title: Prediction of Small for Gestational Age: Accuracy of Different Sonographic Fetal Weight Estimation Formulas.
abstract: OBJECTIVE
  To compare the accuracy of various sonographic estimated fetal weight (sEFW) formulas for the prediction of small for gestational age (SGA) neonates.
  
  
  METHODS
  A retrospective analysis of 6,126 fetal biometrical measurements performed within 3 days of delivery. SGA prediction was evaluated for various sEFW formulas by calculating the sensitivity, specificity, positive/negative predictive value (PPV/NPV), likelihood ratio (+LR/-LR), overall accuracy and area under the receiver operating characteristic curve (AUC). Systematic error, random error, proportion of estimates >10% of birth weights, actual and absolute weight differences were compared between SGA and non-SGA neonates.
  
  
  RESULTS
  Overall, 638 (10.4%) neonates were SGA. There was considerable variation among formulas in sensitivity (mean ± SD, 62 ± 14.4%; range, 32.4-91.2), PPV (72.5 ± 10.7%; 45.8-95.6) and +LR (24.2 ± 10.9; 7.2-57.3), mild variation in specificity (96.6 ± 2.7%; 87.4-99.4), NPV (94.6 ± 5.3%; 72.2-98.9) and -LR (0.4 ± 0.1; 0.1-0.7) and minimal variation in AUC (mean, 0.93; range, 0.91-0.93). The majority of formulas had a lower accuracy for the SGA neonates, with systematic error and random error ranging from -4.2 to 14.3% and from 8.4 to 12.9% for SGA, and from -8.7 to 16.1% and from 7.2 to 10.5% for non-SGA, respectively.
  
  
  CONCLUSIONS
  sEFW formulas differ in their accuracy for SGA prediction. In our population, the most accurate formula for SGA prediction was Hadlock's formula utilizing femur length, abdominal and head circumference.
authors.affiliation: Helen Schneider Hospital for Women, Rabin Medical Center, Petach-Tikva, Israel.
authors.forename: Rinat
authors.initials: R
authors.lastname: Gabbay-Benziv
authors.forename: Amir
authors.initials: A
authors.lastname: Aviram
authors.forename: Ron
authors.initials: R
authors.lastname: Bardin
authors.forename: Eran
authors.initials: E
authors.lastname: Ashwal
authors.forename: Nir
authors.initials: N
authors.lastname: Melamed
authors.forename: Liran
authors.initials: L
authors.lastname: Hiersch
authors.forename: Arnon
authors.initials: A
authors.lastname: Wiznitzer
authors.forename: Yariv
authors.initials: Y
authors.lastname: Yogev
authors.forename: Eran
authors.initials: E
authors.lastname: Hadar
mesh_terms: D000005:Abdomen / Q000000981:diagnostic imaging; D001699:Biometry; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D020567:Fetal Weight; D005865:Gestational Age; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D007236:Infant, Small for Gestational Age; D008297:Male; D011237:Predictive Value of Tests; D011247:Pregnancy; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000592:standards*