Abstract
KEY MESSAGE: Compared with conventional locked double-layer closure, an unlocked double-layer, endometrium-sparing closure was associated with lower isthmocele prevalence, greater residual myometrial thickness, and fewer postcesarean symptoms. If these findings are confirmed in prospective studies, adopting this closure approach could help to reduce morbidity related to the niche in routine cesarean practice. BACKGROUND: Isthmocele, a cesarean scar defect associated with abnormal bleeding, pelvic pain, and diminished fertility, is becoming more well known as a result of the increasing prevalence of cesarean sections. Although the optimal closure technique is still a topic of debate, it is regarded as the most modifiable factor in the prevention of isthmocele. OBJECTIVE: To compare the effects of the traditional locked double-layer uterine closure technique with the new unlocked double-layer, endometrium-protective technique on isthmocele incidence, residual myometrial thickness (RMT), and post-CS symptoms. METHODS: From March 2023 to January 2025, a total of 180 women (97 conventional and 83 novel) who underwent low-segment cesarean sections at a tertiary care center were included in a retrospective comparative cohort study. At 12-24 weeks postpartum, residual myometrial thickness (RMT) and isthmocele presence were evaluated using saline-infusion sonohysterography. Independent predictors of RMT and isthmocele were identified through binary logistic and multiple linear regression analyses. RESULTS: The new method was linked to less need for additional hemostatic sutures (2.4% vs. 11.3%; OR = 5.18), as well as a shorter operating time (26 vs. 33 min, p = 0.001). Compared with the new lockless double-layer technique, traditional locked double-layer closure was associated with a significantly higher risk of isthmocele (39.2% vs. 7.2%; OR = 8.27, 95%CI 3.28-20.85; p = 0.001). Additionally, the mean RMT was greater (13.91 vs. 10.18 mm, p = 0.001). While linear regression connected the novel technique and higher parity to greater RMT and preoperative anemia to decreased healing, logistic regression found that suture technique was the only independent predictor of isthmocele. The novel group had significantly lower rates of postmenstrual spotting, dysmenorrhea, and chronic pelvic pain (p = 0.001 for all). CONCLUSIONS: Compared to the traditional locking technique, the locking, double-layer, endometrium-sparing uterine closure method, in which the first layer of the uterine incision is continuously sutured without locking and the second layer is reinforced with a continuous 'U'-shaped suture, results in a statistically significant reduction in isthmocele formation, increased residual myometrial thickness, shorter operative time, and fewer niche-related symptoms. This method appears to improve short-term uterine healing and niche-related symptoms; however, its impact on future reproductive and obstetric outcomes remains unknown and requires prospective validation. However, multicenter studies with extended follow-up periods are warranted to confirm these findings.