Impact of single- vs double-layer closure on adverse outcomes and uterine scar defect: a systematic review and metaanalysis

A systematic review and metaanalysis were performed through electronic database searches to estimate the effect of uterine closure at cesarean on the risk of adverse maternal outcome and on uterine scar evaluated by ultrasound. Randomized controlled trials, which compared single vs double layers and locking vs unlocking sutures for uterine closure of low transverse cesarean, were included. Outcomes were short-term complications (endometritis, wound infection, maternal infectious morbidity, blood transfusion, duration of surgical procedure, length of hospital stay, mean blood loss), uterine rupture or dehiscence at next pregnancy, and uterine scar evaluation by ultrasound. Twenty of 1278 citations were included in the analysis. We found that all types of closure were comparable for short-term maternal outcomes, except for single-layer closure, which had shorter operative time (-6.1 minutes; 95% confidence interval [CI], -8.7 to -3.4; P < .001) than double-layer closure. Single layer (-2.6 mm; 95% CI, -3.1 to -2.1; P < .001) and locked first layer (mean difference, -2.5 mm; 95% CI, -3.2 to -1.8; P < .001) were associated with lower residual myometrial thickness. Two studies reported no significant difference between single- vs double-layer closure for uterine dehiscence (relative risk, 1.86; 95% CI, 0.44-7.90; P = .40) or uterine rupture (no case). In conclusion, current evidence based on randomized trials does not support a specific type of uterine closure for optimal maternal outcomes and is insufficient to conclude about the risk of uterine rupture. Single-layer closure and locked first layer are possibly coupled with thinner residual myometrium thickness.