Abstract: Our search strategy identified 60 studies for consideration, of which 27 randomised trials involving 17,808 women undergoing caesarean section were included in the review. Overall, the methodological quality of the trials was variable, with 12 of the 27 included trials adequately describing the randomisation sequence, with less than half describing adequately methods of allocation concealment, and only six trials indicating blinding of outcome assessors. Two trials compared auto-suture devices with traditional hysterotomy involving 300 women. No statistically significant difference in febrile morbidity between the stapler and conventional incision groups was apparent (risk ratio (RR) 0.92; 95% confidence interval (CI) 0.38 to 2.20). Five studies were included in the review that compared blunt versus sharp dissection when performing the uterine incision involving 2141 women. There were no statistically significant differences identified for the primary outcome febrile morbidity following blunt or sharp extension of the uterine incision (four studies; 1941 women; RR 0.86; 95% CI 0.70 to 1.05). Mean blood loss (two studies; 1145 women; average mean difference (MD) -55.00 mL; 95% CI -79.48 to -30.52), and the need for blood transfusion (two studies; 1345 women; RR 0.24; 95% CI 0.09 to 0.62) were significantly lower following blunt extension. A single trial compared transverse with cephalad-caudad blunt extension of the uterine incision, involving 811 women, and while mean blood loss was reported to be lower following transverse extension (one study; 811 women; MD 42.00 mL; 95% CI 1.31 to 82.69), the clinical significance of such a small volume difference is of uncertain clinical relevance. There were no other statistically significant differences identified for the limited outcomes reported. A single trial comparing chromic catgut with polygactin-910, involving 9544 women reported that catgut closure versus closure with polygactin was associated with a significant reduction in the need for blood transfusion (one study, 9544 women, RR 0.49, 95% CI 0.32 to 0.76) and a significant reduction in complications requiring re-laparotomy (one study, 9544 women, RR 0.58, 95% CI 0.37 to 0.89). Nineteen studies were identified comparing single layer with double layer closure of the uterus, with data contributed to the meta-analyses from 14 studies. There were no statistically significant differences identified for the primary outcome, febrile morbidity (nine studies; 13,890 women; RR 0.98; 95% CI 0.85 to 1.12). Although the meta-analysis suggested single layer closure was associated with a reduction in mean blood loss, heterogeneity is high and this limits the clinical applicability of the result. There were no differences identified in risk of blood transfusion (four studies; 13,571 women; average RR 0.86; 95% CI 0.63 to 1.17; Heterogeneity: Tau² = 0.15; I² = 49%), or other reported clinical outcomes. Caesarean section is a common procedure performed on women worldwide. There is increasing evidence that for many techniques, short-term maternal outcomes are equivalent. Until long-term health effects are known, surgeons should continue to use the techniques they prefer and currently use.

Plain-language summary: The review authors searched the medical literature for randomised controlled trials to inform the most appropriate surgical techniques to use. Twenty-seven trials involving 17,808 women from a number of different countries contributed to the review. None of these trials assessed the type of uterine incision (side to side (transverse) lower uterine segment incision versus other types of uterine incision). Results from 18 randomised trials contributed to reports that single layer closure of the uterine incision was associated with a reduction in blood loss, and duration of the procedure. In these studies the surgical procedure for entering the abdominal cavity also differed and could have contributed to blood loss and duration of surgery. Five trials compared blunt with sharp dissection at the time of the uterine incision (2141 women) and a further two trials auto-suture devices with standard hysterotomy (300 women). Blunt surgery was associated with a reduction in mean blood loss at the time of the procedure. The use of an auto-suture instrument did not clearly reduce procedural blood loss but increased the duration of the procedure. Overall, trials focused on blood loss and duration of the operative procedure rather than clinical outcomes for the women. The methodological quality of the trials was variable.