Efficacy of polyethylene glycol adhesion barrier after gynecological laparoscopic surgery: Results of a randomized controlled pilot study

Prevention of peritoneal adhesions after gynecological surgery: a systematic review

IMPORTANCE

The formation of adhesions after gynecological surgery not only has detrimental impacts on those affected, including pain, obstruction, and infertility, but also imposes a high economic burden on healthcare systems worldwide.

OBJECTIVE

The aim of this review was to evaluate the adhesion prevention potential of all currently available adhesion barriers for gynecological surgery.

EVIDENCE ACQUISITION

We systematically searched MEDLINE and CENTRAL databases for randomized controlled trials (RCTs) on the use of adhesion barriers as compared with peritoneal irrigation or no treatment in gynecological surgery. Only RCTs with second-look surgery to evaluate adhesions in the pelvic/abdominal (but not intrauterine) cavity were included.

RESULTS

We included 45 RCTs with a total of 4,120 patients examining a total of 10 unique types of barriers in second-look gynecological surgery. While RCTs on oxidized regenerated cellulose (significant improvement in 6 of 14 trials), polyethylene glycol with/without other agents (4/10), hyaluronic acid and hyaluronate + carboxymethylcellulose (7/10), icodextrin (1/3), dextran (0/3), fibrin-containing agents (1/2), expanded polytetrafluoroethylene (1/1), N,O-carboxymethylchitosan (0/1), and modified starch (1/1) overall showed inconsistent findings, results for expanded polytetrafluoroethylene, hyaluronic acid, and modified starch yielded the greatest improvements regarding adhesion reduction at 75%, 0-67%, and 85%, respectively.

CONCLUSIONS AND RELEVANCE

Best results for adhesion prevention were reported after applying Gore-Tex Surgical Membrane, hyaluronic acid, and 4DryField®. As Gore-Tex Surgical Membrane is nonabsorbable, it is associated with a greater risk of new adhesion formation due to second-look surgery to remove the product. 4DryField® yielded the greatest improvement in adhesion score compared to all other barrier agents (85%). For better comparability, future studies should use standardized scores and put more emphasis on patient-reported outcome measures, such as pain and infertility.

Barrier materials for prevention of surgical adhesions: systematic review

BACKGROUND

Postoperative surgical adhesions constitute a major health burden internationally. A wide range of materials have been evaluated, but despite constructive efforts and the obvious necessity, there remains no specific barrier widely utilized to prevent postoperative adhesion formation. The aim of this study was to highlight and characterize materials used for prevention of postoperative surgical adhesions in both animal and human studies.

METHODS

A systematic review was performed of all original research articles presenting data related to the prevention of postoperative adhesions using a barrier agent. All available observational studies and randomized trials using animal models or human participants were included, with no restrictions related to type of surgery. PubMed and Embase databases were searched using key terms from inception to August 2019. Standardized data collection forms were used to extract details for each study and assess desirable characteristics of each barrier and success in animal and/or human studies.

RESULTS

A total of 185 articles were identified for inclusion in the review, with a total of 67 unique adhesion barrier agents (37 natural and 30 synthetic materials). Desirable barrier characteristics of an ideal barrier were identified on review of the literature. Ten barriers achieved the primary outcome of reducing the incidence of postoperative adhesions in animal studies followed with positive outputs in human participants. A further 48 materials had successful results from animal studies, but with no human study performed to date.

DISCUSSION

Multiple barriers showed promise in animal studies, with several progressing to success, and fulfilment of desirable qualities, in human trials. No barrier is currently utilized commonly worldwide, but potential barriers have been identified to reduce the burden of postoperative adhesions and associated sequelae.

