Midurethral slings

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.

Sling selection

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.

TVT slings, therefore, appear to be somewhat superior, with statistically significant differences in each of the domains of efficacy and morbidity. Still, surgeon experience and skill remain factors in sling selection; the surgeon who feels comfortable and skilled with a top-down approach and has little experience with a bottom-up approach should continue with SPARC. For surgeons who are skilled with both approaches, it might well be preferable to favor TVT.

Transobturator slings. The transobturator approach was developed to minimize the potential for bladder and bowel injuries by avoiding the pelvic organs in the retropubic space. The sling is introduced either through an inside-out technique, with the needle passed from a vaginal incision and out through the obturator foramen, or through an outside-in technique, with the needle passed through the thigh and then out through the vaginal incision.

A meta-analysis of trials of transobturator sling procedures – including four direct-comparison, randomized controlled trials of the inside-out technique vs. the outside-in technique – showed no significant differences between the two approaches in subjective and objective SUI cure rates in the short term. Rates of postoperative voiding difficulties and de novo urgency symptoms were similar (BJU Int. 2010;106:68-76).

Making a choice. Each of the currently available midurethral slings appears to work well, overall, with few clinically significant differences in outcomes. On the other hand, midurethral slings are not all the same. It is important to appreciate the more subtle differences, to be aware of the evidence, and to be appropriately trained. Often, sling selection involves weighing the risks and benefits for the individual.

On a broad scale, the most recent high-level comparison of the retropubic and transobturator slings appears to be a meta-analysis in which retropubic midurethral slings showed better objective and subjective cure rates than transobturator midurethral slings. Women treated with retropubic slings had a 35% higher odds of objective cure and a 24% higher odds of subjective cure. (The weighted average objective cure rates were 87% for retropubic slings vs. 83% for transobturator slings with a weighted average follow-up of approximately 17 months. The weighted average subjective cure rates were 76% and 73%, respectively.)

Operating times were longer with retropubic slings, but lengths of stay were equivalent between the two types of procedures. This was based on 17 studies of about 3,000 women (J. Urology 2014 [doi: 10.1016/j.juro.2014.09.104]).

The types of complications seen with each approach differed. Bladder perforation was significantly more common with retropubic slings (3.2% vs. 0.2%), as was bleeding (3.2% v. 1.1%). Transobturator slings were associated with more cases of neurologic symptoms (9.4% v. 3.5%) and vaginal perforation (3.6% v. 0.9%).

This new review provides updated information to the 2009 Cochrane Review mentioned above, which reported that women were less likely to be continent after operations performed via the obturator route, but also less likely to have encountered complications. More specifically, objective cure rates were slightly higher with retropubic slings than with transobturator slings (88% vs. 84%) in the 2009 review. There was no difference in subjective cure rates. With the obturator route, there was less voiding dysfunction, blood loss, and bladder perforation (0.3% v. 5.5%).

Other pivotal trials since the 2009 Cochrane Review include a multicenter randomized equivalence trial published in the New England Journal of Medicine in 2010. The trial randomized 597 women to transobturator or retropubic sling surgery, and found no significant differences in subjective success (56% vs. 62%) or in objective success (78% vs. 81%) at 12 months (N. Engl. J. Med. 2010;362:2066-76).

There is some level 1 evidence suggesting that for severe incontinence involving intrinsic sphincter deficiency (ISD), a retropubic TVT sling is the more effective procedure. A randomized trial of 164 women with urodynamic SUI and ISD, for instance, found that 21% of those in the TVT group and 45% of those in the transobturator group had urodynamic SUI 6 months postoperatively.

The risk ratio of repeat surgery was 2.6 times higher in the transobturator group than in the retropubic TVT group (Obstet. Gynecol. 2008;112:1253-61). TVT was more effective both with and without concurrent pelvic organ prolapse repair.

I tell my patients with severe SUI or ISD, therefore, that retropubic sling procedures appear to be preferable. (Exceptions include the patient who has a history of retropubic surgeries, in whom passing the sling through this route may not be the safest approach, as well as the patient who has had mesh erosion into the bladder.)

In patients whose SUI is less severe, I counsel that a transobturator sling confers satisfaction rates similar to those of a retropubic sling and has a lower risk of complications, such as postoperative voiding dysfunction and bladder perforations, but with the possible trade-off of more thigh discomfort. I also might recommend a transobturator sling to patients with more pronounced initial complaints of urinary urgency and frequency, and to patients who have minor voiding dysfunction or a low level of incomplete bladder emptying.

