Review question
This review of trials assessed the effects of barrier agents on pelvic pain, live birth rate, clinical pregnancy rate, adhesion formation, and adhesion score (a measure of adhesion severity) after pelvic surgery.
Background
A common problem following pelvic surgery is the occurrence of adhesions, where the surfaces of two separate pelvic structures (e.g. inner lining of pelvic wall or pelvic organs such as uterus, ovaries, bladder, or bowel) stick together. During pelvic surgery, strategies to reduce pelvic adhesion formation include placing a synthetic physical barrier between pelvic structures.
Study characteristics
We included 19 randomised controlled trials (RCTs) that included a total of 1316 women undergoing gynaecological surgery. These trials assessed different types of barrier agents for preventing adhesions and compared them with each other or with no treatment. The data are current to August 2019. Thirteen RCTs reported commercial funding; the other studies did not state their source of funding.
Key results
No studies reported the effects of barrier agents used during pelvic surgery on pelvic pain or live birth rate among women of reproductive age.
Low-quality evidence suggests that oxidised regenerated cellulose and collagen membrane with polyethylene glycol plus glycerol may be more effective than no treatment in reducing the risk of adhesion formation following pelvic surgery.
One study reported the effect of collagen membrane with polyethylene glycol plus glycerol on postoperative adhesion score; however due to the way these data were reported, we are unable to interpret whether the intervention had any effect. No studies reported the effect of oxidised regenerated cellulose on adhesion score.
One study reported the effect of collagen membrane with polyethylene glycol plus glycerol on clinical pregnancy rate; however this evidence was found to be of very low quality. We are uncertain whether this intervention led to a higher clinical pregnancy rate than no treatment. No studies reported the effect of any other intervention on clinical pregnancy rate.
Two studies compared the effects of expanded polytetrafluoroethylene and oxidised regenerated cellulose on adhesion score and adhesion formation. However, this evidence was found to be of very low quality, and we are uncertain whether either intervention was more effective than the other. No studies compared the relative effects of these interventions on pelvic pain, live birth rate, or clinical pregnancy rate.
We found no conclusive evidence on the relative effectiveness of any reported interventions. No adverse events directly attributed to the adhesion agents were reported.
Quality of the evidence
The quality of the evidence ranged from very low to moderate. The most common limitations were imprecision (few participants and wide confidence intervals) and poor reporting of study methods. Most studies were commercially funded, and publication bias could not be ruled out.
We found no evidence on the effects of barrier agents used during pelvic surgery on pelvic pain or live birth rate in women of reproductive age because no trial reported these outcomes.
It is difficult to draw credible conclusions due to lack of evidence and the low quality of included studies. Given this caveat, low-quality evidence suggests that collagen membrane with polyethylene glycol plus glycerol may be more effective than no treatment in reducing the incidence of adhesion formation following pelvic surgery. Low-quality evidence also shows that oxidised regenerated cellulose may reduce the incidence of re-formation of adhesions when compared with no treatment at laparotomy. It is not possible to draw conclusions on the relative effectiveness of these interventions due to lack of evidence.
No adverse events directly attributed to the adhesion agents were reported. The quality of the evidence ranged from very low to moderate. Common limitations were imprecision and poor reporting of study methods. Most studies were commercially funded, and publication bias could not be ruled out.
Pelvic adhesions can form secondary to inflammation, endometriosis, or surgical trauma. Strategies to reduce pelvic adhesion formation include placing barrier agents such as oxidised regenerated cellulose, polytetrafluoroethylene, and fibrin or collagen sheets between pelvic structures.
To evaluate the effects of barrier agents used during pelvic surgery on rates of pain, live birth, and postoperative adhesions in women of reproductive age.
We searched the following databases in August 2019: the Cochrane Gynaecology and Fertility (CGF) Specialised Register of Controlled Trials, MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycINFO, the Cochrane Central Register of Controlled Trials (CENTRAL), Epistemonikos, and trial registries. We searched reference lists of relevant papers, conference proceedings, and grey literature sources. We contacted pharmaceutical companies for information and handsearched relevant journals and conference abstracts.
