From: Towards more accurate measurement of edge to os distance in low-lying placenta using three dimensional transvaginal ultrasound: an innovative technique
Placental location groups
Mean difference (2D-3D estimate)(mean ± SD) mm
One way ANOVA
Games- Howel Post Hoc test
Direct Anterior/posterior
0.85 ± 0.82
0.000
1
Anterolateral/posterolateral
5.33 ± 5.29
0.001
Lateral
13.59 ± 4.56