Minimally invasive synthetic midurethral slings may be considered the standard of care for the surgical treatment of stress urinary incontinence – and a first-line treatment for severe cases of the condition – based on the publication of numerous level 1 randomized trials, high-quality reviews, and recent position statements from professional societies.
The current evidence base shows that midurethral sling operations are as effective as bladder neck slings and colposuspension, with less morbidity. Operating times are shorter, and local anesthesia is possible. Compared with pubovaginal slings, which are fixed at the bladder neck, midurethral slings are associated with less postoperative voiding dysfunction and fewer de novo urgency symptoms.
Midurethral slings (MUS) also have been shown to be more successful – and more cost-effective – than pelvic floor physiotherapy for stress urinary incontinence (SUI) overall, with the possible exception of mild SUI.
Physiotherapy involving pelvic floor muscle therapy has long been advocated as a first-line treatment for SUI, with MUS surgery often recommended when physiotherapy is unsuccessful. In recent years, however, with high success rates for MUS, the role of physiotherapy as a first-line treatment has become more debatable.
A multicenter randomized trial in 660 women published last year in the New England Journal of Medicine substantiated what many of us have seen in our practices and in other published studies: significantly lower rates of improvement and cure with initial physiotherapy than with primary surgery.
Initial MUS surgery resulted in higher rates of subjective improvement, compared with initial physiotherapy (91% vs. 64%), subjective cure (85% v. 53%), and objective cure (77% v. 59%) at 1 year. Moreover, a significant number of women – 49% – chose to abandon conservative therapy and have MUS surgery for their SUI during the study period (N. Engl. J. Med. 2013;369:1124-33).
A joint position statement published in early 2014 by the American Urogynecologic Society (AUGS) and the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) calls MUS the most extensively studied anti-incontinence procedure and “probably the most important advancement in the treatment of SUI in the last 50 years.” More than 2,000 publications in the literature have described the procedure for SUI, and multiple randomized controlled trials have compared various types of MUS procedures as well as MUS to other nonmesh SUI procedures, the statement says.
My colleague and I recently modeled the cost-effectiveness of pelvic floor muscle therapy and continence pessaries vs. surgical treatment with MUS for initial treatment of SUI. Initial treatment with MUS was the best strategy, with an incremental cost-effectiveness ratio of $32,132 per quality-adjusted life-year, compared with initial treatment with pelvic floor muscle therapy. Under our model, treatment with a continence pessary would never be the preferred choice due to low subjective cure rates (Am. J. Obstet. Gynecol. 2014;211:565.e1-6).
I now tell patients who present with a history of severe stress incontinence, and who leak on a cough stress test, that a trial of pelvic floor physiotherapy is an option but one with a lower likelihood of success. I recommend an MUS as primary treatment for these patients, and the question then often becomes which sling to use.
There are two broad approaches to MUS surgery – retropubic and transobturator – and within each approach, there are different routes for the delivery of the polypropylene mesh sling.
Retropubic slings. Retropubic slings are passed transvaginally at the midurethral level through the retropubic space. Tension-free vaginal tape (TVT) has been used in millions of women worldwide, with good long-term outcomes, since it was introduced by Dr. Ulf Ulmsten in 1995. The TVT procedure utilizes a bottom-up approach, with curved needles being passed from a small vaginal incision up through the retropubic space to exit through two suprapubic incisions.
A second type of retropubic sling – the suprapubic urethral support sling (SPARC, American Medical Systems) – utilizes a downward-pass, or top-down, approach in which a metal trocar is passed through suprapubic incisions and down through the retropubic space to exit a vaginal incision.
The theoretical advantages of this modification to the TVT procedure have included more control over the needle introducer near the rectus fascia, and a lower risk of bowel and vascular injury. However, comparisons during the last decade of the two retropubic approaches have suggested slightly better outcomes – relating both to cure rates and to complication rates – with TVT compared with SPARC.
A Cochrane Review published in 2009, titled “Minimally invasive synthetic suburethral sling operations for stress urinary incontinence in women,” provided higher-level evidence in favor of bottom-up slings. A sub-meta-analysis of five randomized controlled trials – part of a broader intervention review – showed that a retropubic bottom-up approach was more effective than a top-down route (risk ratio, 1.10), with higher subjective and objective SUI cure rates (Cochrane Database Syst. Rev. 2009(4): CD006375). There also was significantly less bladder perforation, less mesh erosion, and less voiding dysfunction.