Transvaginal Mesh in The Anterior Compartment for Treatment of Advanced Cystoceles … My Opinion
Approximately 30% of women in the U.S. are affected by some degree of pelvic organ prolapse (POP) related symptoms. Women are living longer than ever before, and adopting more active lifestyles. Such sustained biomechanical challenges to the pelvic support structures exceed that experienced by women decades ago. Patients with POP have structurally altered collagen, elastin, laminin, and smooth muscle. These factors have challenged the durability of traditional suture-based native tissue repairs (NTR). The 2014 OPTIMAL trial from The Pelvic Floor Disorders Network, skilled surgeons performing suture based NTR, showed that regardless of the native tissue ligament utilized the recurrence rate approached 40%. At the 5-year follow-up, these recurrence rates progressed to 61% and 70% respectively. Any surgery that carries such a high failure rate is unacceptable to our value-based health care system, and especially unacceptable to the individual patient.
Studies have consistently demonstrated significant recurrence rates in patients that have undergone NTR reconstructive surgery, especially in the anterior compartment. The reported rates of repeat operations for recurrence are grossly under-representing the reality of what patients are experiencing. Women often “settle” for a recurrence even though they are once again symptomatic, since symptoms may not be as severe as before. The gradual progression of the recurrence with ensuing troublesome symptoms will often force the patient to eventually seek a re-operation. This real-world scenario over inherent extended time line (several years) is not captured in the limited follow-up reported in the literature.
Evidence-based medicine is defined as “the use of clinical expertise combined with current best evidence to make decisions about the care of individual patients.” The foremost component of evidence-based medicine is the clinical expertise of the provider. This is even more crucial when applied to surgical care. The individual technical skill set of the surgeon, which is the largest contributing factor of the surgical outcome, is not controlled for in our highest grade of clinical trials, the prospective RCT. The reality of the surgeon factor, however, must still be considered when examining the safety and effectiveness of implanted devices.
What about the concerns for infection?
Monofilament polypropylene mesh knitted with a complete macroporous composition will allow for the ingrowth, or incorporation of appropriate cells into the material such as myocytes and fibroblasts. Since the current macroporous monofilament materials do have a small amount of interstices where filaments cross each other, that are in the order of one micron in size, some theorize that bacteria may still elude the infection fighting cells of the body. Recent studies using advanced techniques for assessing both 2D/3D activities of macrophages; have demonstrated these cells have more of an ability to migrate in places previously thought too small.
What about concerns regarding mesh degradation?
The probability of mesh degrading within the female pelvis has now been clearly demonstrated to be untrue. In 2017, researchers addressed the alleged degradation of polypropylene based mesh by properly processing the explants through a nondestructive, hydrolytic cleaning process to remove any bio-film. The authors then supplemented this process with multiple light microscopy, infrared spectroscopy and scanning electron microscopy on 78 explanted Prolene meshes with duration of implantation ranging 0.4 to 11.7 years. The author’s concluded:
“Our effective cleaning of explanted Prolene meshes and subsequent analyses showed that they did not degrade in vivo, confirming the in vivo stability of properly formulated polypropylene. Instead, the cracked layer that some researchers have identified as degraded Prolene is an adsorbed protein–formaldehyde coating, resulting from the well-established formalin–protein fixation process, which occurs immediately upon placing an explant in formalin.”
What about the role of the surgeon factor?
The study design benefits of a RCT, namely that of controlling for confounding variables, does not control for the largest and most important variable, the skill set of the performing surgeon. Although well-recognized by many research experts, this has yet to be accounted for by publishing surgeons. Variations in surgical execution of the studied procedure are rarely analyzed and/or reported once data has been collected. Thus, without analyzing for performance bias, the RCT study design is flawed in surgical trials, therefore the study results provided may be inaccurate and misleading. There is tremendous variation in mesh exposure rates among reporting surgeons, often within the same study, using the same material. A 2017 study closely examined the role of the surgeon on outcomes of vaginal prolapse surgery with mesh. A total of 1,657 surgeries for POP using TVM were reviewed. Surgeons who performed the procedures were classified as low-volume (1 case annually), intermediate-volume (2 cases) or high-volume (3 or more cases). The cumulative reoperation rate one year after TVM repair with mesh was significantly higher for low-volume surgeons. Most surgeries (53%) were performed by the low-volume surgeons. The authors concluded “that surgeon inexperience may have contributed to a significant proportion of mesh-related complications, prompting the first FDA Safety communication in 2008,” and that surgeon experience must be a consideration when reporting POP mesh-related surgery complications.
TVM, what are the known benefits and related risks?
A 2016 Cochrane review of 37 randomized trials (4,023 women) compared TVM with NTR. Three primary outcomes were defined: awareness of prolapse, recurrence, and repeat surgery. Compared with women treated with NTR, those treated with synthetic non-absorbable TVM exhibited a greater reduction in awareness of prolapse (risk ratio [RR], 0.66; 95% confidence interval [CI], 0.54–0.81), decreased recurrence in the anterior compartment (RR, 0.33; 95% CI, 0.26–0.40), and decreased reoperation for prolapse (RR, 0.53; 95% CI, 0.31–0.88). The overall calculated exposure rate was 12%, with a very wide range of 3.2% to 20.8%. This wide range is not doubt attributed to a suboptimal, split-thickness dissection. There were no differences in other key secondary outcomes, including dyspareunia, operating time, and estimated blood loss. A study of 5-year follow-up after TVM placement, reported that patients had continued significant improvements in both subjective and objective outcomes. A 10-year observational study demonstrated a recurrence rate of only 2.6% in the anterior compartment.