Impeding the Medical Protective Clothing Contamination by a Spray Coating of Trifunctional Polymers

The risk of fomite-mediated transmission in the clinic is substantially increasing amid the recent COVID-19 pandemic as personal protective equipment (PPE) of hospital workers is easily contaminated by direct contact with infected patients. In this context, it is crucial to devise a means to reduce such transmission. Herein, we report an antimicrobial, antiviral, and antibiofouling trifunctional polymer that can be easily coated onto the surface of medical protective clothing to effectively prevent pathogen contamination on the PPE. The coating layer is formed on the surfaces of PPE by the simple spray coating of an aqueous solution of the trifunctional polymer, poly(dodecyl methacrylate (DMA)-poly(ethylene glycol) methacrylate (PEGMA)-quaternary ammonium (QA)). To establish an optimal ratio of antifouling and antimicrobial functional groups, we performed antifouling, antibacterial, and antiviral tests using four different ratios of the polymers. Antifouling and bactericidal results were assessed using Staphylococcus aureus, a typical pathogenic bacterium that induces an upper respiratory infection. Regardless of the molar ratio, polymer-coated PPE surfaces showed considerable antiadhesion (∼65-75%) and antibacterial (∼75-87%) efficacies soon after being in contact with pathogens and maintained their capability for at least 24 h, which is sufficient for disposable PPEs. Further antiviral tests using coronaviruses showed favorable results with PPE coated at two specific ratios (3.5:6:0.5 and 3.5:5.5:1) of poly(DMA-PEGMA-QA). Moreover, biocompatibility assessments using the two most effective polymer ratios showed no recognizable local or systemic inflammatory responses in mice, suggesting the potential of this polymer for immediate use in the field.

Peritoneal Adhesions and their Prevention - Current Trends

The development of adhesions after gynecologic surgery is a severe problem with ramifications that go beyond the medical complications patients suffer (which most often include pain, obstruction and infertility), since they also impose a huge financial burden on the health care system and increase the workload of surgeons and all personnel involved in surgical follow-up care. Surgical techniques to avoid adhesion formation have not proven to be sufficient and pharmaceutical approaches for their prevention are even less effective, which means that the use of adhesion prevention devices is essential for achieving decent prophylaxis. This review explores the wide range of adhesion prevention products currently available on the market. Particular emphasis is put on prospective randomized controlled clinical trials that include second-look interventions, as these offer the most solid evidence of efficacy. We focused on adhesion scores, which are the most common way to quantify adhesion formation. This enables a direct comparison of the efficacies of different devices. While the greatest amount of data are available for oxidized regenerated cellulose, the outcomes with this adhesion barrier are mediocre and several studies have shown little efficacy. The best results have been achieved using adhesion barriers based on either modified starch, i.e., 4DryField® PH (PlantTec Medical GmbH, Lüneburg, Germany), or expanded polytetrafluoroethylene, i.e., GoreTex (W.L. Gore & Associates, Inc., Medical Products Division, Flagstaff, AZ), albeit the latter, as a non-resorbable barrier, has a huge disadvantage of having to be surgically removed again. Therefore, 4DryField® PH currently appears to be a promising approach and further studies are recommended.

Fluid and pharmacological agents for adhesion prevention after gynaecological surgery

BACKGROUND

Adhesions are fibrin bands that are a common consequence of gynaecological surgery. They are caused by conditions that include pelvic inflammatory disease and endometriosis. Adhesions are associated with comorbidities, including pelvic pain, subfertility, and small bowel obstruction. Adhesions also increase the likelihood of further surgery, causing distress and unnecessary expenses. Strategies to prevent adhesion formation include the use of fluid (also called hydroflotation) and gel agents, which aim to prevent healing tissues from touching one another, or drugs, aimed to change an aspect of the healing process, to make adhesions less likely to form.

OBJECTIVES

To evaluate the effectiveness and safety of fluid and pharmacological agents on rates of pain, live births, and adhesion prevention in women undergoing gynaecological surgery.

SEARCH METHODS

We searched: the Cochrane Gynaecology and Fertility Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, and Epistemonikos to 22 August 2019. We also checked the reference lists of relevant papers and contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials investigating the use of fluid (including gel) and pharmacological agents to prevent adhesions after gynaecological surgery.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. We assessed the overall quality of the evidence using GRADE methods. Outcomes of interest were pelvic pain; live birth rates; incidence of, mean, and changes in adhesion scores at second look-laparoscopy (SLL); clinical pregnancy, miscarriage, and ectopic pregnancy rates; quality of life at SLL; and adverse events.

