2D and 3D Ultrasound Assessment of Cesarean Section Scars and Its Correlation to Intraoperative Findings

Transabdominal ultrasound examination to obtain full obstetric ultrasound report including estimated gestational age, fetal lie, presentation, amniotic fluid volume, placental location with special focus on relation to the uterine scar.

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.

After the entire thickness was measured by 2D ultrasound, 3 D measurement were taken in the mid-saggittal plan using the multiplanar display mode and then moving through the acquired 3-D volume in the saggittal plane till the thinnest area was seen and then measurements were taken.3-D volume dataset was obtained of the LUS by the same operator. The acquired volume was manipulated on the multiplanar display mode, searching for the thinnest part of the LUS avoiding obliquity.

Transvaginal ultrasound examination was done following the transabdominal one. The vaginal probe was inserted into the posterior vaginal fornix with the patient lying supine and the patient's knees are gently flexed and hips are slightly elevated with a pillow. Clear view of the LUS was obtained in the midsagittal plane visualizing the cervical canal to ensure that the view is midline one and avoiding obliquity.

On transvaginal examination the muscular layer of the LUS was clearly seen as hypoechoic line between the hyperechoic uterovesical fold and the decidualized endometrium and the chorioamniotic membranes. The scar area was magnified so the scar occupies at least 75% of the image to ensure consistent and accurate measurements. The thickness of the muscular layer of LUS was taken with the measuring caliber placed at the urinary bladder wall-myometrium interface and the myometrial/ chorioamniotic membrane interface .Three measurements of the LUS were taken, and again, the least measurement was recorded.