BACKGROUND AND PURPOSE:

• 2 common components used to identify SGA include
  • EFW
  • Growth curve to determine percentile
• Hadlock (US derived growth curve) remains an ultrasound standard, however there are 2 new curves using alternate formulae that may be more generalizable
  • Intergrowth-21st (INTG) method (international population)
  • Salomon method (Paris, France population)
• Blue et al. (Journal of Ultrasound in Medicine, 2018) compared the traditional Hadlock method with these 2 newer methods for the SGA

METHODS:

• Retrospective review
  • Singleton, non-anomalous, well-dates fetuses were examined within 2 weeks of delivery
• Fetal growth restriction (FGR): EFW <10th percentile
• SGA: Birth weight <10th percentile
• Estimated fetal weights and percentiles were calculated by
  • Hadlock method
  • INTG method
  • Salomon method
• Outcomes: Test characteristics to predict SGA were calculated using
  • EFW < 10th percentile (standard method)
  • Receiver operating characteristic (ROC) – derived FGR cutoffs

RESULTS:

• 831 pregnancies
  • SGA: 16.7%
• Plotting the ROC curves using a 10^th percentile cutoff, Hadlock performed better than the other methods in the prediction of SGA
• Comparing overall performance and accuracy of birth weight percentile prediction
  • Hadlock and INTG methods performed comparably (P = .08)
  • Hadlock area under the curve: 0.91
  • INTG area under the curve: 0.90
• Optimal EFW cutoffs
  • Hadlock: 15th percentile
  • INTG: 22nd percentile
• Salomon method performed less well than other 2 methods (P<.001)
  • Area under the curve: 0.82

CONCLUSION:

• The traditional Hadlock had the best sensitivity and ROCs to predict SGA (using 10% cutoff)
• Hadlock was comparable to INTG for the prediction of SGA when ROC‐derived cutoffs were used
• Using a 15^th percentile cutoff for Hadlock EFW or 22^nd percentile for INTG EFW may improve the ability of ultrasound to predict SGA

Learn More – Primary Sources:

The Hadlock Method Is Superior to Newer Methods for the Prediction of the Birth Weight Percentile

INTERGROWTH-21st: The International Fetal and Newborn Growth Consortium

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How Accurate are Estimated Fetal Weight Ultrasound Measurements between 23 and 25 Weeks?

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