Comparison of sonographic fetal weight estimation formulas in patients with preterm premature rupture of membranes

Abstract

Background: Estimation of fetal weight (EFW) by ultrasound is useful in clinical decision-making. Numerous formulas for EFW have been published but have not been validated in pregnancies complicated by preterm premature rupture of membranes (PPROM). The purpose of this study is to compare the accuracy of EFW formulas in patients with PPROM, and to further evaluate the performance of the most commonly used formula-Hadlock IV. Methods: A retrospective cohort study of women with singleton gestations and PPROM, admitted to a single tertiary center between 2003-2017 from 22 0/7-33 0/7 (n=565). All women had an EFW within 14 days of delivery by standard biometry (biparietal diameter, head circumference, abdominal circumference and femur length). The accuracy of previously published 21 estimated EFW formulas was assessed by comparing the Pearson correlation with actual birth weight, and calculating the random error, systematic error, proportion of estimates within 10% of birth weight, and Euclidean distance. Results: The mean gestational was 26.8±2.4 weeks at admission, and 28.2±2.6 weeks at delivery. Most formulas were strongly correlated with actual birth weight (r>0.9 for 19/21 formulas). Mean systematic error was-4.30% and mean random error was 14.5%. The highest performing formula, by the highest proportion of estimates and lowest Euclidean distance was Ott (1986), which uses abdominal and head circumferences, and femur length. However, there were minimal difference with all of the rst 10 ranking formulas. The Pearson correlation coe cient for the Hadlock IV formula was strong at r=0.935 (p<0.001), with 319 (56.5%) of measurements falling within 10%, 408 (72.2%) within 15% and 455 (80.5%) within 20% of actual birth weight. This correlation was unaffected by gender (r=0.936 for males, r=0.932 for females, p<0.001 for both) or by amniotic uid level (r=0.935 for mean vertical pocket <2 cm, r=0.943 for mean vertical pocket ≥2cm, p<0.001 for both). Conclusions: Most formulas accurately calculated EFW in patients with PPROM, but the Ott (1986) formula ranked highest, thus it may be the preferred formula to use in this population.

Prediction of Small-For-Gestational-Age Neonates at 33-39 Weeks’ Gestation in China: Logistic Regression Modeling of The Contributions of Second- and Third-Trimester Ultrasound Data and Maternal Factors

“…The combination of AC, FL, BPD and HC yields a variety of formulas for calculating EFW [20]. According to the ultrasonic data from 33 +0 -39 +6 weeks' gestation, EFW was calculated respectively and nally converted into EFW MoM values (EFW-M) according to GA. ROC curve analysis showed that the formula created by Hadlock (1985) based on AC, FL and HC was the most suitable for this paper (Data not displayed).…”