While often short-lived, the small risk of thigh pain with a transobturator sling makes me less likely to recommend this type of sling for a woman who is a marathon runner or competitive athlete. In her case, an analysis of possible complications includes the consideration that bladder perforation can be addressed relatively quickly in the operating room, while persistent thigh discomfort, though relatively rare, could be a debilitating problem.

Single-incision slings

There appears to be emerging evidence suggesting that some of the fixed and adjustable single-incision slings currently available may have efficacy similar to that of the slings that are now widely used.

A Cochrane Review presented at the 2014 AUGS-IUGA scientific meeting and published this summer concludes that there is not enough evidence on single-incision slings compared with retropubic or transobturator slings to allow reliable comparisons, and that additional, adequately powered, high-quality trials with longer-term follow-up are needed (Cochrane Database Sys. Rev. 2014;6:CD008709). However, research completed since the review offers additional data.

For instance, at the 2014 AUGS-IUGA scientific meeting this summer, an oral paper presentation highlighted findings of a randomized controlled trial that showed similar cure rates after surgery with the MiniArc, a fixed single-incision sling, and the Monarc transobturator sling (both by American Medical Systems) at 24 months. The study randomized 234 women to either sling and found no significant differences in subjective outcomes, objective outcomes, or results on various quality-of-life questionnaires.

As such studies are published and more evidence emerges, we will gain a clearer picture of how the newer single-incision slings compare to the well-tested retropubic and transobturator slings with respect to efficacy and safety.

Single-incision slings require only a small vaginal incision and no exit points. Without abdominal or thigh incisions, these new procedures – intended for less severe SUI (no ISD) – may offer improved perioperative and postoperative patient comfort and a potentially decreased risk of surgical injury to the adductor muscles, as well as a decreased risk of vascular and nerve injury. Candidates for these slings may include those who are very athletic, those who are obese, and those with a history of prior retropubic or pelvic surgery.

Research appears to be progressing, but at this time we do not yet have level 1 evidence to support their routine use.

Dr. Sokol reported that he owns stock in Pelvalon, and is a clinical adviser to that company. He also is a national principal investigator for American Medical Systems, and the recipient of research grants from Acell and several other companies.

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.

Sling selection

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.

TVT slings, therefore, appear to be somewhat superior, with statistically significant differences in each of the domains of efficacy and morbidity. Still, surgeon experience and skill remain factors in sling selection; the surgeon who feels comfortable and skilled with a top-down approach and has little experience with a bottom-up approach should continue with SPARC. For surgeons who are skilled with both approaches, it might well be preferable to favor TVT.

Transobturator slings. The transobturator approach was developed to minimize the potential for bladder and bowel injuries by avoiding the pelvic organs in the retropubic space. The sling is introduced either through an inside-out technique, with the needle passed from a vaginal incision and out through the obturator foramen, or through an outside-in technique, with the needle passed through the thigh and then out through the vaginal incision.

A meta-analysis of trials of transobturator sling procedures – including four direct-comparison, randomized controlled trials of the inside-out technique vs. the outside-in technique – showed no significant differences between the two approaches in subjective and objective SUI cure rates in the short term. Rates of postoperative voiding difficulties and de novo urgency symptoms were similar (BJU Int. 2010;106:68-76).

Making a choice. Each of the currently available midurethral slings appears to work well, overall, with few clinically significant differences in outcomes. On the other hand, midurethral slings are not all the same. It is important to appreciate the more subtle differences, to be aware of the evidence, and to be appropriately trained. Often, sling selection involves weighing the risks and benefits for the individual.

On a broad scale, the most recent high-level comparison of the retropubic and transobturator slings appears to be a meta-analysis in which retropubic midurethral slings showed better objective and subjective cure rates than transobturator midurethral slings. Women treated with retropubic slings had a 35% higher odds of objective cure and a 24% higher odds of subjective cure. (The weighted average objective cure rates were 87% for retropubic slings vs. 83% for transobturator slings with a weighted average follow-up of approximately 17 months. The weighted average subjective cure rates were 76% and 73%, respectively.)

Operating times were longer with retropubic slings, but lengths of stay were equivalent between the two types of procedures. This was based on 17 studies of about 3,000 women (J. Urology 2014 [doi: 10.1016/j.juro.2014.09.104]).

