Risk factors for formation of uterine scar defect after cesarean section: parameters of reproductive health disorders

In recent decades, the global rate of cesarean sections (CS) has been steadily increasing, with Ukraine reporting rates of up to 26% over the past five years. The increased rate of abdominal deliveries has negative outcomes, particularly, a rising number of women of reproductive age with uterine scars who plan future pregnancies. That is why the problem of postoperative scar capacity and the impact of the “operated uterus” on the course of future pregnancies, childbirth and the general reproductive health of the woman is relevant.The objective: to assess the reproductive health parameters of women after CS, identify the most probable factors contributing to uterine scar defect, and stratify the risk of reproductive disorders.Materials and methods. A total of 122 patients were examined: 92 women with a postoperative uterine scar after CS (main group) and 30 healthy women (control group) who were observed for male infertility. The main group was divided into two subgroups: subgroup A included 50 women (54.3%) with a history of abdominal delivery who presented with symptoms of the “post-cesarean uterus syndrome”, and subgroup B consisted of 42 patients (45.7%) also with a history of abdominal delivery, but without clinical symptoms of “post-cesarean uterus syndrome”. An analytical assessment of medical history, complaints, and the results of instrumental diagnostic methods (ultrasound examination (US) and diagnostic hysteroscopy) was conducted.Results. Using transvaginal US, isthmocele was diagnosed 2.9 times more frequently in patients of subgroup A (odds ratio (OR) = 5.98, р < 0.001). The formation of a “niche” was associated with the parity of abdominal delivery (OR = 3.48, р < 0.04), short intergenerational interval (OR = 3.38, р < 0.03), a phenotype of undifferentiated connective tissue dysplasia (OR = 5.64, р < 0.04), chronic endometritis (OR = 3.06, р < 0.04); the additional predictors were adenomyosis and iatrogenic endometriosis (OR = 5.06, р < 0.02). Diagnosis of the “niche” in more than half of the cases in subgroup A was accompanied by the clinical picture of the “post-cesarean uterus syndrome”, which was manifested by symptoms of menstrual cycle disorders, dysmenorrhea, chronic pelvic pain, and urogenital disturbances predominated. Evaluation of the minimum myometrial thickness showed that in subgroup A only 7 (14.0%) patients had no sonographic signs of isthmocele, while in subgroup B – half of the cases (21–50.0%) (OR = 6.14; 95% confidence interval [2.26–16.73]; χ2 = 12.32; p < 0.001), which formed a more pronounced clinical picture of the symptom complex of “post-cesarean uterus syndrome” in patients in subgroup A.Conclusions. The frequency of symptoms that form the “post-cesarean section uterus syndrome” demonstrates the following structure: menstrual cycle disorders (68.0%, p < 0.001), dysmenorrhea (42.0%, p < 0.03), abnormal uterine bleeding (30.0%, p < 0.01), secondary infertility (38.0%, p < 0.04), chronic pelvic pain (24.0%, p < 0.02), and urogenital disorders (18.0%, p < 0.04). The results of evaluating obstetric complications indicate that an increased frequency of fetal prematurity by 5.0 times (24.0%, p < 0.03), low placentation and placenta previa by 3.7 times (26.0%, p < 0.04), as well as the growth of placental tissue in the scar area, which was accompanied by uterine bleeding (14.0%, p < 0.03). The OR calculation allowed predicting an increased risk of reproductive disorders in cases of sonographically diagnosed uterine scar defect with a minimal remaining myometrial thickness < 2.5 mm, by 5.8 times (OR = 5.83, р < 0.001). In cases of an extremely thinned postoperative scar defect (residual myometrial thickness ≤ 2.0 mm), the risk of not only reproductive health disorders but also severe obstetric and postoperative complications, increased (OR = 21.67, р < 0.001).