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European Commission Final Opinion on: The safety of surgical meshes used in urogynecological surgery
Surgical meshes have been used since the 1950s to repair abdominal hernias and were then used in the 1990s for the treatment of male and female stress urinary incontinence (SUI), female pelvic organ prolapse (POP) and colorectal functional disorders (CFD). More recently the use of synthetic mesh and biological materials has become common, requiring new surgical insertion tools and tissue fixation anchors.
The use of meshes in surgery has been shown to be associated with various adverse complications such as infection, tissue extrusion, separation of vaginal epithelium leading to visualisation of the mesh (mesh exposure), mesh shrinkage and adverse side effects including pain and sexual dysfunction. The European Commission has, thus, requested the SCENIHR to assess the health risks of meshes used in urogynaecological surgery.
The various options for the treatment of pelvic floor dysfunctions were reviewed based on the scientific literature and the guidelines from scientific societies and health authorities. Included were both non-surgical and surgical treatment methods.
Non-biological surgical mesh materials can be divided into three categories: non- absorbable synthetics, absorbable synthetics, and composites. Synthetic meshes that have been used with mono- or multi-filament structure are usually classified according to their mesh size as Types 1, 2, 3 or 4 (Amid Classification), where type 1 is with pores >75 μm, type 2 with pores <10μm, type 3 with micropores and type 4 with monofilaments and submicronic pores of <1μm. Today, type 1 polypropylene mesh is the most commonly used.
Clinical outcome following mesh implantation is influenced by material properties, product design, overall mesh size, route of implantation, patient characteristics, associated procedures (e.g. hysterectomy) and the surgeon’s experience. The SCENIHR recommends that such aspects should be taken into account when choosing an appropriate therapy.
In assessing the risk associated with mesh application, it is important to consider the overall surface area of material used, the product design and the properties of the material used. The available evidence suggests a higher morbidity in treating POP, which uses a much larger amount of mesh compared to SUI.
When assessing synthetic mesh risks, there is a need to clearly distinguish between the risks associated with SUI sling surgery and those of POP mesh surgery; sling surgery for SUI is associated with lower risks compared to POP mesh surgery.
The implantation of any mesh for the treatment of POP via the vaginal route should only be considered in complex cases, in particular, after failed primary repair surgery. Mesh exposure rates for vaginal POP surgery with mesh range from 4 to 19% (Milani et al., 2013). The use of autologous graft material is not feasible for POP because of the large mesh area required and the resulting donor morbidity. The use of absorbable mesh inserted either via a transabdominal or transvaginal route is associated with a high failure rate. Transvaginal surgery using non-absorbable synthetic mesh for POP involves a much greater surface area of mesh and is associated with a higher risk of mesh-related morbidity than seen with transabdominal insertion of mesh. Sacrocolpopexy is associated with greater surgical morbidity compared to vaginal repair.
In sling surgery, there is evidence that absorbable biological materials have a high failure rate while sling surgery with non-absorbable synthetic mesh was effective with an approximately mesh exposure rate of 4% (Brubaker et al., 2011). Autologous slings are a more invasive alternative (because of the need to harvest native tissue), but they also can be inserted using a minimally invasive approach. The traditional surgical approach of colposuspension is associated with greater morbidity compared to sling surgery with mesh.
However, synthetic sling SUI surgery is an accepted procedure with proven efficacy and safety in the majority of patients with moderate to severe SUI, when used by an experienced and appropriately trained surgeon. Therefore, the SCENIHR supports continuing synthetic sling use for SUI, but emphahsises the importance of appropriately trained surgeons and detailed counselling of patients about the associated risk/benefits.
Based on the available scientific evidence, the SCENIHR recommends
the implantation of any mesh for the treatment of POP via the vaginal route should be only considered in complex cases in particular after failed primary repair surgery,
that due to increased risks associated with the use of synthetic mesh for POP repair via a trans-vaginal route, this option should only be used when other surgical procedures have already failed or are expected to fail.
limiting the amount of mesh for all procedures where possible. However, there is a need for further improvement in the composition and design of synthetic meshes, in particular for POP surgery.
the introduction of a certification system for surgeons based on existing international guidelines and established in cooperation with the relevant European Surgical Associations.
appropriate patient selection and counselling, which is of paramount importance for the optimal outcome for all surgical procedures, particularly for the indications discussed. This should be based on the results of further clinical evidence, which should be collected in a systematic fashion for all of these devices.