The types of complications seen with each approach differed. Bladder perforation was significantly more common with retropubic slings (3.2% vs. 0.2%), as was bleeding (3.2% v. 1.1%). Transobturator slings were associated with more cases of neurologic symptoms (9.4% v. 3.5%) and vaginal perforation (3.6% v. 0.9%).

This new review provides updated information to the 2009 Cochrane Review mentioned above, which reported that women were less likely to be continent after operations performed via the obturator route, but also less likely to have encountered complications. More specifically, objective cure rates were slightly higher with retropubic slings than with transobturator slings (88% vs. 84%) in the 2009 review. There was no difference in subjective cure rates. With the obturator route, there was less voiding dysfunction, blood loss, and bladder perforation (0.3% v. 5.5%).

Other pivotal trials since the 2009 Cochrane Review include a multicenter randomized equivalence trial published in the New England Journal of Medicine in 2010. The trial randomized 597 women to transobturator or retropubic sling surgery, and found no significant differences in subjective success (56% vs. 62%) or in objective success (78% vs. 81%) at 12 months (N. Engl. J. Med. 2010;362:2066-76).

There is some level 1 evidence suggesting that for severe incontinence involving intrinsic sphincter deficiency (ISD), a retropubic TVT sling is the more effective procedure. A randomized trial of 164 women with urodynamic SUI and ISD, for instance, found that 21% of those in the TVT group and 45% of those in the transobturator group had urodynamic SUI 6 months postoperatively.

The risk ratio of repeat surgery was 2.6 times higher in the transobturator group than in the retropubic TVT group (Obstet. Gynecol. 2008;112:1253-61). TVT was more effective both with and without concurrent pelvic organ prolapse repair.

I tell my patients with severe SUI or ISD, therefore, that retropubic sling procedures appear to be preferable. (Exceptions include the patient who has a history of retropubic surgeries, in whom passing the sling through this route may not be the safest approach, as well as the patient who has had mesh erosion into the bladder.)

In patients whose SUI is less severe, I counsel that a transobturator sling confers satisfaction rates similar to those of a retropubic sling and has a lower risk of complications, such as postoperative voiding dysfunction and bladder perforations, but with the possible trade-off of more thigh discomfort. I also might recommend a transobturator sling to patients with more pronounced initial complaints of urinary urgency and frequency, and to patients who have minor voiding dysfunction or a low level of incomplete bladder emptying.

While often short-lived, the small risk of thigh pain with a transobturator sling makes me less likely to recommend this type of sling for a woman who is a marathon runner or competitive athlete. In her case, an analysis of possible complications includes the consideration that bladder perforation can be addressed relatively quickly in the operating room, while persistent thigh discomfort, though relatively rare, could be a debilitating problem.

Single-incision slings

There appears to be emerging evidence suggesting that some of the fixed and adjustable single-incision slings currently available may have efficacy similar to that of the slings that are now widely used.

A Cochrane Review presented at the 2014 AUGS-IUGA scientific meeting and published this summer concludes that there is not enough evidence on single-incision slings compared with retropubic or transobturator slings to allow reliable comparisons, and that additional, adequately powered, high-quality trials with longer-term follow-up are needed (Cochrane Database Sys. Rev. 2014;6:CD008709). However, research completed since the review offers additional data.

For instance, at the 2014 AUGS-IUGA scientific meeting this summer, an oral paper presentation highlighted findings of a randomized controlled trial that showed similar cure rates after surgery with the MiniArc, a fixed single-incision sling, and the Monarc transobturator sling (both by American Medical Systems) at 24 months. The study randomized 234 women to either sling and found no significant differences in subjective outcomes, objective outcomes, or results on various quality-of-life questionnaires.

As such studies are published and more evidence emerges, we will gain a clearer picture of how the newer single-incision slings compare to the well-tested retropubic and transobturator slings with respect to efficacy and safety.

Single-incision slings require only a small vaginal incision and no exit points. Without abdominal or thigh incisions, these new procedures – intended for less severe SUI (no ISD) – may offer improved perioperative and postoperative patient comfort and a potentially decreased risk of surgical injury to the adductor muscles, as well as a decreased risk of vascular and nerve injury. Candidates for these slings may include those who are very athletic, those who are obese, and those with a history of prior retropubic or pelvic surgery.

Research appears to be progressing, but at this time we do not yet have level 1 evidence to support their routine use.

