Abstract: Five trials involving 836 participants randomised to peritoneal closure (410 participants) and no peritoneal closure (426 participants) were included in this review. All the trials were at high risk of bias. All the trials included participants undergoing laparotomy (open surgery). Four of the five trials used catgut or chromic catgut for peritoneal closure. Three trials involved vertical incisions and two trials involved transverse incisions. None of the trials reported 30-day mortality. There was no significant difference in the one-year mortality between the two groups (RR 1.11; 95% CI 0.56 to 2.19) in the only trial that reported this outcome. The only serious peri-operative adverse event reported was burst abdomen, which was reported by three trials. Overall, 10/663 (1.5%) of participants developed burst abdomen. There was no significant difference in the proportion of participants who developed burst abdomen between the two groups (RR 0.71; 95% CI 0.22 to 2.35). The same three trials reported the proportion of participants who developed incisional hernia. Details of the follow-up period were only available for one trial, and so we were unable to calculate the incidence rate. Overall, 17/663 (2.5%) of participants developed incisional hernia. There was no significant difference in the proportion of participants who developed incisional hernia between the two groups (RR 0.92; 95% CI 0.37 to 2.28). None of the trials reported quality of life; the incidence rate of, or proportion of participants who developed, intestinal obstruction due to adhesions; or re-operation due to incisional hernia or adhesions. Only one trial reported the length of hospital stay, and this trial did not include readmissions in its calculations. There was no significant difference in the length of hospital stay between the two groups (MD 0.40 days; 95% CI -0.51 to 1.31). There is no evidence for any short-term or long-term advantage in peritoneal closure for non-obstetric operations. If further trials are performed on this topic, they should have an adequate period of follow-up and adequate measures should be taken to ensure that the results are not subject to bias.

Plain-language summary: We identified five trials involving 836 participants who had open abdominal operations. Peritoneal closure was done in 410 participants and not done in 426. All trials had a high risk of bias. Only one trial reported the proportion of participants who died up to one year after the operation, and there was no significant difference between the closure and non-closure groups. Three trials reported major wound breakdown (burst abdomen), which requires emergency surgery. Overall, 10/663 participants (1.5%) developed burst abdomen, with no significant difference in proportions between the two groups. Three trials reported minor wound breakdown (incisional hernia), that may require surgery. Overall, 17/663 participants (2.5%) developed incisional hernia; again there was no significant difference between the two groups. None of the trials reported on important outcomes, such as quality of life; the occurrence of intestinal obstruction (caused by intestines sticking to themselves and the abdominal wall (adhesions)); or the proportion of participants who had surgery to fix incisional hernia or adhesions. Only one trial reported length of hospital stay, and showed no significant difference between the groups, but did not include readmissions in its calculations. There does not appear to be any evidence for a short-term or long-term advantage in peritoneal closure in operations not related to childbirth. However, the trials were at high risk of bias, which can lead to false conclusions. Interestingly, our findings are similar to those of another research group who performed a similar review for operations related to childbirth.