Expanded polytetrafluoroethylene (Gore-Tex Surgical Membrane*) is superior to oxidized regenerated cellulose (Interceed TC7 †) in preventing adhesions‡§*W. L. Gore & Associates, Inc., Flagstaff, Arizona.†Johnson & Johnson Medical, Inc., Arlington, Texas.‡Sponsored by a grant from W. L. Gore & Associates, Inc., Flagstaff, Arizona.§Presented at the 50th Annual Meeting of The American Fertility Society, San Antonio, Texas, November 8 to 11, 1994

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.

Update on antiadhesion barriers and therapeutics in gynecological surgery

PURPOSE OF REVIEW

Postoperative adhesions remain a clinical challenge to both patients and providers, as they are associated with significant complications and a high economic burden. This article provides a clinical review of currently available antiadhesive agents and promising new therapies that have advanced past animal studies.

RECENT FINDINGS

Several agents have been investigated on their ability to reduce adhesion formation; however, there is no widely acceptable option. The few available interventions are barrier agents and while low-quality evidence suggests that they may be more effective than no treatment, there is no general agreement on their overall efficacy. There is an abundance of research on new solutions; however, their clinical efficacy is yet to be determined.

SUMMARY

Although a wide range of therapeutics have been investigated, majority are halted in animal models with only a select few being studied in humans and ultimately available in the market. Many agents have shown effectiveness in reducing adhesion formation, however, that has not been translated to improvement in clinically relevant outcomes; hence the need for high-quality large randomized trials.

Engineering a cell-hydrogel-fibre composite to mimic the structure and function of the tendon synovial sheath

The repair of tendon injuries is often compromised by post-operative peritendinous adhesions. Placing a physical barrier at the interface between the tendon and the surrounding tissue could potentially solve this problem by reducing adhesion formation. At present, no such system is available for routine use in clinical practice. Here, we propose the development of a bilayer membrane combining a nanofibrous poly(ε-caprolactone) (PCL) electrospun mesh with a layer of self-assembling peptide hydrogel (SAPH) laden with type-B synoviocytes. This bilayer membrane would act as an anti-adhesion system capable of restoring tendon lubrication, while assisting with synovial sheath regeneration. The PCL mesh showed adequate mechanical properties (Young's modulus=19±4 MPa, ultimate tensile stress=9.6±1.7 MPa, failure load=0.5±0.1 N), indicating that the membrane is easy to handle and capable to withstand the frictional forces generated on the tendon's surface during movement (~0.3 N). Morphological analysis confirmed the generation of a mesh with nanosized PCL fibres and small pores (< 3 μm), which prevented fibroblast infiltration to impede extrinsic healing but still allowing diffusion of nutrients and waste. Rheological tests showed that incorporation of SAPH layer allows good lubrication properties when the membrane is articulated against porcine tendon or hypodermis, suggesting that restoration of tendon gliding is possible upon implantation. Moreover, viability and metabolic activity tests indicated that the SAPH was conducive to rabbit synoviocyte growth and proliferation over 28 days of 3D culture, sustaining cell production of specific matrix components, particularly hyaluronic acid. Synoviocyte-laden peptide hydrogel promoted a sustained endogenous production of hyaluronic acid, providing an anti-friction layer that potentially restores the tendon gliding environment.

Berberine prevents primary peritoneal adhesion and adhesion reformation by directly inhibiting TIMP-1

Peritoneal adhesions are fibrous tissues that tether organs to one another or to the peritoneal wall and represent the major cause of postsurgical morbidity. Enterolysis at repeat surgeries induces adhesion reformation that is more difficult to prevent than primary adhesion. Here we studied the preventive effects of different approaches of berberine treatment for primary adhesion, and its effects on adhesion reformation compared to Interceed. We found the primary adhesion was remarkably prevented by berberine through intraperitoneal injection 30 min before abrasive surgery (pre-berberine) or direct addition into injured cecum immediately after the surgery (inter-berberine). Rats with adhesion reformation had a more deteriorative collagen accumulation and tissue injury in abrasive sites than rats with primary adhesion. The dysregulated TIMP-1/MMP balance was observed in patients after surgery, as well as adhesion tissues from primary adhesion or adhesion reformation rats. Inter-berberine treatment had a better effect for adhesion reformation prevention than Interceed. Berberine promoted the activation of MMP-3 and MMP-8 by directly blocking TIMP-1 activation core, which was reversed by TIMP-1 overexpression in fibroblasts. In conclusion, this study suggests berberine as a reasonable approach for preventing primary adhesion formation and adhesion reformation.

Barrier agents for adhesion prevention after gynaecological surgery

BACKGROUND

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.

OBJECTIVES

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.

SEARCH METHODS

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.

SELECTION CRITERIA

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.

DATA COLLECTION AND ANALYSIS

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.

MAIN RESULTS

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.

AUTHORS' CONCLUSIONS

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.