MAIN RESULTS

We included 32 trials (3492 women), and excluded 11. We were unable to include data from nine studies in the statistical analyses, but the findings of these studies were broadly in keeping with the findings of the meta-analyses. Hydroflotation agents versus no hydroflotation agents (10 RCTs) We are uncertain whether hydroflotation agents affected pelvic pain (odds ratio (OR) 1.05, 95% confidence interval (CI) 0.52 to 2.09; one study, 226 women; very low-quality evidence). It is unclear whether hydroflotation agents affected live birth rates (OR 0.67, 95% CI 0.29 to 1.58; two studies, 208 women; low-quality evidence) compared with no treatment. Hydroflotation agents reduced the incidence of adhesions at SLL when compared with no treatment (OR 0.34, 95% CI 0.22 to 0.55, four studies, 566 women; high-quality evidence). The evidence suggests that in women with an 84% chance of having adhesions at SLL with no treatment, using hydroflotation agents would result in 54% to 75% having adhesions. Hydroflotation agents probably made little or no difference to mean adhesion score at SLL (standardised mean difference (SMD) -0.06, 95% CI -0.20 to 0.09; four studies, 722 women; moderate-quality evidence). It is unclear whether hydroflotation agents affected clinical pregnancy rate (OR 0.64, 95% CI 0.36 to 1.14; three studies, 310 women; moderate-quality evidence) compared with no treatment. This suggests that in women with a 26% chance of clinical pregnancy with no treatment, using hydroflotation agents would result in a clinical pregnancy rate of 11% to 28%. No studies reported any adverse events attributable to the intervention. Gel agents versus no treatment (12 RCTs) No studies in this comparison reported pelvic pain or live birth rate. Gel agents reduced the incidence of adhesions at SLL compared with no treatment (OR 0.26, 95% CI 0.12 to 0.57; five studies, 147 women; high-quality evidence). This suggests that in women with an 84% chance of having adhesions at SLL with no treatment, the use of gel agents would result in 39% to 75% having adhesions. It is unclear whether gel agents affected mean adhesion scores at SLL (SMD -0.50, 95% CI -1.09 to 0.09; four studies, 159 women; moderate-quality evidence), or clinical pregnancy rate (OR 0.20, 95% CI 0.02 to 2.02; one study, 30 women; low-quality evidence). No studies in this comparison reported on adverse events attributable to the intervention. Gel agents versus hydroflotation agents when used as an instillant (3 RCTs) No studies in this comparison reported pelvic pain, live birth rate or clinical pregnancy rate. Gel agents probably reduce the incidence of adhesions at SLL when compared with hydroflotation agents (OR 0.50, 95% CI 0.31 to 0.83; three studies, 538 women; moderate-quality evidence). This suggests that in women with a 46% chance of having adhesions at SLL with a hydroflotation agent, the use of gel agents would result in 21% to 41% having adhesions. We are uncertain whether gel agents improved mean adhesion scores at SLL when compared with hydroflotation agents (MD -0.79, 95% CI -0.82 to -0.76; one study, 77 women; very low-quality evidence). No studies in this comparison reported on adverse events attributable to the intervention. Steroids (any route) versus no steroids (4 RCTs) No studies in this comparison reported pelvic pain, incidence of adhesions at SLL or mean adhesion score at SLL. It is unclear whether steroids affected live birth rates compared with no steroids (OR 0.65, 95% CI 0.26 to 1.62; two studies, 223 women; low-quality evidence), or clinical pregnancy rates (OR 1.01, 95% CI 0.66 to 1.55; three studies, 410 women; low-quality evidence). No studies in this comparison reported on adverse events attributable to the intervention.

