Reference ranges for fetal cardiac, ventricular and atrial relative size, sphericity, ventricular dominance, wall asymmetry and relative wall thickness from 18 to 41 weeks of gestation

OBJECTIVE To construct nomograms for fetal cardiac, ventricular and atrial relative size and geometry using a low-risk population. METHODS Prospective cohort study including 602 low-risk singleton pregnancies undergoing a fetal echocardiography from 18 to 41 weeks of gestation to assess cardiac, atrial and ventricular relative size and sphericity, ventricular dominance, wall asymmetry and relative wall thickness. Intra- and inter-observer reproducibility were evaluated by calculating the interclass correlation coefficient (ICC). In order to construct reference ranges across pregnancy, parametric regressions were tested to model each measurement against gestational age and estimated fetal weight for cardio-thoracic ratio; atrial-to-heart ratios; ventricular-to-heart ratios; heart, ventricular and atrial sphericity indices; right-to-left basal and midventricular ratios; septal-to-free wall thickness ratios and relative wall thicknesses. RESULTS Fetal cardiac, ventricular and atrial morphometry for assessing relative size and geometry could be successfully obtained in \u003e95%, with good intra- and interobserver reproducibility (ICC 0.63-0.83). Cardio-thoracic ratio and ventricular right-to-left ratio showed a modest increase throughout gestation. Atrial-to-heart and ventricular-to-heart ratios, atrial sphericity indices and septal-to-free wall thickness ratios were constant with gestational age. Ventricular sphericity indices and relative wall thicknesses tended to decrease at the end of gestation. Nomograms across gestation were constructed for all echocardiographic parameters described. CONCLUSIONS The assessment of cardiac, ventricular and atrial relative size and geometry is feasible and reproducible in the fetus. We provide standardized reference ranges throughout gestation, enabling the accurate assessment of cardiac remodelling patterns during fetal life. The immediate application of these measurements may be in the research field, but they further represent a very useful tool in clinical ultrasonographic evaluation enabling to establish a consensus-based nomenclature for fetal cardiac findings, above all in pathological scenarios and stablishing reference ranges for abnormality detection and monitoring. This article is protected by copyright. All rights reserved.