Pelvic organ prolapse (POP) is an increasingly common female health problem which, when symptomatic, has a significant negative impact on all aspects of daily life. Treatment is commonly surgical and should aim not only at restoring anatomy but also at alleviating symptoms, improving long-term pelvic organ function.
The etiology of POP is multifactorial. The end-result, nevertheless, is an inadequate pelvic organ support system. Emerging evidence suggests even a genetic linkage to supporting tissue defects in women with POP. The poor condition of these tissues at the time of surgical intervention provides the rationale for the use of mesh to reinforce repairs.
This article will focus on recent evidence on the pros and cons of using synthetic meshes in POP repairs.
Reasons for using a mesh
The rationale behind the use of mesh is to enhance efficacy of prolapse repairs: improve anatomic support and avoid recurrence. In a recent review of the literature Richter et al. found that native tissue repair of the anterior vaginal compartment is associated with more recurrent anatomic prolapse and increased symptomatic bulging compared with vaginal repair using polypropylene mesh. This finding is in agreement with the 2013 Cochrane review and is further supported by newly published evidence: in a recent prospective randomised controlled trial, women with stage III or IV anterior vaginal wall prolapse were randomised to anterior colporrhaphy with vaginal colposuspension or transvaginal mesh.
Vaginal mesh gave better two-year anatomical results than vaginal colposuspension. In another single- center, randomised, interventional trial of post- hysterectomy vaginal vault prolapse, Prolift Total® was compared to native tissue, unilateral vaginal sacrospinous colpopexy with vaginal repair. On clinical examination at one-year follow-up, only one case of anatomical failure was observed in the Prolift group (3%) compared to 22 (65%) in the sacrospinous colpopexy group.
The above mentioned efficacy benefit is derived from non-absorbable, synthetic mesh. In a randomised controlled trial with 12 months follow-up, anterior compartment pelvic organ prolapse using porcine small intestine submucosa did not confer additional benefit over a native tissue repair, both in terms of anatomic and patient-reported outcomes. This is in accordance with and supported by previously published data: in a meta-analysis of 49 studies involving 4569 women9 non-absorbable synthetic mesh had a significantly lower objective prolapse recurrence compared to absorbable synthetic mesh and biological graft.
Apart from the reinforcement of tissue repairs commercially available mesh kits offer the advantages of “easy” and “fast” repairs.
The clearance of the first transvaginal surgical mesh product designed for pelvic organ prolapse by the Food and Drug Administration (FDA) in 2004, was accompanied by a significant uptake of mesh augmented repairs in the following years. Jonsson Funk et al. utilised adjudicated healthcare claims involving mesh for POP in the USA from 2005 to 2010 and they reported an overall significant increase in vaginal mesh procedures from 36.7 to 60.8 per 100.000 person-years during the study period (Figure 1).
Reasons for not using a mesh
The most important reason for not using a mesh for POP repair is complications: these complications can be related either to the procedure of placing the mesh (such as injuries to the urinary tract, bowel or vessels during trocar/introducer placement) or to the presence of the mesh itself. Among the latter, the most frequently reported are mesh exposure through the vagina (Figures 2-3), pain, infection and dyspareunia. Vaginal scarring/shrinkage and emotional problems are less frequently reported. The above conditions may require additional intervention including medical or surgical treatment and hospitalization.
Figure 2: Recurrent vaginal mesh exposures after TVM
Sometimes complications, especially exposure and shrinkage, can be devastating and require multiple, difficult operations to be managed. The initial uptake in mesh augmented repairs in the years following 2004 was followed by such an important increase in complication reporting that lead to the 2008 FDA issue of a public health notification11 to inform physicians and patients of these adverse events. In the three years that followed, there was a five-fold increase in the number reports associated with mesh for POP, prompting the FDA to release a safety communication in 2011. Finally, in April 2014, the FDA proposed moving total vaginal mesh for POP from class II (low-risk to moderate-risk) to class III (high-risk) (Figure 4).
The FDA reports challenged the rationale of using mesh: they stated that there is no evidence that using mesh during transvaginal repair to support the top of the vagina (apical repair) or the back wall of the vagina (posterior repair) provides any added benefit compared to traditional surgery without mesh. They also stated that the benefit of mesh augmented anterior vaginal wall repair is anatomical and is not associated with better results as far as symptoms relief is concerned. The above mentioned FDA notifications provoked, as expected, different reactions with some urogynecologists abandoning the use of mesh while others continued using it in prolapse repairs.
What to do now?
The best way to face this situation of uncertainty is to critically evaluate it. The first important thing to do is clearly differentiate between SUI and POP surgery and between mesh positioned by the vaginal route and by the abdominal route. The FDA 2014 recommendation to move total vaginal mesh from low- to-moderate risk class to high-risk class specifically excludes mesh when it is used for either stress urinary incontinence (SUI) or trans-abdominal POP repair such as sacrocolpopexy. This does not imply that mesh used during sacrocolpopexy or for treatment of SUI is devoid of complications but the risk is definitely lower.
Another important point is that although mesh complications may be quite bothersome and difficult to treat this is not the rule: about 35% of vaginal mesh exposures are asymptomatic and are found during follow-up clinical examinations, usually within the first months after surgery.
One key in avoiding transvaginal mesh complications is patient selection after weighing benefits against risk for an individual patient. But what patient- prolapse is the best candidate for mesh augmentation repair?
It is reasonable to use mesh in cases of increased risk of prolapse recurrence. Factors associated with recurrence are age less than 60 years, prolapse stage 3 or 4, diabetes mellitus and recurrent prolapse. If mesh is to be used how can the risk of mesh-related complications be minimised? Known risk factors for mesh exposure are lack of experience of the surgeon, delayed infection and injury to adjacent tissue.
Based on the above observations a vaginal approach to prolapse stage at least III, either primary or after recurrence following initial native tissue repair in a young woman is the best indication of mesh augmentation. General, non-specific measures like preoperative obesity management, smoking cessation, and adequate diabetes control may be helpful in reducing the risk for complications. The benefit of using local estrogen is unclear and prevention of perioperative infection with prophylacting antibiotics a must, despite the lack of robust evidence to support it.
After patient selection the choice of mesh to use is another important point. Unfortunately the ideal mesh has not been found yet. Most experts agree that macroporous, low weight, (collagen coated) polypropylene is the material of choice while polyester, polyfilament, microporous, composite mesh should be avoided.
The search for the ideal mesh is continuing and tissue engineered repair material (TERM) may be the future: adipose-derived stem cells could be combined with biodegradable scaffolds to create a TERM that is suitable for SUI and POP treatment, hopefully reducing the risk of mesh related comlications.
In summary, most scientific societies and the FDA agree that the current situation can be overcome by paying attention to surgeon training, proper patient selection and detailed counselling of the patients. In the meantime, mesh kits should be subject to high quality level I research in randomized controlled trials
Prof. Elisabetta Costantini, University of Perugia Dept. of Urology Ospedale Santa Maria della Misericordia, Perugia (IT)
Dr. Konstantinos Giannitsas, Patras University Hospital Department of Urology, Patras (GR)