Active agents, biomaterials, and technologies to improve biolubrication and strengthen soft tissues

Normal functioning of articulating tissues is required for many physiological processes occurring across length scales from the molecular to whole organism. Lubricating biopolymers are present natively on tissue surfaces at various sites of biological articulation, including eyelid, mouth, and synovial joints. The range of operating conditions at these disparate interfaces yields a variety of tribological mechanisms through which compressive and shear forces are dissipated to protect tissues from material wear and fatigue. This review focuses on recent advances in active agents and biomaterials for therapeutic augmentation of friction, lubrication, and wear in disease and injured states. Various small-molecule, biological, and gene delivery therapies are described, as are tribosupplementation with naturally-occurring and synthetic biolubricants and polymer reinforcements. While reintroduction of a diseased tissue's native lubricant received significant attention in the past, recent discoveries and pre-clinical research are capitalizing on concurrent advances in the molecular sciences and bioengineering fields, with an understanding of the underlying tissue structure and physiology, to afford a desired, and potentially patient-specific, tissue mechanical response for restoration of normal function. Small and large molecule drugs targeting recently elucidated pathways as well as synthetic and hybrid natural/synthetic biomaterials for restoring a desired tissue mechanical response are being investigated for treatment of, for example, keratoconjunctivitis sicca, xeroderma, and osteoarthritis.

A Novel Non-Planar Transverse Stretching Process for Micro-Porous PTFE Membranes and Resulting Characteristics

Polytetrafluoroethylene (PTFE) micro-porous membranes were prepared from PTFE fine powder through extruding, rolling, and uniaxial longitudinally stretching. In contrast to conventional planar transverse stretching, a novel 3D mold design of non-planar transverse stretching process was employed in this study to produce micro-porous structure. The morphology, membrane thickness, mean pore size, and porosity of the PTFE membrane were investigated. The results show that the non-planar transverse stretched membranes exhibit more uniform average pore diameter with thinner membrane thickness. Morphological changes induced by planar and non-planar transverse stretching for pore characteristics were investigated. The stretching conditions, stretching temperature and rate, affect the stretched membrane. Increasing temperature facilitated the uniformity of pore size and uniformity of membrane thickness. Moreover, increase in stretching rate resulted in finer pore size and thinner membrane.

Barrier agents for adhesion prevention after gynaecological surgery

BACKGROUND

Pelvic adhesions can form as a result of inflammation, endometriosis or surgical trauma. During pelvic surgery, strategies to reduce pelvic adhesion formation include placing barrier agents such as oxidised regenerated cellulose, polytetrafluoroethylene or fibrin sheets between the pelvic structures.

OBJECTIVES

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.

SEARCH METHODS

We searched the following databases in February 2015: the Menstrual Disorders and Subfertility Group (MDSG) Specialised Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, PsycINFO, the Cochrane Central Register of Controlled Trials (CENTRAL) and trial registries. We handsearched relevant journals, conference proceedings and grey literature sources and we contacted pharmaceutical companies for information.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of the use of barrier agents compared with other barrier agents, placebo or no treatment for the prevention of adhesions in women undergoing gynaecological surgery.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for eligibility and risk of bias and extracted the data. We calculated odds ratios (ORs) or mean differences (MD) with 95% confidence intervals (CIs) using a fixed effect model. The overall quality of the evidence was assessed using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) methods.

MAIN RESULTS

Eighteen RCTs (1262 women) were included. Six RCTs randomised women; the remainder randomised pelvic organs. Laparoscopy (eight RCTs) and laparotomy (10 RCTs) were the primary surgical techniques. Indications for surgery included myomectomy (six RCTs), ovarian surgery (five RCTs), pelvic adhesions (five RCTs), endometriosis (one RCT) and mixed (one RCT). The sole indication for surgery in three of the RCTs was infertility. Twelve RCTs reported commercial funding; the rest did not state their source of funding.No studies reported either of our primary outcomes of pelvic pain and live birth. Oxidised regenerated cellulose (Interceed) versus no treatment at laparoscopy or laparotomy (13 RCTs)At second-look laparoscopy oxidised regenerated cellulose at laparoscopy was associated with reduced incidence of de novo adhesions (OR 0.50, 95% CI 0.30 to 0.83, three RCTs, 360 participants, I(2) = 75%, very low-quality evidence) and of re-formed adhesions (OR 0.17, 95% CI 0.07 to 0.41, three RCTs, 100 participants, I(2) = 36%, low quality evidence).At second-look laparoscopy no evidence was found of any difference between the groups in the incidence of de novo adhesions after laparotomy (OR 0.72, 95% CI 0.42 to 1.25, one RCT, 271 participants, I(2) = 41%, low-quality evidence). However, the incidence of re-formed adhesions was lower in the intervention group (OR 0.38, 95% CI 0.27 to 0.55, six RCTs, 554 participants, moderate-quality evidence). Expanded polytetrafluoroethylene (Gore-Tex) versus no treatment at gynaecological surgery (one RCT) The evidence suggested that at second-look laparoscopy expanded polytetrafluoroethylene was associated with a reduction in new adhesion formation (OR 0.17, 95% CI 0.03 to 0.94, one RCT, 42 participants, low-quality evidence). Expanded polytetrafluoroethylene (Gore-Tex) versus oxidised regenerated cellulose (Interceed) at gynaecological surgery (two RCTs)One RCT found no difference between the groups at second-look laparoscopy in the incidence of de novo adhesions (OR 0.93, 95% CI 0.26 to 3.41, 38 participants, very low-quality evidence). A second RCT suggested that the expanded polytetrafluoroethylene group had a lower adhesion score (out of 11) (MD -3.79, 95% CI -5.12 to -2.46, 62 participants, very low-quality evidence) and a lower risk of re-formed adhesions (OR 0.13, 95% CI 0.02 to 0.80, 23 participants, very low-quality evidence). This last finding was sensitive to choice of effect estimate and no longer suggested a difference between the groups when a risk ratio was calculated (RR 0.36, 95% CI 0.13 to 1.01). Sodium hyaluronate and carboxymethylcellulose (Seprafilm) versus no treatment at gynaecological surgery (one RCT)Sodium hyaluronate and carboxymethylcellulose was associated with a lower adhesion score (out of 4) at second-look laparoscopy (MD 0.49, 95% CI 0.53 to 0.45, one RCT, 127 participants, moderate-quality evidence). Fibrin sheet versus no treatment at laparoscopic myomectomy (one RCT)There was no evidence of a difference between the groups in the incidence of de novo adhesions at second-look laparoscopy (OR 1.20, 95% CI 0.42 to 3.41, one RCT, 62 participants) or in adhesion score (out of 4) (MD 0.14, 95% CI -0.67 to 0.39, one RCT, 48 participants, low-quality evidence).Fourteen of the 18 RCTs reported adverse events. No events directly attributed to adhesion agents were reported.

