Effect of cervical changes on the cesarean scar area and niche formation after preterm and term cesarean sections.

Objective: The purpose of this study is to assess the scar area and niche formation after cesarean section in women who had preterm or term deliveries and underwent cesarean section at various stages of labor.

Method: This prospective cohort study consists of cases who underwent the first cesarean section for different obstetric reasons. The patients were divided into four groups regarding gestational age and cervical dilatation. After a cesarean section, all patients were called for vaginal ultrasonography control at 12 weeks. The location of the scar and the presence of a niche were evaluated. The residual (RMT), proximal, and distal myometrial thicknesses were evaluated where the scar and niche were located.

Results: A total of 87 cases were included in the study. There was no difference in the prevalence of niche between the groups (p > 0.05). RMT and proximal and distal myometrial thickness were not different between the 37 ≥ week and 37 < week groups, while RMT and proximal and distal myometrial thickness were significantly lower in women with active labor (p =0.001, p= 0.006, p =0.016). The location of the scar was the isthmus at 37 weeks and above (p= 0.002), it was in the cervical canal in the group below 37 weeks (p= 0.017).

Conclusion: The gestational week and cervical changes did not affect the prevalence of the niche. In cases of active labor and preterm deliveries, the CS scar defect was located in the cervical canal; however, in cases of term deliveries, it was located in the isthmic area.