Effect of single‐ versus double‐layer uterine closure during caesarean section on postmenstrual spotting (2Close): multicentre, double‐blind, randomised controlled superiority trial.

Objective: To evaluate whether double‐layer uterine closure after a first caesarean section (CS) is superior compared with single‐layer uterine closure in terms of postmenstrual spotting and niche development in the uterine caesarean scar. Design: Multicentre, double‐blind, randomised controlled superiority trial. Setting: Thirty‐two hospitals in the Netherlands. Population: A total of 2292 women aged ≥18 years undergoing a first CS were randomly assigned to each procedure (1:1): 1144 women were assigned to single‐layer uterine closure and 1148 women were assigned to double‐layer uterine closure. Methods: Single‐layer unlocked closure and double‐layer unlocked closure, with the second layer imbricating the first. Main outcome measures: Number of days with postmenstrual spotting during one menstrual cycle 9 months after CS. Secondary outcomes: perioperative and menstrual characteristics; transvaginal ultrasound measurements. Results: A total of 774 (67.7%) women from the single‐layer group and 770 (67.1%) women from the double‐layer group were evaluable for the primary outcome, as a result of drop‐out and amenorrhoea. The mean number of postmenstrual spotting days was 1.33 (bootstrapped 95% CI 1.12–1.54) after single‐layer closure and 1.26 (bootstrapped 95% CI 1.07–1.45) after double‐layer closure (adjusted mean difference −0.07, 95% CI −0.37 to 0.22, P = 0.810). The operative time was 3.9 minutes longer (95% CI 3.0–4.9 minutes, P < 0.001) and niche prevalence was 4.7% higher (95% CI 0.7–8.7%, P = 0.022) after double‐layer closure. Conclusions: The superiority of double‐layer closure compared with single‐layer closure in terms of postmenstrual spotting after a first CS was not shown. Long‐term obstetric follow‐up of our trial is needed to assess whether uterine caesarean closure guidelines should be adapted. Double‐layer uterine closure is not superior for postmenstrual spotting after a first caesarean; single‐layer closure performs slightly better on other outcomes. Double‐layer uterine closure is not superior for postmenstrual spotting after a first caesarean; single‐layer closure performs slightly better on other outcomes. [ABSTRACT FROM AUTHOR]