Repeatability of estimated fetal weight: Comparison between MRimaging versus 2D ultrasound in at-and near-term patients

Introduction: Our aim was to evaluate the intra-and inter-observer variability and the impact of operatorexperience on the estimation of fetal weight (EFW) as measured by 2-dimensional ultrasound (2D-US) and magnetic resonance (MR) imaging. Material and methods: We estimated fetal weight in 46 singleton pregnancies at 35.6-41.4 weeks gestation using 2D-US according to the Hadlock formula and using MR imaging according to the equationdeveloped by Baker. Each examination was performed twice, once by an inexperienced operator andonce by an experienced operator. The MR-EFW was derived from the planimetric measurement of fetalbody volume (FBV) using an assisted semi-automated method. Intra-and inter-observer variability wasevaluated by Bland-Altman analysis. Regression analysis was used to investigate the effect of maternalBMI, delivery weight, diabetes and fetal gender on the differences in US-EFW between the inexperiencedand experienced operators. Results: US-EFW showed higher intra-observer variability than MR-EFW, irrespective of operator experience. The 95% limits of agreement of MR were narrower compared with those of the US measurements. Similarly, US-EFW showed higher inter-observer variability than MR-EFW. MR-EFW improvement over2DUS for the limits of agreement was 77.9% for intra-observer variability and 74.5% for inter-observervariability. Regression analysis showed that the differences between US-EFW measurements were notrelated to any of the tested variables. Conclusions: Operator experience has a marginal impact on the variability of US-EFW and no impact onMREFW variability. The variability in US-EFW measurements is unpredictable. (C) 2017 Elsevier B.V. All rights reserved.