Introduction

In the surgical treatment of stress urinary incontinence (SUI), there are multiple sling types and techniques available. As a result, the choices for patients and their surgeons can be both challenging and confusing. Fortunately, at this year’s AUA Annual Meeting, a panel of experts will help sort out which type of sling is best for the index patient defined as “an otherwise healthy female who is considering surgical therapy for the correction of pure stress and/or stress-predominant mixed urinary incontinence who has not undergone previous SUI surgery.”¹ Dr Michael Albo will argue in favor of the retropubic midurethral sling (MUS). Dr Eric Rovner stands by the autologous pubovaginal fascial sling (aPVS), and Dr Suzette Sutherland defends the newer single-incision sling (SIS). Which type is best? Read on for a preview of the “great sling debate.”

Michael Albo, MD: Retropubic MUS

Since its introduction in the 1990s, the standard retropubic MUS has become the dominant procedure for the treatment of stress incontinence, and for good reason. It is a highly effective, durable, minimally invasive, and safe procedure. The technique is well described and can be standardized across patients and surgeons, which contributes to predictable and reproducible outcomes.

Numerous clinical trials and meta-analyses have consistently demonstrated the efficacy, durability, and safety of the standard MUS, and no procedure has demonstrated superior cure or improvement rates.² These studies have also shown long-term durability, with sustained efficacy and low rates of recurrence over extended follow-up.³ Furthermore, reoperation rates are lower than with both single-incision and pubovaginal slings. The most recent Cochrane review of traditional suburethral slings identified only 14 comparative studies and concluded that they are probably no better, and may be less effective, than the MUS in terms of number of women continent in the medium term (1-5 years).⁴ In addition, the MUS is clearly less invasive and has fewer complications.

There have been persistent efforts to minimize the adverse events associated with the standard MUS. The transobturator technique was developed to avoid the retropubic space, while the SIS was developed using a smaller volume of mesh and avoiding the pain associated with passing the trocar near the adductor longus tendon. While these techniques have demonstrated noninferiority to the standard retropubic MUS in regard to efficacy, they have not definitively established that they are safer or preferred by patients.

Indeed, the most recent Cochrane review of the SIS concluded that it remained uncertain whether the SIS offered lower rates of postoperative retention, repeat continence surgery, or surgery for mesh revision. In addition, it remained unclear if the single incisions led to higher rates of mesh exposure, extrusion, or erosion compared with retropubic MUS. There are still uncertainties regarding adverse events and longer-term outcomes. Therefore, longer-term data are needed to clarify the safety and long-term effectiveness of SIS compared to other midurethral slings.⁵

We have learned that cure or improvement of stress incontinence is not the only outcome that matters to our patients. Preferences regarding the risk and type of adverse events, invasiveness, length of recovery, durability of the procedure, and whether or not mesh is used are significant variables that must be considered. However, for the majority of my patients, the standard retropubic MUS is the procedure of choice.

Eric Rovner, MD: aPVS

It is generally agreed that no single procedure or intervention is optimal for all female patients with SUI. However, the aPVS is the gold standard and clearly the best choice. It is the predicate sling procedure upon which all subsequent slings are compared. Dozens of sling types and techniques have been introduced as alternatives to the aPVS over the last 140 years in order to shorten operative time; minimize intraoperative and postoperative recovery, pain, and convalescence; and/or reduce the cost or morbidity of female SUI surgery. The vast majority of these have failed in the short or long term due to unforeseen morbidity, complications, or lack of durability, and have been consigned to the dustbin of surgical history. And although some of the remaining contemporary sling interventions may improve on one or more aspects as compared to the aPVS, none have yet been demonstrated to be superior to the aPVS for the treatment of female SUI.

The “index patient” as defined by the AUA¹ is somewhat limiting as it applies to only “virgin” SUI patients. However, the aPVS has been, and continues to be, the “go-to” procedure for both virgin⁶ and complex patients with prior failed surgeries, with or without intrinsic sphincter deficiency, with or without urethral hypermobility, and with or without prior urethral surgery (fistula, urethral diverticula, etc).⁶ Unlike the aPVS, mesh slings of any type are not often considered the first choice for redo cases of complex recurrent female SUI. Thus, it is not unreasonable to argue that the recognized gold standard for SUI, the aPVS, which is clearly effective as a salvage procedure for prior failed mesh slings,^7,8 should be also used for virgin patients as well.

