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); I 2 = 81%, p < 0.01), and six months (RD = − 0.11, CI − 0.15, − 0.07, I 2 = 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.