Prediction of fetal macrosomia: Effect of sonographic fetal weight-estimation model and threshold used

N. Melamed*, Y. Yogev, I. Meizner, R. Mashiach, J. Pardo, A. Ben-Haroush

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Objective To compare the accuracy of 21 sonographic fetal weight-estimation models and abdominal circumference (AC) as a single measure for the prediction of fetal macrosomia (> 4000 g) using either fixed or optimal model-specific thresholds. Methods A total of 4765 sonographic weight estimations performed within 3 days prior to delivery were analyzed. The predictive accuracy of 21 published sonographic fetal weight-estimation models was calculated using three different thresholds: a fixed threshold of 4000 g; a model-specific threshold obtained from the inflexion point of the receiver-operating characteristics (ROC) curve; and a model-specific threshold associated with the highest overall accuracy. Cluster analysis was used to determine whether a certain combination of fetal biometric indices is associated with a higher predictive accuracy than others. Results For a fixed threshold of > 4000 g, there was considerable variation among the models in sensitivity (range, 13.6-98.5%) and specificity (range, 63.6-99.8%) for fetal macrosomia. Use of the threshold derived from the inflexion point of the ROC curve decreased the intermodel variation to a minimum (sensitivity, 84.4-91.4%; and specificity, 79.5-86.3%). Even when this optimal model-specific threshold was applied, models based on three to four biometric indices were more accurate than were models based on only two biometric indices or on AC as a single measure (P = 0.03). Conclusions Sonographic fetal weight-estimation models based on three to four biometric indices appear to be more accurate than are models based on two indices or on AC as a single measure, for the diagnosis of macrosomia. In these cases, the use of an optimal, model-specific threshold is associated with a higher degree of accuracy than is the uniform use of a fixed threshold of an estimated weight of > 4000 g.

Original languageEnglish
Pages (from-to)74-81
Number of pages8
JournalUltrasound in Obstetrics and Gynecology
Volume38
Issue number1
DOIs
StatePublished - Jul 2011

Keywords

  • accuracy
  • comparison
  • macrosomia
  • models
  • prediction

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