Effect of single- and double-layer cesarean section closure on residual myometrial thickness and isthmocele - a systematic review and meta-analysis

Objective: To determine the incidence of isthmocele, its effect on residual myometrial thickness (RMT), and other complications of Cesarean delivery (CD) in relation to single- and double-layer CD closure. We searched PubMed, SCOPUS, Web of Science, ClinicalTrials.gov, MEDLINE and Cochrane Library for relevant clinical trials assessing the use of single- and double-layer uterine closure in patients undergoing cesarean sections from inception through to March 2021. Materials and Methods: Our population was women undergoing cesarean section with uterine closure by any double-layer method, compared with those undergoing uterine closure through a single-layer method. RMT (in mm) was measured at 6 weeks, niche/isthmocele existence at 6 weeks, RMT (in mm) at 6-24 months and niche/isthmocele existence at 6-24 months. In order to present the highest quality evidence, we only included clinical trials in our analysis. To perform this review, we reported dichotomous outcomes using percent and total, while continuous outcomes were reported using mean ± standard deviations, and relative 95% confidence intervals using the inverse variance method. Results: We found that the RMT in the double-layer closure group was significantly higher at six weeks [mean difference (MD)=-0.43 (-0.77, -0.09)], (p=0.01) and at 6-24 months of follow-up [MD=-1.27 (-2.28, -0.25)], (p=0.01). The incidence of isthmocele in the two groups, as well as the other investigated outcomes were similar across the different groups. Conclusion: High-quality evidence shows that double-layer closure results in a higher RMT compared with a single-layer closure, despite no significant difference in isthmocele formation.