Prognostic model on niche development after a first caesarean section:development and internal validation

Objective: To develop and internally validate a prognostic prediction model for development of a niche in the uterine scar after a first caesarean section (CS). Study design: Secondary analyses on data of a randomized controlled trial, performed in 32 hospitals in the Netherlands among women undergoing a first caesarean section. We used multivariable backward logistic regression. Missing data were handled using multiple imputation. Model performance was assessed by calibration and discrimination. Internal validation using bootstrapping techniques took place. The outcome was ‘development of a niche in the uterus’, defined as an indentation of = 2 mm in the myometrium. Results: We developed two models to predict niche development: in the total population and after elective CS. Patient related risk factors were: gestational age, twin pregnancy and smoking, and surgery related risk factors were double-layer closure and less surgical experience. Multiparity and Vicryl suture material were protective factors. The prediction model in women undergoing elective CS revealed similar results. After internal validation, Nagelkerke R2 ranged from 0.01 to 0.05 and was considered low; median area under the curve (AUC) ranged from 0.56 to 0.62, indicating failed to poor discriminative ability. Conclusions: The model cannot be used to accurately predict the development of a niche after a first CS. However, several factors seem to influence scar healing which indicates possibilities for future prevention such as surgical experience and suture material. The search for additional risk factors that play a role in development of a niche should be continued to improve the discriminative ability

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. 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