Many procedures have been abandoned for the surgical treatment of female SUI over the years, and it is possible that several of the contemporary mesh sling procedures may, over time, have the same fate. Nevertheless, the aPVS remains the only procedure to be recognized and approved by all 7 iterations of the International Consultation on Incontinence⁹ and all editions and updates to the AUA guideline on the surgical management of female stress urinary incontinence.¹

Suzette Sutherland, MD: SIS

The mesh MUS is well established as a safe and efficacious treatment option for women with SUI, especially the index case associated with urethral hypermobility. To date, it is the most studied and most performed anti-incontinence procedure globally. Prior to the development of the MUS in the mid- to late-1990s, the aPVS was considered the “gold standard” for the surgical treatment of SUI due to both urethral hypermobility and intrinsic sphincter deficiency.¹⁰ However, with the addition of the MUS to the surgical armamentarium, that position has been challenged. Although a recent meta-analysis involving almost 16,000 patients noted similar efficacy between MUS and aPVS at 5 years, longer-term (> 5 year) comparative data are still lacking. And when evaluating both efficacy and safety, the superiority of the MUS was confirmed.¹¹

The mechanism of action of the MUS is based on the “Integral Theory” by Petros and Ulmsten (1990), which describes dynamic kinking of the midurethra by the pubourethral ligament during valsalva. Accordingly, this type of sling was designed as a tension-free procedure for women with SUI due to urethral hypermobility.¹² With advancing innovation over the ensuing decades, the MUS procedure and mesh sling devices have evolved with the intent of providing improved surgical safety while maintaining the same excellent efficacy. This led to the introduction and Food and Drug Administration approval of the retropubic transvaginal tape (TVT; 1996), transobturator tape (TOT; 2003), and the SIS (2008).

Previous concerns about “immature dates” pertaining to the long-term efficacy of the SIS¹³ are now no longer valid. Today, 15 years after the introduction of the SIS to the US market, sufficient data with level I evidence notes equal, noninferior efficacy compared to TVT and TOT in the index patient with no deterioration over time (comparing 2 to 10 years—with objective and subjective cure rate percentiles repeatedly in the high 80s).¹⁴ And, as reported in a very recent 2023 Cochrane review, SIS “may be as effective as retropubic slings” and “are as effective as transobturator slings.”⁵ Although the TVT is noted to have slightly enhanced cure durability, this comes at the cost of higher intraoperative complications and postoperative voiding dysfunction.¹¹ Although rare, devastating and even life-threatening complications within the retropubic space and transobturator/thigh space have occurred. This provided the inspiration for further MUS innovation; and thus, the SIS was born.

By eliminating the need to enter either the retropubic or transobturator/thigh spaces, the SIS provides a safer option for MUS delivery. Indeed, the advantages of the SIS are mainly related to improved safety features including minimal mesh burden; limited surgical dissection; shorter blind trocar passages; reduced potential for surrounding organ perforation, occult bleeding, or hematoma formation; and a more secure anchoring mechanism with earlier return to daily activities. When evaluating other mesh-related complications with the MUSs, the most common—mesh extrusion into the vagina—is exceedingly rare (3%-5%) in trained hands and readily managed, as noted by contemporary data, regardless of the mode of MUS delivery. Although postoperative urinary retention, obstructive voiding symptoms, and/or de novo voiding dysfunction with urgency are possible with any type of anti-incontinence procedure, the incidence associated with aPVS is highest (22%-30%), followed by the TVT, the TOT, and then the SIS. With these advances and the subsequent long-term efficacy data now available, the AUA/SUFU (Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction) guidelines 2023 update for the surgical treatment for female SUI now acknowledges the SIS as an equally viable option for the surgical treatment of SUI in the index patient.¹