AUTHORS' CONCLUSIONS

We found no evidence on the effects of barrier agents used during pelvic surgery on either pain or fertility outcomes in women of reproductive age.Low quality evidence suggests that oxidised regenerated cellulose (Interceed), expanded polytetrafluoroethylene (Gore-Tex) and sodium hyaluronate with carboxymethylcellulose (Seprafilm) may all be more effective than no treatment in reducing the incidence of adhesion formation following pelvic surgery. There is no conclusive evidence on the relative effectiveness of these interventions. There is no evidence to suggest that fibrin sheet is more effective than no treatment. No adverse events directly attributed to the adhesion agents were reported. The quality of the evidence ranged from very low to moderate. The most common limitations were imprecision and poor reporting of study methods. Most studies were commercially funded, and publication bias could not be ruled out.

Management of intrauterine adhesions: a novel intrauterine device

Intrauterine adhesions (IUAs) are a rare but significant cause of menstrual disturbance and infertility. Most cases are caused by uterine instrumentation. Several methods have been used to prevent IUAs in the past, which can be divided into two groups: pharmacological treatment and physical barrier. However, even with the liberal use of ancillary treatments to minimize reformation of adhesions, IUAs have a high rate of recurrence. Furthermore, medical literature of the last decades has only dedicated great attention to the restoration of normal anatomy in the uterine cavity, but not on the function of the endometrium. When the lesion of the endometrium is severe, especially intrauterine fibrosis, few basal layer is left which contains plenty stem cells to regenerate functional endometrium. Loss of endometrial stem cells directly causes the proliferation of fibrous tissue and subsequent synechiae. None of current treatments can compensate the defect of loss of stem cells. On the basis of existing researches, a novel intrauterine device (IUD) is recommended in this article. The new IUD consists of a light frame which contains two isolated drug-releasing system, one for estrogen and the other for cytokines to promote regeneration of endometrium such as growth factors, and a membrane in the middle of the frame which is also the carrier of endometrium stem cell. This device not only helps to preserve the original anatomy of the uterine cavity, but also to recover the function of endometrium. Experimental and clinical studies are now needed to testify the efficiency of the novel IUD in the prevention of IUAs. If there is a marked reduction in the IUAs and/or improvement of pregnancy success in the case group compared with the control group, our hypothesis will be confirmed.

Pathogenesis, consequences, and control of peritoneal adhesions in gynecologic surgery: a committee opinion

Postoperative adhesions are a natural consequence of surgical tissue trauma and healing and may result in infertility, pain, and bowel obstruction. Adherence to microsurgical principles and minimally invasive surgery may help to decrease postoperative adhesions. Some surgical barriers have been demonstrated effective for reducing postoperative adhesions, but there is no substantial evidence that their use improves fertility, decreases pain, or reduces the incidence of postoperative bowel obstruction. This document replaces the document of the same name last published in 2008 (Fertil Steril 2008;90[5 Suppl]:S144-9).

The use of polytetrafluoroethylene to facilitate the vascular access in recurrent melanoma to limbs

INTRODUCTION

Melanoma with recurrent loco-regional metastases to limbs often makes difficult a second surgical approach because of the adhesions affecting the vascular access. Our aim was to evaluate whether the placement of a polytetrafluoroethylene (PTFE) membrane around vessels might facilitate a surgical re-approach.

PRESENTATION OF CASE

We reported a case of a 64-year-old male with a melanoma on the left foot who developed in transit metastases after LND. While performing the inguinopelvic LND we coated the iliac vessels with PTFE patch to facilitate the vascular access in case of re-intervention for a ILP. In the second surgical approach we made a cutaneous incision in the left iliac region and we proceeded through the subcutaneous tissue until detection of iliac vessels, more clearly visible because of the PTFE patch fixed around vascular walls to minimize adhesions. We removed the PTFE coating and easily performed arteriotomy and venotomy for the completion of the ILP.

