Multicenter trial to evaluate single-incision slings

In this interview, Catherine Ann Matthews, MD, FACS, FACOG, discusses the resurgence of single-incision slings and outlines a clinical trial of slings that she is currently leading. Matthews is the division head and fellowship director of urogynecology at Wake Forest Baptist Health in Winston-Salem, North Carolina. She was interviewed by Gopal H. Badlani, MD, co–editor in chief of Urology Times® and professor and vice chair of urology at Wake Forest University.

Dr. Badlani: The midurethral sling basically revolutionized the management of stress incontinence. Did you adopt it early in your practice?

Dr. Matthews: Interestingly, I did not. I was very skeptical about the blind introduction of mesh into the pelvis, so I was not an early adopter. It was only after the randomized trial that Paul Hilton [, MD, BS, MRCOG], conducted in the [United Kingdom that compared] slings [with] Burch procedures—which demonstrated equivalence and even superiority in intraoperative outcomes—that I felt confident and comfortable to introduce them into my practice.

Why do you think urogynecologists favored transobturator tape (TOT) vs midurethral slings/transvaginal tape?

I’m not sure I agree that all urogynecologists preferred TOT. I think it’s true that people who are not subspecialized in urogynecology felt it was much safer to avoid the retropubic space. There is no question that the rare cases of bleeding, bladder perforation, and very rare cases of bowel injury are all avoided in the transobturator sling technique. As a consequence, I think generalists felt a lot more comfortable doing that sling. I, again, was reticent about full-length TOTs, despite the [Trial of Mid-Urethral Slings (NCT00325039)] data, because of occasionally seeing a woman with very severe thigh and groin pain. I was also concerned I wasn’t technically competent at fishing out slings from the inner thigh. I was nervous about putting something in I didn’t have full confidence in my competence at getting out.

Then the single-incision sling came along, but its initial iteration sort of faded away. Why is it seeing a resurgence?

I appreciate people’s desire to continue to innovate and improve on what currently exists. I think people recognized that passing the sling all the way through the muscles of the inner thigh was maybe associated with more pain than was necessary. Most unfortunately, the very first iteration of a single-incision sling had this terrible design, where it was attached behind the symphysis. The TVT-Secur was a tragic operation that put minislings behind in terms of innovation adoption. A lot of the subsequent meta-analyses of single-incision slings continued to incorporate the TVT-Secur data, despite the improvement in the outcomes people were seeing with the MiniArc, because that was the next minisling that was introduced. People quickly recognized the TVT-Secur device was a bad design. Then when people started adopting the bullet technique of anchoring things into the obturator internus muscle, we started seeing fewer complications and better outcomes—certainly outcomes that seemingly were in line with the full-length TOT slings.

How does the single-incision sling work in terms of correcting stress incontinence?

It works the same way as the full-length TOT sling. We have seen, with ultrasound, the ability of these slings to effectively kink the urethra, so they all rely on mobility of the urethra. The same mechanism is holding true that you’ve got this seatbelt, bandlike substance that the urethra is physically compressed against, with increased intra-abdominal pressure. Because the anchors in the obturator internus muscle are providing stability of that seatbelt support, the urethra is effectively compressed against it during episodes of increased intra-abdominal pressure.

Please discuss the multicenter trial of single-incision slings that you are leading.

The trial you’re referring to is called the ALTIS [522] study [NCT02348112]. It is a randomized trial of women who are undergoing native tissue vaginal repair for multicompartment prolapse repair. Our question was: Is it noninferior to use a single-incision sling in this patient population for both symptomatic and occult stress incontinence with reduction of prolapse? We thought [that] in these patients who are not primarily coming for treatment of just stress incontinence but are coming primarily for the management of prolapse, we needed to see whether a single-incision sling was equivalent to a retropubic sling. We all know single-incision slings have fewer intraoperative complications, potentially, than a retropubic sling. So in this population that wasn’t coming primarily for stress incontinence, we thought it was a good population to determine [whether] there was equipoise with the lower-risk device.

We’re at 80% recruitment, so we’re almost finished with enrollment. We haven’t yet published the results. In this study, we’re using [an adjustable] sling from Coloplast[Altis], which gives us the opportunity intraoperatively to adjust the tension of the sling. Of course, the other single-incision sling available is the nonadjustable Solyx sling, and we’re doing another randomized trial of that sling in patients undergoing sacrocolpopexy. [Hopefully I] will have more information about the results [soon], but I will tell you that on preliminary analysis, we haven’t seen significantly different results in 1 group vs the other. I suspect our findings on this prolapse cohort will likely be very similar to the randomized trial that was just published in the New England Journal of Medicine comparing single-incision slings to retropubic slings from the UK.1 I suspect we’ll find that they’re noninferior in this population, as well.

How long do you think it should be before we call single-incision slings the standard of care?

That’s a very fair question. To be completely honest, if we have 5 years of outcomes data that demonstrate no significant decline in efficacy, then one would assume we’re not going to see radically different results at 10, 15, and 20 years—very similar to the initial collection of the retropubic data. In my practice, I’d be willing to substitute a single-incision sling for the gold-standard retropubic if there are equivalent outcomes at 5 years post procedure. I think it’s interesting that the single-incision sling trial in the UK found that there was equipoise between the 2 slings at 3 years, and we saw greater satisfaction for the single-incision sling group. It’s interesting that for a long time, we’ve held on to the potentially more dangerous retropubic sling with the belief there was some superiority, particularly in women with lower-pressure urethras. But I think the technology for single-incision slings has advanced, and we are now at [a] place where you probably will be able to substitute one for the other.

