Objectives: To evaluate the Cesarean scar defect depth and the residual myometrial thickness with 3-dimensional (3D) sonography concerning interobserver variation. Methods: Ten women were randomly selected from a larger cohort of Cesarean scar ultrasound evaluations. All women were examined 6-16 months after their first Cesarean section with 2D transvaginal sonography and had 3D volumes recorded. Two observers independently evaluated “off-line” each of the 3D volumes stored. Residual myometrial thickness (RMT) and Cesarean scar defect depth (D) was measured in the sagittal plane with an interval of 1mm across the entire width of the endometrium. RMT was defined as the shortest distance from the scar defect to the uterine serosa among all RMT measures, and D was defined similarly as the largest depth of the scar defect extending from the uterine cavity. The median value for RMT and D for each observer as well as the median difference in RMT and D between the two observers was calculated. Results: The median value of RMT was 6.0 mm in observer 1 (range 2.0-7.8) and 5.7 mm in observer 2 (range 2.1-7.6). Median difference in RMT between the two observers was 1.3 mm (range 0.1-3.3). The median value of D was 2.6 mm in observer 1 (range 1.2-5.4) and 2.4 mm in observer 2 (range 1-4.9), and the median difference was 1.0 mm (range 0.3-2.8) between observer 1 and 2. Conclusions: The 3D interobserver variation concerning measures of RMT and D seems good. The role of 3D sonography in evaluations of Cesarean section scar size and residual myometrium needs further investigation.
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22th World Congress on Ultrasound in Obstetrics and Gynecology, 2012