Expanded Fetal Growth Restriction Definition Identifies High Proportion of Umbilical Artery Doppler Anomalies

Area of Science:

• Perinatology and Maternal-Fetal Medicine
• Fetal Ultrasound and Doppler Studies
• Reproductive Endocrinology

Background:

• Fetal growth restriction (FGR) is a significant risk factor for adverse perinatal outcomes.
• The Society for Maternal-Fetal Medicine expanded FGR criteria to include abdominal circumference (AC) <10th percentile, independent of estimated fetal weight (EFW).
• Previous studies confirmed improved detection of small-for-gestational-age neonates with the expanded definition, but its impact on identifying abnormal umbilical artery Dopplers (UAD) was unknown.

Purpose of the Study:

• To compare the likelihood of detecting UAD abnormalities in fetuses meeting the expanded FGR definition (normal EFW with restricted AC) versus those identified by EFW alone.
• To evaluate the diagnostic performance of UAD abnormalities in identifying FGR using different definitional criteria.

Main Methods:

• Retrospective cohort study analyzing fetal growth ultrasounds meeting FGR criteria (EFW <10th percentile or AC <10th percentile with normal EFW).
• Comparison of UAD abnormality prevalence (elevated systolic/diastolic ratio, absent/reversed end-diastolic velocity) between fetuses identified by AC criteria alone versus EFW criteria.
• Receiver operator characteristic (ROC) curve analysis to assess the predictive value of UAD abnormalities for each FGR definition.

Main Results:

• Of 619 FGR scans, 441 (71%) met EFW criteria and 178 (29%) met AC criteria alone. FGR by AC alone was diagnosed earlier in gestation (30.4 vs. 35.4 weeks) and more frequently before 32 weeks (70% vs. 11%).
• The proportion of abnormal UAD was similar between groups (15% vs. 15%). However, using EFW alone would have missed 29% of abnormal UAD findings.
• A combined definition of FGR (considering both EFW and AC) demonstrated the highest detection rate for abnormal UAD (Area Under Curve: 0.78), outperforming EFW alone (0.69) and AC alone (0.73).

Conclusions:

• An FGR definition incorporating both EFW and AC significantly enhances the detection of abnormal UAD compared to using EFW criteria alone.
• Fetuses with restricted AC show a similar likelihood of abnormal UAD indices as those meeting FGR criteria by EFW.
• The expanded FGR definition facilitates earlier detection of FGR and improves the identification of associated abnormal Doppler findings.