estimated fetal weight
Also written as: EFW — Estimated Fetal Weight
Ultrasound-calculated approximation of fetal weight using biometric measurements.
Full Definition
Estimated fetal weight (EFW) is a calculated prediction of fetal weight derived from ultrasound biometric measurements including biparietal diameter, head circumference, abdominal circumference, and femur length. Various formulas are used for this calculation, with the Hadlock formula being most commonly employed. EFW is typically reported with a margin of error of ±10-15% and is used to assess fetal growth, plan delivery method, and counsel patients about potential complications. Accuracy decreases with increasing gestational age and in cases of oligohydramnios or obesity.
Usage
Usage note: Always specify gestational age and percentile when reporting; note margin of error.
In Context
- "The estimated fetal weight was 2,800 grams at 36 weeks." — Ultrasound report
- "EFW suggested possible macrosomia requiring delivery planning." — High-risk pregnancy consultation