Review question: This Cochrane systematic review evaluated all fluid and pharmacological agents that aim to prevent adhesion formation after gynaecological surgery (gels were defined as fluid agents).
Background: Adhesions are defined as internal scar tissue that may form as part of the body's healing process after surgery. They can also be caused by pelvic infection and endometriosis. Adhesions join together tissues and organs that are not normally connected. They are common after gynaecological surgery and can cause pelvic pain, infertility and bowel obstruction. Women with adhesions may need further surgery, which is more difficult and can lead to additional complications. The fluid agents are placed inside the pelvic cavity (which contains all female reproductive organs) during surgery and physically prevent raw, healing tissues from touching. These fluids can be broken down into hydroflotation agents or gels; hydroflotation agents are fluids placed in large volumes (usually around a litre); gels are directly applied to the internal surgical site. Pharmacological agents act by changing part of the healing process.
Study characteristics: 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.
Key results: 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).
Quality of the evidence: 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.