DISCUSSION

This case report seems to demonstrate the efficacy of a PTFE membrane applied in a patient around iliac vessels during inguinopelvic dissection, to reduce adhesion density. In fact this membrane provided a barrier to adhesions of the iliac vessels, decreasing the risk of vascular injury thereby facilitating a subsequent vascular access. Re-coating of the iliac vessels with PTFE could be preparatory to a better identification of the vascular structures in cases of a surgical re-approach.

CONCLUSION

The use of PTFE effectively simplifies the second approach to vessels in event of a melanoma metastasizing to limbs.

Current strategies and future perspectives for intraperitoneal adhesion prevention

INTRODUCTION

The formation of peritoneal adhesions still is a relevant clinical problem after abdominal surgery. Until today, the most important clinical strategies for adhesion prevention are accurate surgical technique and the physical separation of traumatized serosal areas. Despite a variety of barriers which are available in clinical use, the optimal material has not yet been found.

DISCUSSION

Mesothelial cells play a crucial physiological role in friction less gliding of the serosa and the maintenance of anantiadhesive surface. The formation of postoperative adhesions results from a cascade of events and is regulated by various cellular and humoral factors. Therefore, optimization or functionalization of barrier materials by developments interacting with this cascade on a structural or pharmacological level could give an innovative input for future strategies in peritoneal adhesion prevention. For this purpose, the proper understanding of the formal pathogenesis of adhesion formation is essential. Based on the physiology of the serosa and the pathophysiology of adhesion formation, the available barriers in current clinical practice as well as new innovations are discussed in the present review.

Intraperitoneal adhesions--an ongoing challenge between biomedical engineering and the life sciences

Peritoneal adhesions remain a relevant clinical problem despite the currently available prophylactic barrier materials. So far, the physical separation of traumatized serosa areas using barriers represents the most important clinical strategy for adhesion prevention. However, the optimal material has not yet been found. Further optimization or pharmacological functionalization of these barriers could give an innovative input for peritoneal adhesion prevention. Therefore, a more complete understanding of pathogenesis is required. On the basis of the pathophysiology of adhesion formation the main barriers currently in clinical practice as well as new innovations are discussed in the present review. Physiologically, mesothelial cells play a decisive role in providing a frictionless gliding surface on the serosa. Adhesion formation results from a cascade of events and is regulated by a variety of cellular and humoral factors. The main clinically applied strategy for adhesion prevention is based on the use of liquid or solid adhesion barriers to separate physically any denuded tissue. Both animal and human trials have not yet been able to identify the optimal barrier to prevent adhesion formation in a sustainable way. Therefore, further developments are required for effective prevention of postoperative adhesion formation. To reach this goal the combination of structural modification and pharmacological functionalization of barrier materials should be addressed. Achieving this aim requires the interaction between basic research, materials science and clinical expertise.

Sunitinib inhibits postoperative adhesions in a rabbit model

BACKGROUND

Postoperative abdominal adhesions are a major cause of morbidity and mortality. We previously demonstrated the inhibitory effect of sunitinib, a receptor tyrosine kinase inhibitor, on adhesion formation in a murine model, and now investigate its effects in a rabbit model.

METHODS

Forty New Zealand White rabbits underwent a standard adhesion procedure. Preoperatively, animals were randomized to treatment with sunitinib or saline (control). Animals were treated with a total of 11 daily doses, 1 preoperative and 10 postoperative. One group of 20 animals (group 1) was humanely killed on postoperative day 10, and the other (group 2) on postoperative day 30. After killing, adhesions were scored and abdominal wounds were collected for tensile strength and microvessel density measurements.

RESULTS

Sunitinib-treated animals in group 1 had a mean tenacity score of 1.67 ± 0.29 compared with 3.60 ± 0.16 in control animals (P < .01). Similarly, the mean tenacity scores for sunitinib-treated and control animals in group 2 were 0.20 ± 0.20 and 2.70 ± 0.37, respectively (P < .01). The mean uterine involvement scores for sunitinib-treated and control animals in group 1 were 1.44 ± 0.29 and 3.70 ± 0.15, respectively (P < .01), and in group 2 were 0.10 ± 0.10 and 2.70 ± 0.45, respectively (P < .01). There were no differences in ultimate or modular wound tensile strength between sunitinib-treated and control animals.

CONCLUSION

Sunitinib significantly reduces postoperative adhesions in a rabbit model. This therapy may improve postoperative adhesion-related morbidity and mortality.

Administration of a novel penicillamine-bound membrane: a preventive and therapeutic treatment for abdominal adhesions

BACKGROUND

Adhesions formation is a significant postsurgical complication. At present, there is no effective method for preventing adhesions formation 1, although barrier products such as Dextran (Dex) 2 and sodium hyaluronate (SH) 3 have proved the most clinically successful 456, This study is designed to investigate the preventive and therapeutic potential of a novel penicillamine-bound membrane for abdominal adhesions formation.

METHODS

150 rats were involved in the present study. All animals were randomly divided into 6 groups (1 vehicle group and 5 test groups respectively treated with dextran, sodium hyaluronate, penicillamine, penicillamine-bound membrane or non-penicillamine-bound membrane). The occurrence, grade and score of abdominal adhesions were compared between the different groups. The breaking strength of incision was compared between the vehicle group and the penicillamine, membrane with/without penicillamine - treated groups. Expression of collagen type I was compared between the vehicle and penicillamine-treated group. The occurrence of adhesions was compared between the Dextran (Dex), sodium hyaluronate (SH), penicillamine-treated group and membrane with or without penicillamine- treated groups.

