Placental and spiral artery volume and gray-scale value assessment via 3-dimensional sonography in the second...

Extreme placental size has been associated with abnormal pregnancy outcomes. The purpose of this study was to establish normal values for placental and spiral artery volume and gray-scale value as assessed via 3-dimensional (3D) sonography in the second trimester.

The entry criterion was a documented singleton pregnancy at 14-25 weeks' gestation. Patients with normal pregnancy outcome were stratified into 6 subgroups representing 2-week intervals. Automatic 3D sonographic acquisition of the placental and spiral artery volume and gray-scale value, expressed as a percentage, was obtained.

Out of 199 patients with normal pregnancy outcome, the placental volume was between 77.7 and 213.9 cm(3) and the gray-scale value was between 28.6 and 29.2 cm(3) (depending on gestational age). The spiral artery volume adjacent to placenta was between 47.9 and 108.7 cm(3), and the gray-scale value was between 27.5 and 29.5 cm(3). Statistical analysis in each subgroup of patients revealed a significant difference between placental and spiral artery volumes but no difference when the gray-scale value was compared.

We defined normal placental and spiral artery volume and gray-scale value in the second trimester of normal pregnancy using 3D sonography.