Fetal weight estimation by automated three-dimensional limb volume model in late third trimester compared to two-dimensional model: a cross-sectional prospective observational study

Abstract

Background Accurate estimation of fetal weight is important for prenatal care and for detection of fetal growth abnormalities. Prediction of fetal weight entails the indirect measurement of fetal biometry by ultrasound that is then introduced into formulae to calculate the estimated fetal weight. The aim of our study was to evaluate the accuracy of fetal weight estimation of Chinese fetuses in the third trimester using an automated three-dimensional (3D) fractional limb volume model, and to compare this model with the traditional two-dimensional (2D) model. Methods Prospective 2D and 3D ultrasonography were performed among women with singleton pregnancies 7 days before delivery to obtain 2D data, including fetal biparietal diameter, abdominal circumference and femur length, as well as 3D data, including the fractional arm volume (AVol) and fractional thigh volume (TVol). The fetal weight was estimated using the 2D model and the 3D fractional limb volume model respectively. Percentage error was defined as (estimated fetal weight - actual birth weight) divided by actual birth weight and multiplied by 100. Systematic errors (accuracy) were evaluated as the mean percentage error (MPE). Random errors (precision) were calculated as ±1 SD of percentage error. The intraclass correlation coefficient (ICC) was used to analyze the inter-observer reliability of the 3D ultrasound measurements of fractional limb volume. Results Ultrasound examination was performed on 56 fetuses at 39.6 ± 1.4 weeks’ gestation. The average birth weight of the newborns was 3393 ± 530 g. The average fetal weight estimated by the 2D model was 3478 ± 467 g, and the MPE was 3.2 ± 8.9. The average fetal weights estimated by AVol and TVol of the 3D model were 3268 ± 467 g and 3250 ± 485 g, respectively, and the MPEs were − 3.3 ± 6.6 and − 3.9 ± 6.1, respectively. For the 3D TVol model, the proportion of fetuses with estimated error ≤ 5% was significantly higher than that of the 2D model (55.4% vs. 33.9%, p < 0.05). For fetuses with a birth weight < 3500 g, the accuracy of the AVol and TVol models were better than the 2D model (− 0.8 vs. 7.0 and − 2.8 vs. 7.0, both p < 0.05). Moreover, for these fetuses, the proportions of estimated error ≤ 5% of the AVol and TVol models were 58.1 and 64.5%, respectively, significantly higher than that of the 2D model (19.4%) (both p < 0.05). The inter-observer reliability of measuring fetal AVol and TVol were high, with the ICCs of 0.921 and 0.963, respectively. Conclusion In this cohort, the automated 3D fractional limb volume model improves the accuracy of weight estimation in most third-trimester fetuses. Prediction accuracy of the 3D model for neonatal BW, particularly < 3500 g was higher than that of the traditional 2D model.

Establishing Chinese Fetal Growth Standards: Why and How

“…A multicenter study indicated that the inclusion of automated FLV measurements improved the proportion of correctly classified birthweight ± 10% in >80% of cases than 73.8% for the INTERGROWTH-21 st model 64 . For Chinese fetuses in the third trimester, particularly newborns weighing <3500 g, the percentage of estimated error ≤ 5% using the automated limb volume estimation software (58.1% for AVol model and 64.5% for TVol model) was significantly higher than that of the traditional 2D model (19.4%) 68 …”

“…introduced the concept of FLV, which provided a new way of evaluating soft tissue for weight prediction 65 . Since then, numerous studies have shown that a combination of 2D and 3D parameters can improve the precision of EFW 64,66–68 . During the second and third trimesters of pregnancy, incorporation of 3D data, such as fractional arm volume (AVol) or fractional thigh volume (TVol), into estimation models reduced the random error to 6.6% 66 .…”

“…65 Since then, numerous studies have shown that a combination of 2D and 3D parameters can improve the precision of EFW. 64,[66][67][68] During the second and third trimesters of pregnancy, incorporation of 3D data, such as fractional arm volume (AVol) or fractional thigh volume (TVol), into estimation models reduced the random error to 6.6%. 66 By comparison, the random errors of the original Hadlock model and a modified Hadlock model were 8.5% and 7.6%, respectively.…”

Comparison of diagnostic value of two-dimensional ultrasound and clinical examination in fetal weight estimation

“…This indicates the high accuracy of fetal weight estimation by ultrasound, and this finding is consistent with the results of previous studies. [ 14 15 16 ]…”

Comparison of two‐dimensional (2D) and three‐dimensional (3D) ultrasonography for gestational ageing in the early to mid‐pregnant bitch

“…4D ultrasound), generating continuous 3D volume data sets and providing functional and dynamic data in three dimensions (Hildebrandt et al., 2009 ; Mattoon et al., 2002 ). Both 3D and 4D volume ultrasonography are well established in human obstetrics and gynaecology (Merz & Welter, 2005 ) and have been reported to offer the advantage to allow the analysis of a number of clinical conditions including congenital disorders or foetal deformities even allowing the demonstration of subtle foetal defects, foetal gender determination, gestational age and birth weight assessment (Kotoyori et al., 2012 ; Merz & Pashaj, 2017 ; Wu et al., 2021 ; Youssef et al., 2011 ). Their establishment in human medicine is also based on an important emotional aspect for the parents, allowing them to see a concrete 3D reconstruction of their babies, helping them to understand and accept possible existing malformations, or to reassure them of the absence of foetal abnormalities (Merz & Pashaj, 2017 ; Merz & Welter, 2005 ).…”