Features of the structure of uterine scars after cesarean section

Aim of the study. To study the morphological structure of scar tissue in patients with uterine scar defects (USD) after cesarean section (CS), as well as the effect of changes in mechanical stress in the area of the newly formed scar after metroplasty. Material and methods. A comparative prospective study was performed, which included 113 patients with USD after CS operations interested in repeat pregnancy. All patients underwent metroplasty with laparoscopic access, including 61 patients — using the standard technique; 52 — using the method with shortening of the round ligaments of the uterus. In all cases, a histological examination of the excised scar tissue was performed; in 18 patients (5 without undifferentiated connective tissue dysplasia (UCTD), 13 with UCTD), a histochemical examination of the excised scar tissue was performed; in 7 patients, a molecular genetic examination of endometrial biopsies from the area of the newly formed scar after metroplasty was performed. Results. As a result of the histological examination, it was established that the scar tissue of patients with UCTD is morphologically represented in 76.9% by fibrous-muscular tissue, in 14.4% by fibrous tissue, and in 8.7% by fibrous-muscular tissue with inclusion of fat. When assessing the structure of scar tissue in patients with UCTD and without UCTD, a number of differences were revealed. In the samples obtained from patients with uCTD, a more chaotic arrangement of collagen fibers was noted, their area was 57.15% smaller (p=0.01), the collagen content was 52.5% lower (p<0.0001). When assessing the effect of the number of CS operations in the anamnesis on the structure of scar tissue in patients with uCTD, it was found that with an increase in the number of CS operations to 2, a progressive decrease in the number of collagen fibers by 39.2% (p=0.0454), as well as an increase in the severity of mucoid swelling (p=0.037) were noted. Molecular genetic research revealed differences in gene expression in the endometrial biopsy after metroplasty with and without shortening of the round ligaments. 26 genes belonging to different functional groups were identified, the mRNA levels of which differed in the endometrial samples of patients after metroplasty with and without shortening of the round ligaments. Conclusion. Undifferentiated connective tissue dysplasia and an increase in the number of cesarean sections in anamnesis in combination with undifferentiated connective tissue dysplasia play a pronounced negative role in the pathogenesis of the formation of uterine scar defects after cesarean section. Differences in gene expression revealed in endometrial biopsies from the scar area after metroplasty with and without shortening of the round ligaments of the uterus indirectly confirm the effect of changes in mechanical stress in the area of the newly formed scar on the reparative process.