AUTHORS' CONCLUSIONS

Gels and hydroflotation agents appear to be effective adhesion prevention agents for use during gynaecological surgery, but we found no evidence indicating that they improve fertility outcomes or pelvic pain, and further research is required in this area. It is also worth noting that for some comparisons, wide confidence intervals crossing the line of no effect meant that clinical harm as a result of interventions could not be excluded. Future studies should measure outcomes in a uniform manner, using the modified American Fertility Society score. Statistical findings should be reported in full. No studies reported any adverse events attributable to intervention.

Polypropylene meshes coated with chitosan/polyethylene glycol for the reconstruction of the abdominal wall: an experimental study in rats

ABSTRACT The aim of this study was to characterize the tissue reactions triggered by the polypropylene mesh coated with chitosan and polyethylene glycol film, and if it’s able to prevent the formation of peritoneal adhesions. Defects in the abdominal wall of rats were induced and polypropylene meshes coated with chitosan/polyethylene glycol (CPEG group, n= 12) and uncoated (PP control group, n= 12) were implanted. On the fourth and forty-fifth postoperative day the formation of adhesion and the tissue reaction to the biomaterial was evaluated through histological and histochemical analysis. The area (P= 0.01) and severity (P= 0.002) of the adhesion was significatively less in the CPEG group. On the fourth day the foreign body reaction was less intense in CPEG group (P= 0.018) and the production of collagen fibers was more intense in this group (P= 0.041). The tissue reactions caused by the biomaterials were similar on the 45th day, with the exception of the high organization of collagen fibers in the CPEG group. The CPEG meshes did not fully prevent the formation of adhesions, but minimized the severity of the process. The foreign body reaction promoted by polypropylene meshes coated with CPEG is less intense than that triggered by uncoated polypropylene meshes.

A new bioabsorbable polymer film to prevent peritoneal adhesions validated in a post-surgical animal model

Background

Peritoneal adhesions are a serious surgical postoperative complication. The aim of this study is to investigate, in a rat model, the anti-adhesive effects of a bioabsorbable film of polymer combining polyethylene glycol and polylactic acid.

Materials and methods

Sixty-three animals were randomized into five groups according to the anti-adhesion treatment: Hyalobarrier^®, Seprafilm^®, Polymer A (PA), Polymer B (PB), and control. The rats were euthanized on days 5 and 12 to evaluate the extent, severity and degree of adhesions and histopathological changes. Three animals were euthanized at day 2 in PA, PB and control groups to observe the in vivo elimination.

Results

Macroscopic adhesion formation was significantly lower in the PA group than in the control group at day 5 (median adhesion score 0±0 vs 9.6 ±0.5 p = 0.002) and at day 12 (0±0 vs 7.3±4 p = 0.02). Furthermore, median adhesion score at day 5 was significantly lower in the PA group than in the Seprafilm group (0±0 vs 4.2± 3.9 p = 0.03). Residence time of PA seems longer than PB.

Conclusion

The PA bioabsorbable film seems efficient in preventing the formation of peritoneal adhesions.

Absorptive anti-adhesion barrier for the prevention of bowel obstruction after laparoscopic colorectal cancer surgery

Objectives: The protective efficacy of an absorptive adhesion prevention product (Seprafilm^Ⓡ) against bowel obstruction (BO) during open surgery was demonstrated in a large-scale randomized controlled clinical trial in Europe and America. However, the efficacy of Seprafilm against BO in laparoscopic surgery remains uncertain. The objective of this study was to clarify the protective efficacy of Seprafilm against BO after laparoscopic surgery for colorectal cancer. Methods: From 2009 to 2016, 1328 laparoscopic colorectal resections were performed for colorectal cancer. From 2009, Seprafilm was used for preventing BO in laparoscopic colorectal surgery. The incidence of BO and short-term results were compared between the Seprafilm and non-Seprafilm groups after propensity score matching. Results: Propensity scoring generated 270 matched patients per group for the comparisons between the Seprafilm and non-Seprafilm groups. The two groups showed no significant differences regarding patients' backgrounds. Among all patients, 73.1% (19/26) of BO occurred within 30 days after the surgery. Significantly lower incidences of all grade (2.6% vs. 7.0%; p = 0.016) and grade 2 + 3a (1.5% vs. 5.2%; p = 0.017) BO were observed in the Seprafilm group than in the non-Seprafilm group; no significant difference regarding grade 3b BO (1.1% vs. 1.9%; p = 0.476) was found. A significant difference in BO within 30 days was also noted between the two groups (1.9% vs. 5.2%, p = 0.036). There were no significant differences between the groups regarding anastomotic leakage and deep surgical site infection. Conclusions: Seprafilm was useful for preventing BO, requiring decompression therapy of the bowel, after laparoscopic colorectal surgery without increasing adverse events.

