Am J Obstet Gynecol MFM. 2023 Aug 11:101123. doi: 10.1016/j.ajogmf.2023.101123. Online ahead of print.
ABSTRACT
BACKGROUND: The estimation of fetal weight (EFW) by fetal magnetic resonance imaging (MRI) is a simple and rapid method, with a high sensitivity to predict birthweight (BW) in comparison to ultrasound (US). Several national and international growth charts are currently in use but there is substantial heterogeneity among these charts due to: variations in the selected populations from which they were derived, different methodologies and statistical analysis of data.
OBJECTIVE: The purpose of this study was to compare the performance of MRI and US for the prediction of BW using three commonly used fetal growth charts: INTERGROWTH-21st (IG-21) project, World Health Organization (WHO), and Fetal Medicine Foundation (FMF).
STUDY DESIGN: Data derived from a prospective, single center, blinded cohort study that compared the performance of MRI and US between 36+0/7 to 36+6/7 weeks of gestation (WG) for the prediction of BW ≥ 95th percentile was reanalyzed. EFW were categorized as > or < 5th, > or < 10th, > or < 90th, and > or < 95th percentile according to the three growth charts. BW was similarly categorized according to the BW standards of each chart. The performances of US and MRI for the prediction of BW < 5th, < 10th, > 90th, and > 95th percentile using the different growth charts were compared. Data were analysed with R software version 4.1.2. The comparison of sensitivity and specificity was done by McNemar and exact binomial tests. A p-value < 0.05 was considered as statistically significant.
RESULTS: 2378 women were eligible for final analysis. US and MRI were performed at a median gestational age of 36+3/7 WG, delivery occurred at a median gestational age of 39+3/7 WG, and median BW was 3380 grams. The incidences of BW < 5th and < 10th percentiles were highest with the FMF chart and lowest with the IG-21 chart, whereas the incidences of BW > 90th and > 95th percentiles were lowest with the FMF chart and highest with the IG-21 chart. The sensitivity of MRI with an EFW > 95th percentile in the prediction of BW > 95th percentile was significantly higher than that of US across the three growth charts, however, its specificity was slightly lower than that of US. In contrast, the sensitivity of MRI with an EFW <10th percentile for predicting BW <10th percentile was significantly lower than US in the IG-21 and FMF charts, whereas the specificity and positive predictive value (PPV) of MRI were significantly higher than US for the three charts. Findings for the prediction of BW > 90th percentile were close to those of BW > 95th percentile, and findings for the prediction of BW < 5th percentile were close to those of BW < 10th percentile.
CONCLUSION: The sensitivity of MRI is superior to US for the prediction of large for gestational age (LGA) fetuses and inferior to US for the prediction of small for gestational age (SGA) fetuses across the three different growth charts. The reverse is true for the specificity of MRI in comparison to the specificity of US.
PMID:37574047 | DOI:10.1016/j.ajogmf.2023.101123
