Prediction of large for gestational age by various sonographic fetal weight estimation formulas—which should we use?

• Published in: Journal of perinatology Vol. 37; no. 5; pp. 513 - 517
• Main Authors: Aviram, A, Yogev, Y, Ashwal, E, Hiersch, L, Hadar, E, Gabbay-Benziv, R
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.05.2017; Nature Publishing Group
• Subjects: 692/700/139; 692/700/1421; Abdomen; Accuracy; Adult; Age; Biometrics; Birth size; Birth Weight; Cohort analysis; Diameters; Euclidean geometry; Female; Femur; Fetal Weight; Fetus; Fetus - diagnostic imaging; Fetuses; Gestational Age; Hospitals; Humans; Infant, Newborn; Infant, Small for Gestational Age; Israel; Likelihood ratio; Male; Medicine; Medicine & Public Health; Methods; Neonates; Obstetrical research; original-article; Pediatric Surgery; Pediatrics; Predictions; Pregnancy; Random errors; Retrospective Studies; Sensitivity and Specificity; Tertiary Care Centers; Ultrasonic imaging; Ultrasonics in obstetrics; Ultrasonography, Prenatal - methods; Ultrasonography, Prenatal - standards; Variation; Womens health; Israel; Tel Aviv Israel
• ISSN: 0743-8346; 1476-5543
• DOI: 10.1038/jp.2017.5

Objective: As sonographic estimation of fetal weight (EFW) carries substantial impact, especially in large-for-gestational-age (LGA) neonates, we aimed to compare the accuracy of various formulas for prediction of LGA neonates. Study Design: Retrospective cohort study of singleton gestations at term, with EFW up to 7 days before delivery (2007 to 2014). Small-for-gestational-age neonates were excluded. LGA prediction for various formulas was evaluated by: (i) measures of performance (sensitivity, specificity, etc.); (ii) systematic and random errors (SE and RE) and the proportion of estimates (POEs) exceeding 10% of actual birth weight. Best performing formula was defined as the one with the lowest Euclidean distance [=square root of (SE 2 +RE 2 )]. Results: Out of 62 102 deliveries, 7996 met inclusion criteria, of which 1618 neonates were LGA (22%). There was a considerable variation in sensitivity (74.6±16.3%, 23.5% to 99%), specificity (86.3±10.6%, 51.7% to 99.6%), positive predictive value (64.9±12.4%, 35.6% to 93.8%), positive likelihood ratio (LR; 9.3±10.9, 2.1 to 54.2) and negative LR (0.3±0.16, 0.02 to 0.8), a mild variation in the negative predictive value (92.9±3.7%, 82.3% to 99.5%) and a minimal variation in the area under the curve (94.3%, 93.0 to 95.1; mean±s.d., range for all). Absolute SE was higher for the LGA group in 11/20 formulas (55%). The RE and POE were lower in 19/20 (95%) and 14/20 (70%) for the LGA neonates, respectively. Conclusion: There is a wide variation in EFW formulas performance for detecting LGA. Hadlock’s formula (1985) combining abdominal circumference, femur length and biparietal diameter ranked highest.