Background
Over the last several decades, the incidence of delivery via cesarean section (C-section) has increased around the world [
1,
2]. Approximately two-thirds of women in Chinese cities selected cesarean section delivery between 1990 and 2002 [
3]. An investigation of 39 hospitals in China indicated that the incidence of C-Section without indication was 24.553% [
4]. It has been reported that many patients who underwent C-section developed C-section scar diverticulum (CSD) after surgery [
5]. The prevalence of a niche ranged from 24 to 70% when assessed by transvaginal sonography [
6] and 19.4 to 88% according to symptom [
7]. The correlation between number of C-section and increased risk of CSD hasn’t been figured out yet though, only few references considered multiple CSs as probable risk factors [
6]. CSD can result in long-term complications, such as prolonged menstrual bleeding (the menstrual cycle is more than seven days), C-section scar ectopic pregnancy, dyspareunia, dysmenorrhea and chronic pelvic pain [
8,
9]. Accumulation of blood in the cesarean scar defect can cause inflammation, influence the mucus quality and make an adverse environment for embryo implantation. As a result, patients suffered the pain of secondary infertility [
10‐
12]. Moreover, C-section scar ectopic pregnancy can increase the incidence of uterine scar rupture, which threatens both the life of the neonate and mother [
13]. Furthermore, many reports have demonstrated that postmenstrual bleeding caused by CSD is the most typical manifestation, which severely affects the quality of life of patients [
14,
15].
No clinical guidelines have been issued for the treatment of CSD based on the thickness of the remaining muscular layer (TRM) or/and prolonged menstrual bleeding. Surgical treatment is a reasonable management approach for CSD since medical therapy is not consistently effective. Many surgical treatments have been reported [
16,
17], such as endometrial ablation [
18]. hysteroscopic surgery [
19], vaginal surgery [
1], and laparoscopic surgery [
13,
20]. In previous study, we reported that vaginal repair of CSD is a very effective surgery for repairing anatomical defects and reducing the number of menstruation days [
21]. Though Tulandi’s meta-analysis quotes menstruation days improvement in 89 to 93.5% of patients with CSD after vaginal repair surgery [
22], however, only 28.2% of cases experienced a reduction in the number of menstruation days to less than 7 according the previous study [
21]. The results confirmed that many CSD patients are difficult to cure, which severely affects the quality of life of women with CSD. The thickness of the remaining muscular layer (TRM) of CSD patients is considered to be the most important factor for determining subsequent pregnancy safety related to C-section scar ectopic pregnancy, uterine scar rupture and other complications [
23,
24].
The surgical curative effects of CSD are difficult to evaluate because there are many potential risk factors for CSD. These risk factors include the multiple cesarean sections, retroflexed uteri [
25], technique for repairing the uterine incision during cesarean section [
26] and other factors [
7]. Our study was the first to report the use of uterine contrast-enhanced Magnetic Resonance Imaging (MRI) for CSD evaluation [
27]. MRI is usually used for a preoperative work-up, and uterine contrast-enhanced MRI is a much better imaging method to measure the TRM, length, width and depth of the CSD than a general MRI scan. Although MRI assessment has been shown to be useful for patients with CSD, an optimal approach that combines multiple biomarkers as predictive factors has not been found yet.
Therefore, the aim of this study was to develop and validate an individualized score for preoperative prediction of outcomes in patients with CSD.