Between a single-incision and retropubic slings, do you think there will still be a place for TOT?

I think TOT is done. It seems like there is no further reason to pass a sling all the way through the muscles of the inner thigh. It seemed to be that was the cause of pain, and if you stop at the obturator internus membrane and muscle, it seems [that] most of that pain is avoided. It’s not 0, and it’s important to note that was the 1 thing that was increased in that randomized trial published in the New England Journal of Medicine. We haven’t eradicated pain. For populations, [such as] horse riders and cyclists—people [who] are doing lots of sports activities, where the muscles of the inner thigh may be involved—I still would prefer to use a retropubic sling. This is where becoming nuanced in your approach to stress incontinence as opposed to “1-sling-fits-all” is appropriate. For all those patients with voiding dysfunction, Valsalva voiding, and people with prior abdominal surgeries—these are people one wants to avoid the retropubic space. In those populations, for sure, single-incision slings would be a preferred alternative.

The technique for placing the single-incision sling is slightly different than the retropubic. How is the learning curve? What do you teach differently about these?

That is [a] fundamental and supremely important point to be made. These slings are far more nuanced than the retropubic sling. The Retropubic sling is designed to be tension free in pretty much every patient, and your risk in that sling was that you might just put it in too tight. In the single-incision slings, the adjustable sling from Coloplastis technically a lot easier for surgeons to learn. Still, that sling needs to be “kissing,” right up against the urethra. The Solyx sling is more nuanced and more challenging to initially learn. However, I feel like the mesh material is perhaps lower risk for exposure, but there’s no question that there are more nuances in the hand motions. It is very reproducible once you learn those hand motions, but I would caution anyone, even someone who’s very well trained, to spend time on a cadaver and pelvic model to really learn the nuanced hand motions and recognize these slings all are placed tighter than retropubic and transobturator slings. They really are abutting the urethra. One needs to be able to clearly pass a clamp behind the sling and not have the sling be bending or in any way getting smaller where it lays across the urethra. Just like a seatbelt sits on you, it’s touching your body, it’s giving you some contact—that’s the way the single-incision slings need to be placed.

Speaking of mesh, how do you explain the divergence in opinion based on its use? It’s good for the sling, robotic, and laparoscopic placement, but it’s considered bad when placed vaginally.

That’s a good question. I believe that with polypropylene mesh, the amount of mesh, the way it’s anchored, and how it is put in makes a big difference in outcomes. I make this analogy to patients: Sugar makes you fat. Well, there is truth to that statement, but a small amount of sugar [that is] taken in the right way doesn’t make you fat. [However], a lot of sugar used indiscriminately can have bad consequences. It’s very similar with pelvic mesh. If we look at the load, the amount of mesh used in the sling is relatively small compared [with] the amount of mesh used, for example, in a multicompartment vaginal prolapse repair, like PROlift.

How one anchors it also makes a big difference. If mesh is anchored in multiple different places and there’s tension on that mesh, it doesn’t behave very well. There are 2 points of fixation with a single-incision sling, [and] there are no points of actual suturing or fixation with a retropubic sling, [which] then causes a difference in behavior.

Finally, there is how we put it in. Slings are placed through a 1-cm incision. There is no vaginal mesh for prolapse repair that can be put in through a 1-cm incision. Of course, with mesh we put in with sacrocolpopexy, there should be no vaginal incisions; it’s all done from the inside. I think not making vaginal incisions very much affects the subsequent behavior of the mesh on the other side.

Where do you see the ideal case for single incision vs retropubic in the future?

Retropubic slings are going to be a better alternative for patients with a more fixed urethra, a low-pressure urethra, where you need some good interaction between the sling and the anterior abdominal wall. Single-incision slings are great alternatives for women with hypermobile urethras and are preferred in those with preexisting voiding dysfunction or lower-pressure bladders. If they’re doing any Valsalva-assisted voiding, we know the retropubic slings will engage with the anterior abdominal wall when they’re Valsalva voiding, and they’re going to cause obstruction. I’ve not observed that same phenomenon when [placing] a single-incision sling. I also would prefer to use a single-incision sling in a patient with a higher risk of bleeding, for example a Jehovah’s Witness—I don’t see any place in the future for going into the retropubic space and causing an increased risk of bleeding And certainly, [for] people with a history of bowel surgery, there’s absolutely no reason to forego a single-incision sling.

Is there anything else you would like to add?

It’s very exciting that the data from the UK are so positive. I hope their governing bodies will look at those results and recognize that very meticulous data were collected. There were no patients with catastrophic outcomes. Some great research has been done in this space, and I hope we will continue to do good science to understand outcomes and that we’ll still have the ability in the future to use mesh slings—both retropubic and single-incision—for stress incontinence.


1. Abdel-Fattah M, Cooper D, Davidson T, et al. Single-incision mini-slings for stress urinary incontinence in women. N Engl J Med.2022;386(13):1230-1243. doi:10.1056/NEJMoa2111815