Reference intervals for fetal heart volume from 3-dimensional sonography using the Extended Imaging Virtual Organ Computer-Aided Analysis Method at Gestational Ages of 20 to 34 Weeks

Objectives-The purpose of this study was to establish the reference range for fetal heart volume from 3-dimensional (3D) sonography using the extended imaging virtual organ computer-aided analysis method. Methods-The fetal heart volume was measured in 303 normal singleton pregnancies at gestational ages of 20 to 34 weeks using 3D sonography. The extended imaging virtual organ computer-aided analysis method was used to obtain a sequence of 10 parallel symmetric sections through the heart, according to examiner-determined limits (the apex at one extremity and the connection to the great vessels at the other). Heart contours were drawn manually in all sections to obtain the 3D volume measurement, which was provided automatically by the software. Normal z scores and percentile reference ranges for each gestational age were constructed. Results-The fetal heart volume increased with gestational age. The mean values were 3.09 mL at 20 weeks, 9.18 mL at 26 weeks, and 24.89 mL at 34 weeks, according to the following formulas: fetal heart volume (mL) = 18.0076 - 2.1005 × gestational age + 0.0677 × gestational age2 (R2 = 0.922); and SD (mL) = (4.5038 - 0.4281 × gestational age + 0.0114 × gestational age2) × -1.495808 (R2 = 0.922). Conclusions-A reference range for fetal heart volume using the 3D sonographic extended imaging virtual organ computer-aided analysis method at gestational ages of 20 to 34 weeks was established.