A prospective pilot study in assessing the accuracy of ultrasound estimated fetal weight prior to delivery.

BACKGROUND

Perinatal mortality and morbidity related to growth restriction and macrosomia are predicted by birthweight. Estimated fetal weight is a surrogate measure for neonatal weight, and accurate measurement of this is central to providing counselling and managing preterm birth.

AIMS

To assess the accuracy of estimated fetal weight (EFW) measured by two sonographers within 1 week of delivery using Hadlock formula.

MATERIALS AND METHODS

Two sonographers independently scanned 150 women with singleton pregnancies, who were booked for elective delivery. The sonographers measured four biometric measurements in estimating fetal weight. The accuracy of EFW compared to the birthweight was examined. We also assessed the sensitivity and specificity for diagnosis of small-for-gestational age (SGA) and large-for-gestational age (LGA) according to the EFW.

RESULTS

Estimated fetal weight was similar to actual birthweight, with a mean percentage difference (SD) of 1.4(7.0) (P = 0.44). The reliability coefficient of EFW compared to actual birthweight was 0.97 (95% CI (0.96, 0.98)). There was no significant difference between the sonographers for EFWs and among the sonographers from the ultrasound scan to delivery interval. The sensitivity and specificity for detection of SGA and LGA were 93.3% and 99.3%, 60% and 95.6%, respectively.

CONCLUSIONS

There is high reproducibility with minimum discrepancy from actual birthweight among sonographers 1 week prior to delivery using Hadlock formula with better prediction of SGA neonates.