Adhesion prevention agents for gynaecological surgery: an overview of Cochrane reviews

BACKGROUND

Intraperitoneal adhesions are associated with considerable co-morbidity and have large financial and public health repercussions. They have secondary effects that include chronic pelvic pain, dyspareunia, subfertility and bowel obstruction. In women with adhesions, subsequent surgery is more difficult, often takes longer, and is associated with a higher complication rate (Broek 2013). The significant burden of adhesions has led to the development of several anti-adhesion agents, although there is disagreement as to their relative effectiveness.

OBJECTIVES

To summarise evidence derived from Cochrane systematic reviews on the clinical safety and effectiveness of solid agents, gel agents, liquid agents and pharmacological agents, used as adjuvants to prevent formation of adhesions after gynaecological pelvic surgery.

METHODS

The Cochrane Database of Systematic Reviews was searched using the keyword 'adhesion' up to August 2014. The Cochrane information management system was also searched for any titles or protocols of reviews in progress. Two review authors independently extracted information from the reviews, with disagreements being resolved by a third review author. The quality of the included reviews was described in a narrative manner, and the AMSTAR tool was used to formally assess each review included in this overview. The quality of evidence provided in the original reviews was described using GRADE methods.

MAIN RESULTS

We included two reviews, one with 18 studies comparing solid agents (oxidised regenerated cellulose expanded polytetrafluoroethylene, sodium hyaluronate and carboxymethylcellulose, and fibrin sheets) with control or with each other. The other review included 29 studies which compared liquid agents (4% icodextrin, 32% dextran, crystalloids), gel agents (carboxymethylcellulose and polyethylene oxide, polyethylene glycol gels, hyaluronic acid based gel, 0.5% ferric hyaluronate gel, sodium hyaluronate spray) and pharmacological agents (gonadotrophin-releasing hormone agonist, reteplase plasminogen activator, N,O-carboxymethyl chitosan, steroid agents, intraperitoneal noxytioline, intraperitoneal heparin, systemic promethazine) with control or each other. Both reviews met all of the criteria of the AMSTAR assessment.The reviews included as outcomes both the primary outcomes of this overview (pelvic pain, pregnancy, live birth rate and quality of life (QoL)) and our secondary outcomes (adverse effects, presence or absence of adhesions at second-look laparoscopy (SLL) and adhesion score). However, neither of the reviews identified any primary studies of solid, gel or pharmacological agents that reported any of our primary outcomes. The only studies in either review that reported any of our primary outcomes were studies comparing liquid agents versus control (saline or Hartmann's solution), which reported pelvic pain (two studies), live birth (two studies) and pregnancy (three studies).An external source of funding was stated for 25 of the 47 studies across both reviews; in 24 of these studies the funding was commercial. Solid agents (18 studies)None of our primary outcomes were reported. Adverse events were reported as an outcome by only 9 of the 18 studies. These reported no adverse events. Liquid agents (nine studies)There was no evidence of a difference between liquid agents and control (saline or Hartmann's solution) with respect to pelvic pain (odds ratio (OR) 0.65, 95% confidence interval (CI) 0.37 to 1.14, 1 study, n = 286, moderate quality evidence), pregnancy rate (OR 0.64, 95% CI 0.36 to 1.14, 3 studies, n = 310, moderate quality evidence) or live birth rate (OR 0.67, 95% CI 0.29 to 1.58, 2 studies, n = 208, moderate quality evidence). No studies of liquid agents reported QoL. Adverse events were not reported as an outcome by any of the nine studies. Gel agents (seven studies)None of our primary outcomes were reported. Adverse events were not reported as an outcome by any of the seven studies. Pharmacological agents (seven studies)None of our primary outcomes were reported. Adverse events were reported as an outcome by only one of the seven primary studies. This study reported no evidence of difference in ectopic pregnancy rates between intraperitoneal noxytioline and no treatment (OR 4.91, 95% CI 0.45 to 53.27, 1 study, n = 33, low quality evidence).

