The second step was to measure the thickness of the LUS using 2D ultrasound. View of the LUS was obtained in the mid-sagittal plane and the view was magnified looking for the thinnest area of the LUS. Also, the LUS was examined in a lateral view to detect any apparent rupture, ballooning or funneling. The measurement was taken with the cursors at the urine-Urinary bladder interface and the amniotic fluid -decidua interface after sufficient magnification and measurement was taken to the nearest tenth of millimeter. The numeric display was covered during the examination to avoid bias when performing the 3D measurement in the next step. Three measurements were taken and the least measurement was recorded.