RESULTS

Penicillamine and penicillamine-bound membrane had significant preventive effects on abdominal adhesions formation, better than dextran, sodium hyaluronate and non-penicillamine-bound membrane. However, neither of them influenced incision healing, although they insignificantly decreased the breaking strength of the incision. Penicillamine-bound membrane, which can be loaded locally and more efficaciously, shows greater advantages than penicillamine.

CONCLUSIONS

Penicillamine-bound membrane can be applied as an effective therapeutic intervention for abdominal adhesions with inconsequential side effects.

Peritoneal adhesions in human and veterinary medicine: from pathogenesis to therapy. A review

Any peritoneal inflammatory process consequent to infections or surgical injuries may induce abdominal adhesion formation. Peritoneal adhesions are connective laciniae that develop among abdomino-pelvic organs that limit physiologic visceral motion. Consequently, fertility may be impaired, and intestinal obstruction and pelvic pain may develop, mainly in subjects that had undergone gynaecological surgery. This review illustrates the pathogenic steps of adhesiogenesis and the therapeutic scenario that evolved over the years to tackle the threat of peritoneal adhesions, both in domestic animals and in women.

A prospective, randomised, controlled, double-blind phase I-II clinical trial on the safety of A-Part Gel as adhesion prophylaxis after major abdominal surgery versus non-treated group

Background

Postoperative adhesions occur when fibrous strands of internal scar tissue bind anatomical structures to one another. The most common cause of intra-abdominal adhesions is previous intra-abdominal surgical intervention. Up to 74% of intestinal obstructions are caused by post surgical adhesions. Although a variety of methods and agents have been investigated to prevent post surgical adhesions, the problem of peritoneal adhesions remains largely unsolved. Materials serving as an adhesion barrier are much needed.

Methods/Design

This is a prospective, randomised, controlled, patient blinded and observer blinded, single centre phase I-II trial, which evaluates the safety of A-Part^® Gel as an adhesion prophylaxis after major abdominal wall surgery, in comparison to an untreated control group. 60 patients undergoing an elective median laparotomy without prior abdominal surgery are randomly allocated into two groups of a 1:1- ratio. Safety parameter and primary endpoint of the study is the occurrence of wound healing impairment or peritonitis within 28 (+10) days after surgery. The frequency of anastomotic leakage within 28 days after operation, occurrence of adverse and serious adverse events during hospital stay up to 3 months and the rate of adhesions along the scar within 3 months are defined as secondary endpoints. After hospital discharge the investigator will examine the enrolled patients at 28 (+10) days and 3 months (±14 days) after surgery.

Discussion

This trial aims to assess, whether the intra-peritoneal application of A-Part^® Gel is safe and efficacious in the prevention of post-surgical adhesions after median laparotomy, in comparison to untreated controls.

Trial registration

NCT00646412

Prevention of intra-peritoneal adhesions in gynaecological surgery: theory and evidence

Post-operative adhesions are a significant complication of all abdominal surgical procedures. The major strategies for adhesion prevention in gynaecological surgery are focused on the optimization of surgical technique and use of anti-adhesive agents, which fall into two main categories: pharmacological agents and barriers. Surgical technique that minimizes peritoneal trauma can reduce, but cannot prevent post-operative adhesion formation. Various local and systemic drugs that can alter the local inflammatory response, inhibit the coagulation cascade and promote fibrinolysis have been evaluated. Limited data support the administration of post-operative corticosteroids in addition to systemic intra-operative corticosteroids for the prevention of adhesions after gynaecological surgery. None of the remaining pharmacological agents have been found effective for the reduction of post-operative adhesions. Barriers are currently considered the most useful adjuncts, which may reduce adhesion formation. They act by separating the traumatized peritoneal surfaces during the healing period. The separation can be achieved by solid barriers or fluids. There is limited evidence from randomized clinical trials that support the beneficial effect of most of these barrier agents in the prevention of intra-peritoneal adhesions after gynaecological surgery. However, the evidence is not adequate for definite conclusions to be drawn and further research in this field is warranted.

Postsurgical adhesion formation and prevention – recent developments with regard to the consecutive stages in adhesion formation

The formation of adhesions is a significant clinical problem. Complications like bowel obstruction and chronic pelvic pain are known to be related to adhesion formation. Besides these complications, adhesions do play an additional role in the gynaecological patient. Interference with the functioning of the fallopian tubes and ovaries disturbs ovum pickup and sperm transport and may compromise the fertility of patients.

Pathogenesis, consequences, and control of peritoneal adhesions in gynecologic surgery

Postoperative adhesions are a natural consequence of surgical tissue trauma and healing and may result in infertility, pain, and bowel obstruction. Adherence to microsurgical principles, minimally invasive surgery, and use of some peritoneal instillates may help to decrease postoperative adhesions. Some surgical barriers have been demonstrated effective for reducing postoperative adhesions, but there is no substantial evidence that their use improves fertility, decreases pain, or reduces the incidence of postoperative bowel obstruction.

Barrier agents for adhesion prevention after gynaecological surgery

BACKGROUND

Pelvic adhesion can form as a result of inflammation, endometriosis or surgical trauma. During pelvic surgery, strategies to reduce pelvic adhesion formation may include placing synthetic barrier agents such as oxidised regenerated cellulose, polytetrafluoroethylene or Fibrin sheets between the pelvic structures.

