Comparison of ultrasonic diagnosis of cesarean scar defects at different timepoints following cesarean section

Cesarean scar defect (CSD) is a potential complication following cesarean section (CS), which has significant clinical implications, and is usually clinically diagnosed by ultrasound. However, the optimal timing for ultrasound diagnosis of CSD after CS has not been well established. This study aimed to evaluate the appropriate time for the diagnosis of CSD after CS by ultrasonography.

The prospective study involved 120 women who delivered by elective CS with single birth and term birth from January 2021 to June 2022. Sample enrollment was consecutive in the study. Each woman underwent 3 ultrasound examinations for CSD diagnosis at 6 weeks, 6 months, and 12 months postpartum according to a modified Delphi method. The ultrasound indicators about the incision situation were recorded and statistically analyzed. Paired 4-fold table chi-square test was used to evaluate the consistency between the 3 diagnoses. The diagnostic sensitivity and specificity were calculated using a 4-cell table. According to whether the diagnosis was consistent to that at 6 or 12 months, the 120 cases at week 6 were separated into a consistent group and inconsistent group for statistical evaluation of the ultrasound indicators. Additionally, the menstrual duration of the included women was also recorded to analyze the correlation to ultrasound indicators of CSD at 6 months postpartum using the Person correlation coefficient.

The included 120 women were divided into normal (3-7 days, n=52) and prolonged menstrual period (>7 days, n=68) groups. The 2 groups had no statistical differences in age, body mass index (BMI), gestational week of delivery, assisted reproduction rates, or postpartum complications. Among the 120 women, 100, 66, and 61 women were diagnosed as CSD at 6 weeks, 6 months, and 12 months postpartum, respectively. The results indicated that the diagnostic results of 6 weeks were inconsistent with those of 6 or 12 months postpartum, but the last 2 diagnostic results were consistent. The diagnostic sensitivity of 6 months was 100% and the specificity was 91.53% [95% confidence interval (CI): 85.84-95.26%]. Further, significant differences were found in depth of the defect, and the thickness (T) and ratio of residual muscle between the inconsistent group and the consistent group at 6 weeks. The patients could be considered self-recovered from CSD at 6 months when the defect depth was equal to or less than 4.04±0.82 mm at 6 weeks after CS. Additionally, in the CSD group at 6 months, the length (r=0.828, P<0.001), depth (r=0.784, P<0.001), width (r=0.787, P<0.001) of the defect, the T (r=0.831, P<0.001) and ratio of residual muscle (r=0.821, P<0.001) were strongly correlated with menstrual duration.

CSD evaluation at week 6 after CS may cause misdiagnosis or overdiagnosis. The diagnosis of CSD was suggested to be made following 6 months or longer postpartum.