What is the recommended evaluation and management for a pregnant patient with suspected intrauterine growth restriction?

Evaluation and Management of Intrauterine Growth Restriction (IUGR)

For suspected IUGR, immediately obtain umbilical artery Doppler assessment once the diagnosis is confirmed by ultrasound (estimated fetal weight <10th percentile), as this is the only surveillance modality with Level I evidence showing a 29% reduction in perinatal mortality and should guide all subsequent management decisions. 1

Initial Diagnostic Evaluation

Confirming the Diagnosis

• Define IUGR as an ultrasonographic estimated fetal weight or abdominal circumference below the 10th percentile for gestational age using population-based references such as Hadlock 1
• Perform detailed fetal anatomical ultrasound (CPT 76811) when IUGR is diagnosed before 32 weeks of gestation, as early-onset cases carry significantly higher morbidity and mortality risk 1, 2
• Obtain umbilical artery Doppler immediately upon diagnosis to stratify risk and determine surveillance intensity 1, 2

Genetic and Infectious Workup

• Offer chromosomal microarray analysis when IUGR occurs with fetal malformations, polyhydramnios, or both, regardless of gestational age 1, 2
• Offer chromosomal microarray analysis for unexplained isolated IUGR diagnosed before 32 weeks of gestation, as early-onset isolated IUGR has higher rates of chromosomal abnormalities 1, 2
• Perform PCR testing for cytomegalovirus only in women with unexplained IUGR who elect diagnostic amniocentesis 1, 2
• Do not routinely screen for toxoplasmosis, rubella, or herpes in IUGR pregnancies without other risk factors 1, 2

Surveillance Protocol Based on Doppler Findings

Umbilical Artery Doppler Surveillance

The 2020 SMFM guidelines provide the most current evidence-based surveillance algorithm:

• Normal or decreased end-diastolic velocity: Perform weekly umbilical artery Doppler evaluation 1
• Absent end-diastolic velocity: Increase Doppler assessment to 2-3 times per week 1
• Reversed end-diastolic velocity: Hospitalize immediately, administer antenatal corticosteroids, and perform cardiotocography at least 1-2 times daily 1

Cardiotocography (NST/BPP) Surveillance

• Begin weekly cardiotocography testing after viability for IUGR without absent or reversed end-diastolic velocity 1
• Increase frequency to twice weekly or more when IUGR is complicated by absent or reversed end-diastolic velocity or other comorbidities 1

Important Limitation

Do not use middle cerebral artery, ductus venosus, or uterine artery Doppler for routine clinical management decisions, as these lack randomized trial evidence showing benefit 1

Delivery Timing Algorithm

The timing of delivery must balance prematurity risks against ongoing placental insufficiency, guided primarily by umbilical artery Doppler findings:

Based on Doppler Results (Most Recent SMFM 2020 Guidelines)

• Reversed end-diastolic velocity: Deliver at 30-32 weeks of gestation 1
• Absent end-diastolic velocity: Deliver at 33-34 weeks of gestation 1
• Decreased diastolic flow (but present) OR severe IUGR (EFW <3rd percentile): Deliver at 37 weeks of gestation 1
• Normal Doppler with EFW 3rd-10th percentile: Deliver at 38-39 weeks of gestation 3

Antenatal Corticosteroids and Neuroprotection

• Administer antenatal corticosteroids if delivery is anticipated before 33 6/7 weeks of gestation 1, 2
• Administer intrapartum magnesium sulfate for fetal neuroprotection when delivery is anticipated before 32 weeks of gestation 1, 2

Mode of Delivery Considerations

• Consider cesarean delivery for IUGR complicated by absent or reversed end-diastolic velocity based on the complete clinical scenario, as these fetuses have limited physiologic reserve and may not tolerate labor 1, 2
• Studies report 75-95% of IUGR pregnancies with absent/reversed end-diastolic flow require cesarean delivery for intrapartum heart rate abnormalities 3

Interventions to Avoid

Do not use the following interventions, as they lack evidence of benefit or may cause harm:

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

Critical Pitfalls to Avoid

• Never delay delivery beyond recommended gestational ages based on Doppler findings, as this increases stillbirth risk 2
• Never rely on biophysical profile or nonstress testing alone without Doppler assessment in diagnosed IUGR, as Doppler provides superior prognostic information about placental function 2
• Never use normal fetal heart rate testing as the sole surveillance method, as early or compensated IUGR typically maintains normal heart rate patterns while significant vascular changes are already present on Doppler 3
• Never use Doppler as a screening tool in low-risk pregnancies, as it provides no benefit and may cause iatrogenic prematurity from false-positive results 4

Special Considerations

• Perform fetal growth evaluation at intervals of no less than 2 weeks, with evaluations every 3-4 weeks being more reliable due to inherent error in fetal biometry 3
• No antenatal test can predict stillbirth related to acute events such as placental abruption or cord accidents, regardless of test frequency 3, 4