Cut-off for Diagnosing IUGR in Anomaly Scan

Diagnostic Criteria

Intrauterine growth restriction (IUGR) is defined as sonographic estimated fetal weight (EFW) below the 10th percentile for gestational age, according to the American College of Obstetricians and Gynecologists 1, 2, 3
IUGR is diagnosed when the EFW is below the 10th percentile for gestational age and/or abdominal circumference (AC) is below the 10th percentile, as recommended by the American College of Obstetricians and Gynecologists 4, 5, 6
Severe IUGR is defined as EFW below the 3rd percentile, as defined by the American College of Obstetricians and Gynecologists 4, 5, 6

Abnormal umbilical artery Doppler (pulsatility index, resistance index, or systolic-to-diastolic ratio greater than the 95th percentile for gestational age) is a parameter to confirm pathological growth restriction, according to the American College of Obstetricians and Gynecologists 4, 5
Absent or reversed end-diastolic velocity (AEDV or REDV) in the umbilical artery is a parameter to confirm pathological growth restriction, as recommended by the American College of Obstetricians and Gynecologists 4, 5
Reduced growth velocity (change in AC of <5 mm over 14 days or AC/EFW crossing centiles with >30% reduction) is a parameter to confirm pathological growth restriction, according to the American College of Obstetricians and Gynecologists 7

Early-onset IUGR is diagnosed at <32 weeks gestation, as defined by the American College of Obstetricians and Gynecologists 5, 6
Late-onset IUGR is diagnosed at ≥32 weeks gestation, according to the American College of Obstetricians and Gynecologists 5, 6

Once IUGR is diagnosed, serial umbilical artery Doppler assessment should be performed to assess for deterioration, as recommended by the American College of Obstetricians and Gynecologists 5, 6
Initial assessment should occur every 1-2 weeks, according to the American College of Obstetricians and Gynecologists 5, 6
If umbilical artery Doppler remains normal after initial assessment, a less frequent interval (every 2-4 weeks) may be considered, as recommended by the American College of Obstetricians and Gynecologists 5, 6
For EFW between 3rd-9th percentile with normal umbilical artery Doppler, follow-up should include umbilical artery Doppler every 1-2 weeks initially, then every 2-4 weeks if stable, according to the American College of Obstetricians and Gynecologists 5, 6
For severe IUGR (EFW <3rd percentile), weekly umbilical artery Doppler evaluation and weekly CTG should be performed, as recommended by the American College of Obstetricians and Gynecologists 5, 6

Umbilical artery Doppler evaluation helps differentiate the hypoxic growth-restricted fetus from the non-hypoxic small fetus, reducing unnecessary interventions, according to the American College of Obstetricians and Gynecologists 8, 9
For pregnancies with abnormal umbilical artery Doppler (AEDV/REDV), more intensive monitoring is required, including Doppler assessment 2-3 times per week for AEDV, as recommended by the American College of Obstetricians and Gynecologists 5, 6
Hospital admission should be considered if fetal surveillance more often than 3 times per week is deemed necessary, according to the American College of Obstetricians and Gynecologists 8, 9
Early-onset IUGR (<32 weeks) may warrant genetic testing, including chromosomal microarray analysis (CMA) when IUGR is accompanied by fetal malformations or polyhydramnios, as recommended by the American College of Obstetricians and Gynecologists 4, 6

The American College of Obstetricians and Gynecologists recommends using both serial ultrasound for growth monitoring and umbilical artery Doppler studies together to optimize outcomes in pregnancies with a prior history of intrauterine growth restriction (IUGR) 10, 11

The American College of Obstetricians and Gynecologists suggests that comprehensive surveillance requires both serial ultrasound for growth monitoring and umbilical artery Doppler studies to detect declining fetal growth patterns and diagnose IUGR 10, 11