Obstetrics
Hadlock Estimated Fetal Weight (EFW Sonographic Biometry)
Calculates Estimated Fetal Weight in grams and lbs from 4-parameter ultrasound biometry (BPD, HC, AC, FL).
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Parameters
Hadlock Estimated Fetal Weight (EFW Sonographic Biometry) Result
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Formula
Log₁₀(EFW) = 1.3596 - (0.00386 × AC × FL) + (0.0064 × HC) + (0.00061 × BPD × AC) + (0.0424 × AC) + (0.0174 × FL)Clinical Pearls
The global standard obstetric sonography algorithm embedded in hospital ultrasound machines worldwide for fetal biometric weight assessment.
Limitations
Ultrasound EFW typically exhibits an inherent error margin of ± 10% to 15%; maternal obesity, oligohydramnios, and multiple gestation may reduce precision.