Single-versus double-layer uterine closure at the time of cesarean delivery and risk of uterine scar niche: a systematic review and meta-analysis of randomized trials

Objective: This systematic review and meta-analysis compared single- versus double-layer uterine closure at the time of cesarean delivery. Data sources: MEDLINE, EMBASE, Scopus, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials were searched from inception until May 2024. Study eligibility criteria: We included only randomized controlled trials (RTSs) that compared single-layer versus double-layer uterine closure at the time of cesarean delivery. Study appraisal and synthesis methods: Outcomes were analyzed using a random-effects model. Results are expressed as risk differences. The assessment of the risk of bias was performed by using the Risk of Bias 2 tool. The primary outcome was the incidence of scar defects (i.e., niche) at 6 months after delivery. The secondary outcomes were incidence of scar defects at 6 weeks and 3 months. Results: A total of 18 studies were identified by the systematic review; 11 RCTs involving 6,058 participants were included in the meta-analysis. There is no statistical difference between single-layer and double-layer uterine closure of cesarean delivery incision regarding the incidence of uterine scar defect at six weeks. Single-layer closure showed a significantly lower incidence of niche after three months (RD = − 0.02 (− 0.06, 0.02); I2 = 81%, p < 0.01), and six months (RD = − 0.11, CI − 0.15, − 0.07, I2 = 91%, p < 0.01). Conclusions: Single-layer uterine closure at the time of cesarean delivery resulted in a lower uterine scar defects after three and six months compared to double-layer uterine closure. Systematic review registration: PROSPERO, Unique identifier: CRD42024552495.