OBJECTIVES

To assess the effect of physical barriers used during pelvic surgery in women of reproductive age on pregnancy rates, pelvic pain, or postoperative adhesion reformation.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group Trials Register (searched September 2007) which is based on regular searches of MEDLINE, EMBASE, CINAHL, PsycINFO and CENTRAL, plus handsearching of 20 relevant journals and conference proceedings, and searches of several key grey literature sources. In addition, companies were contacted for unpublished trials.

SELECTION CRITERIA

Any randomised controlled trials (RCTs) comparing the use of physical barriers versus no treatment or other physical barriers in the prevention of adhesions in women undergoing gynaecological surgery.

DATA COLLECTION AND ANALYSIS

Review authors assessed trial eligibility and quality.

MAIN RESULTS

Sixteen RCTs were included. Five trials randomised patients while the remainder randomised pelvic organs. Laparoscopy (six trials) and laparotomy (10 trials) were the primary surgical techniques. Indications for surgery included myomectomy (five trials), ovarian surgery (five trials), pelvic adhesions (four trials), endometriosis (one trial), and mixed (one trial). Eleven trials assessed Interceed versus no treatment, two assessed Interceed versus Gore-Tex, one trial assessed Gore-Tex versus no treatment, and one trial assessed Seprafilm versus no treatment. A single trial assessed Fibrin sheet versus no treatment. No studies reported pregnancy or reduction in pain as outcomes. The use of Interceed was associated with reduced incidence of pelvic adhesion formation, both new formation and reformation following laparoscopic surgery or laparotomy. However, this result should be interpreted with caution. Gore-Tex was more effective than no barrier or Interceed in preventing adhesion formation. There was only limited evidence that Seprafilm was effective in preventing adhesion formation following myomectomy and no evidence to support Fibrin sheet.

AUTHORS' CONCLUSIONS

The absorbable adhesion barrier Interceed reduces the incidence of adhesion formation following laparoscopy and laparotomy, but there are insufficient data to support its use to improve pregnancy rates. Gore-Tex may be superior to Interceed in preventing adhesion formation but its usefulness is limited by the need for suturing and later removal. There was no evidence of effectiveness of Seprafilm and Fibrin sheet in preventing adhesion formation.

Pathogenesis, consequences, and control of peritoneal adhesions in gynecologic surgery

Postoperative adhesions are a natural consequence of surgical tissue trauma and healing and may result in infertility, pain, and bowel obstruction. Adherence to microsurgical principles, minimally invasive surgery, and use of some peritoneal instillates may help to decrease postoperative adhesions. Some surgical barriers have been demonstrated effective for reducing postoperative adhesions, but there is no substantial evidence that their use improves fertility, decreases pain, or reduces the incidence of postoperative bowel obstruction.

Prevention of adhesions in gynaecological endoscopy

Adhesions resulting from gynaecological endoscopic procedures are a major clinical, social and economic concern, as they may result in pelvic pain, infertility, bowel obstruction and additional surgery to resolve such adhesion-related complications. Although the minimally invasive endoscopic approach has been shown to be less adhesiogenic than traditional surgery, at least with regard to selected procedures, it does not totally eliminate the problem. Consequently, many attempts have been made to further reduce adhesion formation and reformation following endoscopic procedures, and a wide variety of strategies, including surgical techniques, pharmacological agents and mechanical barriers have been advocated to address this issue. The present review clearly indicates that there is no single modality proven to be unequivocally effective in preventing post-operative adhesion formation either for laparoscopic or for hysteroscopic surgery. Furthermore, the available adhesion-reducing substances are rather expensive. Since excellent surgical technique alone seems insufficient, further research is needed on an adjunctive therapy for the prevention and/or reduction of adhesion formation following gynaecological endoscopic procedures.

Control and prevention of peritoneal adhesions in gynecologic surgery

Postoperative adhesion formation is a natural consequence of surgical tissue trauma and healing and may result in infertility, pain, and bowel obstruction. Microsurgical principles and minimally invasive surgery may help decrease adhesion formation, but anti-inflammatory agents and peritoneal instillates have no demonstrable benefit. Although some surgical barriers are effective for reducing postoperative adhesions, none has been shown to improve fertility or to decrease pain or the incidence of postoperative bowel obstruction.

In vivo performance of antibiotic embedded electrospun PCL membranes for prevention of abdominal adhesions

The aim of this study was to prepare nonwoven materials from poly(epsilon-caprolactone) (PCL) and their antibiotic containing forms by electrospinning, so as to prevent postsurgery induced abdominal adhesions in rats. epsilon-Caprolactone was first polymerized by ring-opening polymerization, and then it was processed into matrices composed of nanofibers by electrospinning. A model antibiotic (Biteral) was embedded within a group of PCL membranes. In the rat model, defects on the abdominal walls in the peritoneum were made to induce adhesion. The plain or antibiotic embedded PCL membranes were implanted on the right side of the abdominal wall. No membrane implantation was made on the left side of the abdominal wall that served as control. Macroscopical and histological evaluations showed that using these barriers reduces the extent, type, and tenacity of adhesion. The antibiotic embedded membranes significantly eliminated postsurgery abdominal adhesions, and also improved healing.