AUTHORS' CONCLUSIONS

There is insufficient evidence to allow us to draw any conclusions about the effectiveness and safety of anti-adhesion agents in gynaecological surgery, due to the lack of data on pelvic pain, fertility outcomes, quality of life or safety. A substantial proportion of research in this field has been funded by private companies that manufacture these agents, and further high powered, independent trials will be needed before definitive conclusions can be made.

Safety and efficacy of postoperative continuous intra-peritoneal wash with lactated Ringer's for minimizing post-myomectomy pelvic adhesions: a pilot clinical trial

OBJECTIVES

To assess efficacy and safety of post-operative intra-peritoneal wash with lactated Ringer's for 48h after myomectomy in reduction of adhesions compared to routine intra-operative irrigation. Study design A prospective, randomized trial that included 52 eligible participants who had undergone abdominal myomectomy. Participants were randomly allocated to a treatment group (n=26) which was subjected to continuous peritoneal wash for 48h via two intraperitoneal drains, and a control group (n=26). The incidence of de novo adhesions and their severity and extent were scored at a second-look laparoscopy 8-10 weeks postoperatively. Adhesions were graded using the local adhesion barrier scoring system score. Adverse effects were also assessed and reported.

RESULTS

There was no statistically significant difference in duration of hospital stay or in the incidence of adverse events. A significantly higher proportion of adhesion-free patients was found in the treatment group [11/23, 47.8%] compared to the control group [4/21, 19%] (P<0.01). The mean number of pelvic sites covered by adhesions was significantly lower in the treatment group than in the control group (2.2±0.3 versus 4.6±0.8, P<0.05). The total adhesion score was significantly lower in the treatment group than in the control group (2.1±0.5 versus 4.8±1.4, P<0.05) and the adhesion score was significantly lower at most of the individual anatomical sites.

CONCLUSIONS

Application of postoperative intraperitoneal wash with lactated Ringer's solution for 48h may have reasonable safety and efficacy in minimizing postoperative pelvic de novo adhesions following abdominal myomectomy.

Fluid and pharmacological agents for adhesion prevention after gynaecological surgery

BACKGROUND

Adhesions are fibrin bands that are a common consequence of gynaecological surgery. They are caused by various conditions including pelvic inflammatory disease and endometriosis. Adhesions are associated with considerable co-morbidity, including pelvic pain, subfertility and small bowel obstruction. Patients may require further surgery-a fact that has financial implications.

OBJECTIVES

To evaluate the role of fluid and pharmacological agents used as adjuvants in preventing formation of adhesions after gynaecological surgery.

SEARCH METHODS

The following databases were searched up to April 2014: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and PsycINFO. Studies involving hydroflotation, gel and such pharmacological agents as steroids, noxytioline, heparin, promethazine, N,O-carboxymethyl chitosan and gonadotrophin-releasing hormone agonists were evaluated.

SELECTION CRITERIA

Randomised controlled trials investigating the use of fluid and pharmacological agents to prevent adhesions after gynaecological surgery. Gels were defined as fluid agents.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed trials for eligibility, extracted data and evaluated risk of bias. Results were expressed as odds ratios (ORs), mean differences (MDs) or standard mean differences (SMDs) as appropriate, with 95% confidence intervals (CIs).

MAIN RESULTS

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, I(2) = 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, I(2) = 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, I(2) = 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, I(2) = 0%, high-quality evidence; OR 0.25, 95% CI 0.11 to 0.56, P value 0.0006, four studies, 134 women, I(2) = 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, I(2) = 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.

