficiency crucial 3

Antenatal Interventions

Corticosteroids

• Administer antenatal corticosteroids if delivery is anticipated before 33 6/7 weeks 1, 2
• Also administer between 34 0/7 and 36 6/7 weeks in women at risk of preterm delivery within 7 days who have not received a prior course 1, 2
• Administer corticosteroids when absent or reversed end-diastolic flow is noted at <34 weeks 1, 3

Magnesium Sulfate for Neuroprotection

• Administer intrapartum magnesium sulfate for fetal neuroprotection when delivery is anticipated at <32 weeks of gestation 1, 2, 3

Ineffective Interventions to Avoid

• Do not use low-molecular-weight heparin solely for prevention of recurrent IUGR 1
• Do not use sildenafil or activity restriction for in utero treatment of IUGR 1

Mode of Delivery

• Consider cesarean delivery for IUGR complicated by absent or reversed end-diastolic velocity based on the complete clinical scenario 1, 2, 3
• If umbilical artery end-diastolic flow is present, induction of labor with continuous fetal heart rate monitoring is recommended 1
• IUGR alone is not an absolute indication for cesarean delivery 1, 4

Common Pitfalls and How to Avoid Them

Pitfall #1: Confusing small for gestational age (SGA) with IUGR. SGA is simply a measurement below the 10th percentile, while IUGR implies pathologic growth restriction with evidence of placental insufficiency 4, 5.

Pitfall #2: Delaying delivery in the setting of reversed end-diastolic velocity beyond 32 weeks. The risk of stillbirth increases substantially, and the guidelines are clear about delivery timing 1, 3.

Pitfall #3: Using biophysical profile as the sole surveillance method. Umbilical artery Doppler is the primary surveillance tool and should not be replaced by biophysical profile alone 1.

Pitfall #4: Failing to administer corticosteroids in preterm IUGR due to concerns about fetal stress. Despite historical concerns, evidence supports corticosteroid use with close observation for 48-72 hours 1, 3.

Pitfall #5: Performing fetal growth assessments too frequently. Growth should be reassessed at intervals of no less than 2 weeks, ideally 3-4 weeks, due to inherent measurement error 2, 4.

Special Monitoring Considerations

• Monitor closely for development of maternal hypertensive disorders, as maternal hypertension is present in up to 70% of early-onset IUGR cases at delivery 3
• In the context of severe preterm preeclampsia with IUGR, expectant management beyond 48 hours (time needed for corticosteroids) may not provide additional benefit, as 85.7% of these fetuses are delivered within one week 6