Conservative Surgical Management of Uterine Myomas

Uterine fibroids are a major gynecologic problem in American women, and several alternatives have been developed. Conservative treatment, with the goal of treating the fibroid but retaining the uterus, is a frequent choice among women who require therapy during their early to middle reproductive years. A variety of conservative surgical approaches exist; each has advantages and disadvantages for the clinician and the patient. Some are well-established techniques, whereas others are still in the investigational stage. None has been evaluated adequately for its effects on future fertility. To this end, it is imperative that investigators continue to evaluate these surgical procedures so that the clinician can provide accurate and comprehensive information when faced with a patient who desires one or more of these approaches. Furthermore, it is critical for the practitioner to stay informed about these procedures so that patients can be given a full complement of options.

Morphological changes in the anterior abdominal wall of rats with peritonitis and implanted synthetic film

Histological study and electron microscopy of the anterior abdominal wall and laparotomy wound closed using a polytetrafluoroethylene film was performed on rats with experimental peritonitis. We studied 4 types of polytetrafluoroethylene films differing in the size of micropores and technology of treatment. The tissue response differed after implantation of various films. A multilayer film with minimum size of pores was optimal to repair the laparotomy wound.

Prevention of postsurgical tissue adhesion by anti-inflammatory drug-loaded pluronic mixtures with sol-gel transition behavior

Sol-gel transition temperature-controllable Pluronic F127/F68 mixtures including mildly crosslinked alginate and nonsteroidal anti-inflammatory drug (ibuprofen) were prepared to evaluate their potential as tissue adhesion barrier gels. The sol-gel transition temperatures of the Pluronic mixtures could be controlled by adjusting F127/F68 ratio and polymer concentration. The mildly crosslinked alginate with still flow property provided the residence stability of Pluronic mixture gels in the body. Ibuprofen was loaded in Pluronic mixtures to reduce inflammatory response in the body and, thus, to prevent tissue adhesion. The gelation temperatures of the Pluronic mixtures were not affected by the alginate but lowered by the addition of ibuprofen. The in vitro drug release behavior and in vivo peritoneal tissue adhesion of the Pluronic mixtures with the sol-gel transition just below body temperatures were investigated. The drug release behavior from the ibuprofen (1 wt%)-loaded Pluronic mixture gels at 37 degrees C was examined using a membrane-less dissolution model. The drug in the mixture gels was released continuously up to about 45-65% of the total loading amount during the first 7 days. For in vivo evaluation of tissue anti-adhesion potential, the Pluronic mixtures with/without drug were coated on the peritoneal wall defects of rats and their tissue adhesion extents and tissue reactions (inflammatory response, granulation tissue formation, and toxicity in organs) were compared. It was observed that ibuprofen has a positive effect for the peritoneal tissue anti-adhesion. The Pluronic F127/F68/alginate/ibuprofen mixture gel (25 wt% of F127/F68 [7/3], 1 wt% ibuprofen) was highly effective for the prevention of peritoneal tissue adhesion and showed a relatively low inflammatory response and non-toxicity, and thus can be a good candidate material as a coatable or injectable tissue adhesion barrier gel.

Seprafilm superior to Gore-Tex in the prevention of peridural fibrosis

OBJECT

This is an investigation into the effects of two barrier membranes in the prevention of peridural fibrosis in an animal model.

METHODS

Seprafilm or Gore-Tex was applied to a laminectomy defect overlying the dura mater in rats separated into treatment groups. A third group of rats underwent laminectomy only and served as controls. Two months postoperatively a histological study was performed to compare the amount of scar tissue in each group. The gross dissection demonstrated that both membranes created a controlled dissection plane, facilitated access to the epidural space, and provided a reduction in the amount of tissue adhering to the dura mater. Statistically, Seprafilm was superior to Gore-Tex in preventing peridural fibrosis (p < 0.05).

CONCLUSIONS

Seprafilm can prevent peridural fibrosis better than Gore-Tex and can be used in humans in spinal surgery.

Adhesion prevention in gynecologic surgery

The objectives of this study are to evaluate the magnitude of postsurgical adhesions clinically, their impact on the hospital budget, and the available adhesion-reducing substances. We conducted a review of relevant literature on intraabdominal adhesion, adhesion-reducing substances, and their related cost. The relevance of adhesions to gynecology not only relates to infertility and abdominal pain, but also to the occurrence of bowel obstruction. There have been many substances and materials used to decrease the adhesion formation. However, there is still no adhesion-reducing substance that is unequivocally effective. Its use is also costly. The most common cause of small-bowel obstruction is postsurgical adhesions. Indeed, more than one half of patients with adhesion-related small-bowel obstruction had previous gynecologic operations, and a high percentage occurs after abdominal hysterectomy. To date, there has been no study suggesting that the use of adhesion-reducing substances decreases the risk of bowel obstruction or the long-term costs to the healthcare system. The long-awaited substance or barrier that unequivocally prevents adhesion formation is yet to come.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to list the causes of small bowel obstruction, to describe the commercially available adhesion-reducing substances, and to compare the efficacy of the various adhesion-reducing substances.

