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

2Close study group

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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. Tweetable abstract: Double-layer uterine closure is not superior for postmenstrual spotting after a first caesarean; single-layer closure performs slightly better on other outcomes.

Original languageEnglish
Pages (from-to)866-878
Number of pages13
JournalBJOG: An International Journal of Obstetrics and Gynaecology
Issue number5
Early online date5 Sept 2020
Publication statusPublished - 1 Apr 2021


  • Caesarean section
  • double layer
  • niche
  • postmenstrual spotting
  • single layer
  • uterine closure technique

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