How does TVM compare with sacrocolpopexy?
Our experience has been that TVM yields similar outcomes to sacrocolpopexy with additional benefits. We completed a 1-year retrospective cohort study comparing robot-assisted laparoscopic sacrocolpopexy (RALS) with TVM in 86 patients. Both treatment groups showed statistically significant improvements in nearly all functional and quality-of-life measures, including urinary symptoms, sexual function, and POP-Q scores. In particular, points Aa and Ba on the POP-Q score were significantly improved with TVM as compared to RALS. This suggests that TVM can achieve both lateral and apical support, where sacrocolpopexy mostly addresses only the apex. This correlate with DeLancey’s dynamic magnetic resonance imaging studies, which demonstrate advanced prolapse results from both apical and lateral detachment. TVM placement also was considerably faster than RALS by approximately 96 minutes and performed under regional anesthesia.
What about concerns of exposure with TVM?
To minimize the risk of mesh exposure, the surgeon must properly dissect into, and develop the true pelvic “spaces” between the bladder above (vesico-vaginal) and the rectum below the vagina (recto-vaginal). This requires a “full thickness” dissection of the vaginal wall. The proper technique is first precise hydro dissection of these true pelvic spaces followed by sharp, then blunt dissection. This full-thickness dissection technique is relatively easy to teach surgeons who have appropriate background training in pelvic surgery.
Mesh exposure is a well described and an accepted complication of an abdominal sacral-colpopexy (ASC). The 2003 Colpopexy and Urinary Reduction Efforts (CARE) trial, the exposure rate was 6.4%. A 2013 study of seven years follow-up from the same CARE trial revealed the risk of mesh exposure to rise to 10.5% (95% C.I, 6.8%-16.1%). This exposure risk is very similar, and in some reports higher than TVM. When looking at a large, multicenter trial of TVM with over 400 patients conducted by surgeons who perform the index surgery on a regular basis, the risk of exposure requiring a procedure to correct it was only 3.2%.
Other studies have reported the exposure rate after TVM placement to be higher than that reported in ASC. This is no doubt directly related to the technical challenge of achieving placement of the mesh material deep or “behind” all of the histological layers comprising the vaginal wall. If during a TVM procedure, the surgeon uses a “splitting” dissection technique (dividing the vaginal wall between the mucosa and muscularis), instead of achieving a full thickness vaginal wall dissection into the true vesicovaginal space, the exposure rate will undoubtedly be higher than that seen after ASC, as any TVM placed “in” the vaginal wall rather than deep “behind” it is more likely to become exposed.
Studies on TVM have shown that low-volume surgeons have significantly higher reoperation rates often to correct exposure, while high-volume surgeons achieved a 41% reduction in such reoperations. With standardization of the dissection component (which is very achievable), the rate of mesh exposure undoubtedly will dramatically decrease.
What about concerns of dyspareunia with TVM?
In a review of seven RCTs of TVM versus NTR, one study showed worse pain in the non-mesh repair, and the other six studies showed no difference in sexual function. In 2008, Lowman et al. specifically examined the concern that TVM may cause higher rates of dyspareunia than other surgeries. The reported rate in this study of de novo dyspareunia was less than that of similar vaginal approaches using NTR, and only slightly higher than ASC. As mentioned, the 2016 Cochrane review of 37 RCTs demonstrated no difference in dyspareunia rates among patients who received TVM in the anterior compartments versus NTR for treatment of cystocele.
Who should ensure surgeons have the proper skill set to perform procedures?
When considering the question of who should be training and certifying physicians on new innovative procedures, it is clear that it never has been, nor should it ever be, the primary responsibility of industry. Medical device companies are very willing, if not eager, to help support the educational process in surgeon skill development. The multiple educational opportunities afforded to the physician community by industry cannot, nor should they, substitute for the hospitals’ responsibility of defining the longitudinal process of physician credentialing and the final approval of granting operative privileges to the surgeon.
In summary, given the trend of increasing longevity with women living longer than ever before, and engaging in a more active lifestyle, reconstructive pelvic surgery utilizing only suture based NTR is unlikely to provide a durable effective result for correction of POP involving the anterior compartment. There are also established clinical risk factors for recurrences which we can screen for in these patients to shape our decision making to utilize mesh augmentation. It is therefore imperative that; we as the medical community caring for women with POP, continue to have TVM as part of our surgical options in designing individual surgical care for each and every unique patient. As we evaluate the risk of TVM, by reviewing the evidence based medicine available, we must realize the critical role of the implanting surgeon skill has not been accounted for in the clinical trials to date. The most recent extensive review of published evidence to date, the 2016 Cochrane review, demonstrated that TVM in the anterior compartment for the treatment of cystocele when compared to native tissue repair resulted in: … “lower rates of awareness of prolapse …, lower rates of repeat surgery for prolapse …, and the finding of prolapse on exam …” Although the report did state TVM had a higher repeat surgery for what was defined as a “composite outcome” for any of the following: recurrent prolapse, postoperative stress incontinence development, and lastly exposure, the overwhelming majority of these “repeat surgeries” were due to exposure which is clearly a surgeon factor, and can be significantly reduced through better surgeon training.
TVM repair in the anterior compartment needs to remain available as a treatment option for all the women in our communities now and in the future, who will suffer from POP, they all deserve a safe and durable surgical correction.