A neurokinin 1 receptor antagonist decreases postoperative peritoneal adhesion formation and increases peritoneal fibrinolytic activity

Fibrous adhesions remain a major sequela of abdominal surgery. The proinflammatory peptide substance P (SP), known to participate in inflammatory events, may play a key role in adhesion formation. This hypothesis was tested by using an antagonist, CJ-12,255 (Pfizer), that blocks the binding of SP to the neurokinin 1 receptor (NK-1R). Adhesion formation was surgically induced in the peritoneum of rats receiving daily doses of the NK-1R antagonist (NK-1RA; 5.0 or 10.0 mg/kg per day) or saline. On postoperative day 7, both the low and high doses of NK-1RA significantly (P < 0.05) reduced adhesion formation by 45% and 53%, respectively, compared with controls. Subsequently, the effect of NK-1RA administration on peritoneal fibrinolytic activity was investigated to determine a potential mechanism for SP action in the peritoneum. Samples were collected from nonoperated controls and from animals 24 h postsurgery that were administered either NK-1RA or saline. Fibrinolytic activity in peritoneal fluid was assayed by zymography, and expression of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1, both regulators of fibrinolytic activity, was assessed in peritoneal tissue and fluid by RT-PCR and bioassay, respectively. NK-1RA administration led to a marked (P < 0.05) increase in tPA mRNA levels in peritoneal tissue compared with nonoperated and saline-administered animals. Likewise, NK-1RA administration significantly (P < 0.05) increased tPA in the peritoneal fluid. These data suggest that activation of the NK-1R promotes peritoneal adhesion formation by limiting fibrinolytic activity in the postoperative peritoneum, thus enabling fibrinous adhesions to persist.

Prevention and treatment of gastrointestinal adhesions

As with many aspects of clinical medicine, there is yet to be a single or definitive cure for postoperative adhesion formation. Current methods of prevention target risk factors predisposing horses to adhesion formation. Systemic pharmacologic therapies, such as antimicrobials, nonsteroidal anti-inflammatory drugs, Salmonella antiserum, and hyperimmune plasma, help to reduce abdominal inflammation and minimize the effects of endotoxemia. Intra-abdominal or systemic heparin aids in enhancing peritoneal fibrinolysis. Prokinetic therapy promotes early postoperative return of intestinal motility, minimizing the propensity for adhesion formation between apposing adynamic segments of intestine. Mechanical separation of potentially adhesiogenic serosal and peritoneal surfaces is commonly achieved with use of abdominal lavage, protective coating solutions, and barrier membranes. Ongoing and future research is directed toward a better understanding of the local effects of intestinal trauma and the corresponding response of the fibrinolytic system. Recognition of horses at high risk for adhesion formation helps to guide the equine surgeon to an appropriate perioperative and intraoperative plan for adhesion prevention, including good surgical technique and a combination of adjunct therapies.

Collagen-PVP, a collagen synthesis modulator, decreases intraperitoneal adhesions

BACKGROUND

Adhesion formation in the peritoneal cavity is the most common cause of intestinal obstruction and secondary female infertility. A great effort has been dedicated to reduce adhesion formation because of the associated morbidity and its complications.

MATERIALS AND METHODS

This study was designed as a before-after comparative trial and included 14 rabbits, with a weight between 300 and 500 g. All rabbits were appendectomized and 1 month later laparotomized to assess adhesion formation. Rabbits were randomized into two groups, Group I (control group), with no intervention, and Group II (experimental group), treated with an intraperitoneal sponge of collagen-polyvinylpyrrolidone (Clg-PVP). The laparotomy procedure was repeated 1 month later for a new assessment of adhesion formation and histological evaluation by H-E and Masson staining.

RESULTS

Histological findings showed abundant infiltrate in the control group, which was mild in the experimental group. With the Masson stain the control group showed a significantly higher amount of collagen than the experimental group and the fibrous tissue was more compact. We found a mean number of adhesions of 3.29 +/- 1.98 for the control group, which decreased to 2.57 +/- 0.79 after the second laparotomy. For the experimental group the mean number of adhesions decreased from 1.86 +/- 0.90 to 0.71 +/- 0.49 after the second laparotomy, with no statistical difference between both groups before Clg-PVP application, but a significant statistical difference after the implantation of Clg-PVP (Student's t test; P < 0.001, two-tailed).

CONCLUSION

Collagen-polyvinylpyrrolidone decreases the incidence and size of intraabdominal adhesions after secondary adhesion formation after appendectomy.

Evaluation of the antiadhesion potential of UV cross-linked gelatin films in a rat abdominal model

Among five kinds of rat adhesion models tested, the following model was selected. The epigastric vein 2.5 cm from the midline of the abdomen was cut by sharp scissors, and the lateral side of the cut epigastric vein was ligated using a 3-0 silk suture. This model could be easily prepared and gave a rate of adhesion formation of 90%, which was useful for screening antiadhesive materials. For the kinetic study of tissue adhesion in this model, an injured site was covered with a non-degradable poly(vinyl alcohol) (PVA) film. The incidence rate of adhesion was 18%, when the PVA film covered the injured site for 2 days. This suggests that an antiadhesive barrier should cover the injured site for at least 2 days. The antiadhesion efficacy of cross-linked gelatin films were evaluated using this adhesion model. The UV cross-linked gelatin film which was designed to exist for 2 days but to disappear at day 3 in the rat abdominal cavity showed the highest antiadhesion efficacy.