Randomised controlled trials (RCTs) on the use of barrier agents compared with other barrier agents, placebo, or no treatment for prevention of adhesions in women undergoing gynaecological surgery.
Three review authors independently assessed trials for eligibility and risk of bias and extracted data. We calculated odds ratios (ORs) or mean differences (MDs) with 95% confidence intervals (CIs) using a fixed-effect model. We assessed the overall quality of the evidence using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) methods.
We included 19 RCTs (1316 women). Seven RCTs randomised women; the remainder randomised pelvic organs. Laparoscopy (eight RCTs) and laparotomy (11 RCTs) were the primary surgical techniques. Indications for surgery included myomectomy (seven RCTs), ovarian surgery (five RCTs), pelvic adhesions (five RCTs), endometriosis (one RCT), and mixed gynaecological surgery (one RCT). The sole indication for surgery in three of the RCTs was infertility. Thirteen RCTs reported commercial funding; the rest did not state their source of funding.
No studies reported our primary outcomes of pelvic pain and live birth rate.
Oxidised regenerated cellulose versus no treatment at laparoscopy or laparotomy (13 RCTs)
At second-look laparoscopy, we are uncertain whether oxidised regenerated cellulose at laparoscopy reduced the incidence of de novo adhesions (OR 0.50, 95% CI 0.30 to 0.83, 3 RCTs, 360 participants; I² = 75%; very low-quality evidence) or of re-formed adhesions (OR 0.17, 95% CI 0.07 to 0.41, 3 RCTs, 100 participants; I² = 36%; very low-quality evidence).
At second-look laparoscopy, we are uncertain whether oxidised regenerated cellulose affected the incidence of de novo adhesions after laparotomy (OR 0.72, 95% CI 0.42 to 1.25, 1 RCT, 271 participants; very low-quality evidence). However, the incidence of re-formed adhesions may have been reduced in the intervention group (OR 0.38, 95% CI 0.27 to 0.55, 6 RCTs, 554 participants; I² = 41%; low-quality evidence).
No studies reported results on pelvic pain, live birth rate, adhesion score, or clinical pregnancy rate.
Expanded polytetrafluoroethylene versus oxidised regenerated cellulose at gynaecological surgery (two RCTs)
We are uncertain whether expanded polytetrafluoroethylene reduced the incidence of de novo adhesions at second-look laparoscopy (OR 0.93, 95% CI 0.26 to 3.41, 38 participants; very low-quality evidence). We are also uncertain whether expanded polytetrafluoroethylene resulted in a lower adhesion score (out of 11) (MD -3.79, 95% CI -5.12 to -2.46, 62 participants; very low-quality evidence) or a lower risk of re-formed adhesions (OR 0.13, 95% CI 0.02 to 0.80, 23 participants; very low-quality evidence) when compared with oxidised regenerated cellulose.
No studies reported results regarding pelvic pain, live birth rate, or clinical pregnancy rate.
Collagen membrane with polyethylene glycol and glycerol versus no treatment at gynaecological surgery (one RCT)
Evidence suggests that collagen membrane with polyethylene glycol and glycerol may reduce the incidence of adhesions at second-look laparoscopy (OR 0.04, 95% CI 0.00 to 0.77, 47 participants; low-quality evidence). We are uncertain whether collagen membrane with polyethylene glycol and glycerol improved clinical pregnancy rate (OR 5.69, 95% CI 1.38 to 23.48, 39 participants; very low-quality evidence).
One study reported adhesion scores but reported them as median scores rather than mean scores (median score 0.8 in the treatment group vs median score 1.2 in the control group) and therefore could not be included in the meta-analysis. The reported P value was 0.230, and no evidence suggests a difference between treatment and control groups.
No studies reported results regarding pelvic pain or live birth rate.
In total, 15 of the 19 RCTs included in this review reported adverse events. No events directly attributed to adhesion agents were reported.