Abstract: Twenty-nine trials were included (3227 participants), and nine were excluded. One study examined pelvic pain and found no evidence of a difference between use of hydroflotation agents and no treatment. We found no evidence that any of the antiadhesion agents significantly affected the live birth rate. When gels were compared with no treatment or with hydroflotation agents at second-look laparoscopy (SLL), fewer participants who received a gel showed a worsening adhesion score when compared with those who received no treatment (OR 0.16, 95% CI 0.04 to 0.57, P value 0.005, two studies, 58 women, I2 = 0%, moderate-quality evidence) and with those given hydroflotation agents (OR 0.28, 95% CI 0.12 to 0.66, P value 0.003, two studies, 342 women, I2 = 0%, high-quality evidence). Participants who received steroids were less likely to have a worsening adhesion score (OR 0.27, 95% CI 0.12 to 0.58, P value 0.0008, two studies, 182 women, I2 = 0%, low-quality evidence). Participants were less likely to have adhesions at SLL if they received a hydroflotation agent or gel than if they received no treatment (OR 0.34, 95% CI 0.22 to 0.55, P value < 0.00001, four studies, 566 participants, I2 = 0%, high-quality evidence; OR 0.25, 95% CI 0.11 to 0.56, P value 0.0006, four studies, 134 women, I2 = 0%, high-quality evidence, respectively). When gels were compared with hydroflotation agents, participants who received a gel were less likely to have adhesions at SLL than those who received a hydroflotation agent (OR 0.36, 95% CI 0.19 to 0.67, P value 0.001, two studies, 342 women, I2 = 0%, high-quality evidence). No studies evaluated quality of life. In all studies apart from one, investigators stated that they were going to assess serious adverse outcomes associated with treatment agents, and no adverse effects were reported. Results suggest that for a woman with a 77% risk of developing adhesions without treatment, the risk of developing adhesions after use of a gel would be between 26% and 65%. For a woman with an 83% risk of worsening of adhesions after no treatment at initial surgery, the chance when a gel is used would be between 16% and 73%. Similarly, for hydroflotation fluids for a woman with an 84% chance of developing adhesions with no treatment, the risk of developing adhesions when hydroflotation fluid is used would be between 53% and 73%. Several of the included studies could not be included in a meta-analysis: The findings of these studies broadly agreed with the findings of the meta-analyses. The quality of the evidence, which was assessed using the GRADE approach, ranged from low to high. The main reasons for downgrading of evidence included imprecision (small sample sizes and wide confidence intervals) and poor reporting of study methods. Gels and hydroflotation agents appear to be effective adhesion prevention agents for use during gynaecological surgery, but no evidence indicates that they improve fertility outcomes or pelvic pain, and further research is required in this area. Future studies should measure outcomes in a uniform manner, using the modified American Fertility Society (mAFS) score. Statistical findings should be reported in full.

Plain-language summary: We included 29 randomised controlled trials in the review (3227 participants). Of these, results of 18 trials were pooled (2740 participants). Results from the remaining 11 trials could not be used in the meta-analysis because investigators did not use a way of measuring adhesions that would allow findings to be pooled with other data, or because important statistical information was not reported. We searched all evidence up to April 2014. Only one study evaluated pelvic pain and provided no evidence that the adhesion prevention agent made a difference. No evidence suggests that any of the investigated agents affected live birth rate. Regarding adhesions, participants given a fluid agent during surgery were less likely to form adhesions than participants who did not receive a fluid agent. When fluids and gels were compared with each other, gels appeared to perform better than fluids. No pharmacological agents showed good evidence of causing a significant effect on adhesions. No studies looked at differences in quality of life. All studies apart from one stated that investigators were going to assess serious adverse outcomes associated with the agents, and no adverse effects were reported. For gels, results suggest that for a woman with a 77% risk of developing adhesions without treatment, the risk of developing adhesions after a gel is used would be between 26% and 65%. For a woman with an 83% risk of worsening of adhesions after no treatment at initial surgery, the chance when a gel is used would be between 16% and 73%. Similarly, for hydroflotation fluids in a woman with an 84% chance of developing adhesions with no treatment, the risk of developing adhesions when hydroflotation fluid is used would be between 53% and 73%. Fluids and gels appear to be effective in reducing adhesions, but more information is needed to determine whether this affects pelvic pain, live birth rate, quality of life and long-term complications such as bowel obstruction. Further large, high-quality studies should be conducted in which investigators use the standard way of measuring adhesions as developed by the American Fertility Society (the modified AFS score). The quality of the evidence ranged from low to high. The main reasons for downgrading of evidence were imprecision (small sample sizes and wide confidence intervals) and poor reporting of study methods.