AUTHORS' CONCLUSIONS

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.

Peritoneal adhesions after laparoscopic gastrointestinal surgery

Although laparoscopy has the potential to reduce peritoneal trauma and post-operative peritoneal adhesion formation, only one randomized controlled trial and a few comparative retrospective clinical studies have addressed this issue. Laparoscopy reduces de novo adhesion formation but has no efficacy in reducing adhesion reformation after adhesiolysis. Moreover, several studies have suggested that the reduction of de novo post-operative adhesions does not seem to have a significant clinical impact. Experimental data in animal models have suggested that CO₂ pneumoperitoneum can cause acute peritoneal inflammation during laparoscopy depending on the insufflation pressure and the surgery duration. Broad peritoneal cavity protection by the insufflation of a low-temperature humidified gas mixture of CO₂, N₂O and O₂ seems to represent the best approach for reducing peritoneal inflammation due to pneumoperitoneum. However, these experimental data have not had a significant impact on the modification of laparoscopic instrumentation. In contrast, surgeons should train themselves to perform laparoscopy quickly, and they should complete their learning curves before testing chemical anti-adhesive agents and anti-adhesion barriers. Chemical anti-adhesive agents have the potential to exert broad peritoneal cavity protection against adhesion formation, but when these agents are used alone, the concentrations needed to prevent adhesions are too high and could cause major post-operative side effects. Anti-adhesion barriers have been used mainly in open surgery, but some clinical data from laparoscopic surgeries are already available. Sprays, gels, and fluid barriers are easier to apply in laparoscopic surgery than solid barriers. Results have been encouraging with solid barriers, spray barriers, and gel barriers, but they have been ambiguous with fluid barriers. Moreover, when barriers have been used alone, the maximum protection against adhesion formation has been no greater than 60%. A recent small, randomized clinical trial suggested that the combination of broad peritoneal cavity protection with local application of a barrier could be almost 100% effective in preventing post-operative adhesion formation. Future studies should confirm the efficacy of this global strategy in preventing adhesion formation after laparoscopy by focusing on clinical end points, such as reduced incidences of bowel obstruction and abdominal pain and increased fertility.

Benefits and harms of adhesion barriers for abdominal surgery: a systematic review and meta-analysis

BACKGROUND

Formation of adhesions after peritoneal surgery results in high morbidity. Barriers to prevent adhesion are seldom applied, despite their ability to reduce the severity of adhesion formation. We evaluated the benefits and harms of four adhesion barriers that have been approved for clinical use.

METHODS

In this systematic review and meta-analysis, we searched PubMed, CENTRAL, and Embase for randomised clinical trials assessing use of oxidised regenerated cellulose, hyaluronate carboxymethylcellulose, icodextrin, or polyethylene glycol in abdominal surgery. Two researchers independently identified reports and extracted data. We compared use of a barrier with no barrier for nine predefined outcomes, graded for clinical relevance. The primary outcome was reoperation for adhesive small bowel obstruction. We assessed systematic error, random error, and design error with the error matrix approach. This study is registered with PROSPERO, number CRD42012003321.

FINDINGS

Our search returned 1840 results, from which 28 trials (5191 patients) were included in our meta-analysis. The risks of systematic and random errors were low. No trials reported data for the effect of oxidised regenerated cellulose or polyethylene glycol on reoperations for adhesive small bowel obstruction. Oxidised regenerated cellulose reduced the incidence of adhesions (relative risk [RR] 0·51, 95% CI 0·31-0·86). Some evidence suggests that hyaluronate carboxymethylcellulose reduces the incidence of reoperations for adhesive small bowel obstruction (RR 0·49, 95% CI 0·28-0·88). For icodextrin, reoperation for adhesive small bowel obstruction did not differ significantly between groups (RR 0·33, 95% CI 0·03-3·11). No barriers were associated with an increase in serious adverse events.

INTERPRETATION

Oxidised regenerated cellulose and hyaluronate carboxymethylcellulose can safely reduce clinically relevant consequences of adhesions.

FUNDING

None.