Morphology of the cesarean section scar in the non-pregnant uterus after one elective cesarean section

Abstract

Objectives: A growing number of studies suggest that the incomplete healing of the CS scar in the uterus increase the risk of uterine dehiscence or rupture during subsequent pregnancies. Thus, the factors that affect wound healing should be evaluated. We aimed to determine whether the morphology of the CS scar in non-pregnant women after one elective CS was affected by the site of the uterine incision, uterine flexion, maternal age, and fetal birth weight.

Material and methods: 208 non-pregnant women were invited for participation in the study, but only 101 of them met inclusion criteria. Standardized scar parameters (residual myometrial thickness (RMT), depth (D) and width (W) of the hypoechoic niche) were measured using ultrasonography at least 6 weeks after the CS.

Results: Scar defect was detected in 26 of 101 subjects. Women without scar defect had significantly higher RMT values (1.87 vs. 0.87), lower newborn birth weight (3127 g vs. 3295 g), and higher scar location above the internal cervical os (62% vs. 16%), than those with scar defect. Maternal age was significantly correlated with D value (R = 0.40). Uterine retroflexion was significantly correlated with a larger D value (R = 0.63) and a larger D/RMT ratio (R = 0.24).

Conclusions: In low-risk women who have undergone one elective CS, several risk factors are associated with development of the scar defect, but only scar location can be modified during surgery. Future research is needed to determine whether a relatively higher incision location in the uterus can ensure optimal healing of the CS scar.

Keywords: cesarean section scar; residual myometrial thickness; risk factors of scar defect; scar defect; scar morphology; ultrasonography; uterine scar.