Comparison of Placental Volume in Early Pregnancy Using Multiplanar and VOCAL Methods

Abstract

In this study we aimed to compare the multiplanar and VOCAL (Virtual Organ Computer-aided AnaLysis) methods in the evaluation of placental volume during the first trimester of pregnancy. This was a prospective cross-sectional study involving 37 pregnant women between 7 and 10 weeks of gestation. All volumetric measurements were performed by a single examiner using an endocavitary volumetric probe (3D5-8EK). Placental volume was measured on three-dimensional ultrasound by the VOCAL method using 12° and 30° rotational angles and by the multiplanar method using sequential sections of the placenta obtained at intervals of 1.0 mm. Pearson's correlation coefficient ( r) was used to evaluate the relation between placental volume and gestational age. The interclass correlation coefficient (ICC), paired Student's t-test ( P) and Bland–Altman plot were used to compare both methods. There was a strong correlation between placental volume and gestational age ( r = 0.791 for VOCAL 12°, r = 0.801 for VOCAL 30° and r = 0.783 for multiplanar). There was a strong correlation between placental volume measured by the VOCAL 12° and the VOCAL 30° (ICC = 0.994, confidence interval [0.998; 0.997]) and the multiplanar methods (ICC = 0.991, confidence interval [0.983; 0.995]). First trimester placental volume measurements obtained using the multiplanar and VOCAL methods are concordant.