Dr. Sokol reported that he owns stock in Pelvalon, and is a clinical adviser to that company. He also is a national principal investigator for American Medical Systems, and the recipient of research grants from Acell and several other companies.

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.

Sling selection

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.

TVT slings, therefore, appear to be somewhat superior, with statistically significant differences in each of the domains of efficacy and morbidity. Still, surgeon experience and skill remain factors in sling selection; the surgeon who feels comfortable and skilled with a top-down approach and has little experience with a bottom-up approach should continue with SPARC. For surgeons who are skilled with both approaches, it might well be preferable to favor TVT.

Transobturator slings. The transobturator approach was developed to minimize the potential for bladder and bowel injuries by avoiding the pelvic organs in the retropubic space. The sling is introduced either through an inside-out technique, with the needle passed from a vaginal incision and out through the obturator foramen, or through an outside-in technique, with the needle passed through the thigh and then out through the vaginal incision.

A meta-analysis of trials of transobturator sling procedures – including four direct-comparison, randomized controlled trials of the inside-out technique vs. the outside-in technique – showed no significant differences between the two approaches in subjective and objective SUI cure rates in the short term. Rates of postoperative voiding difficulties and de novo urgency symptoms were similar (BJU Int. 2010;106:68-76).

Making a choice. Each of the currently available midurethral slings appears to work well, overall, with few clinically significant differences in outcomes. On the other hand, midurethral slings are not all the same. It is important to appreciate the more subtle differences, to be aware of the evidence, and to be appropriately trained. Often, sling selection involves weighing the risks and benefits for the individual.

On a broad scale, the most recent high-level comparison of the retropubic and transobturator slings appears to be a meta-analysis in which retropubic midurethral slings showed better objective and subjective cure rates than transobturator midurethral slings. Women treated with retropubic slings had a 35% higher odds of objective cure and a 24% higher odds of subjective cure. (The weighted average objective cure rates were 87% for retropubic slings vs. 83% for transobturator slings with a weighted average follow-up of approximately 17 months. The weighted average subjective cure rates were 76% and 73%, respectively.)

Operating times were longer with retropubic slings, but lengths of stay were equivalent between the two types of procedures. This was based on 17 studies of about 3,000 women (J. Urology 2014 [doi: 10.1016/j.juro.2014.09.104]).

The types of complications seen with each approach differed. Bladder perforation was significantly more common with retropubic slings (3.2% vs. 0.2%), as was bleeding (3.2% v. 1.1%). Transobturator slings were associated with more cases of neurologic symptoms (9.4% v. 3.5%) and vaginal perforation (3.6% v. 0.9%).

This new review provides updated information to the 2009 Cochrane Review mentioned above, which reported that women were less likely to be continent after operations performed via the obturator route, but also less likely to have encountered complications. More specifically, objective cure rates were slightly higher with retropubic slings than with transobturator slings (88% vs. 84%) in the 2009 review. There was no difference in subjective cure rates. With the obturator route, there was less voiding dysfunction, blood loss, and bladder perforation (0.3% v. 5.5%).

Other pivotal trials since the 2009 Cochrane Review include a multicenter randomized equivalence trial published in the New England Journal of Medicine in 2010. The trial randomized 597 women to transobturator or retropubic sling surgery, and found no significant differences in subjective success (56% vs. 62%) or in objective success (78% vs. 81%) at 12 months (N. Engl. J. Med. 2010;362:2066-76).

There is some level 1 evidence suggesting that for severe incontinence involving intrinsic sphincter deficiency (ISD), a retropubic TVT sling is the more effective procedure. A randomized trial of 164 women with urodynamic SUI and ISD, for instance, found that 21% of those in the TVT group and 45% of those in the transobturator group had urodynamic SUI 6 months postoperatively.

The risk ratio of repeat surgery was 2.6 times higher in the transobturator group than in the retropubic TVT group (Obstet. Gynecol. 2008;112:1253-61). TVT was more effective both with and without concurrent pelvic organ prolapse repair.

I tell my patients with severe SUI or ISD, therefore, that retropubic sling procedures appear to be preferable. (Exceptions include the patient who has a history of retropubic surgeries, in whom passing the sling through this route may not be the safest approach, as well as the patient who has had mesh erosion into the bladder.)

In patients whose SUI is less severe, I counsel that a transobturator sling confers satisfaction rates similar to those of a retropubic sling and has a lower risk of complications, such as postoperative voiding dysfunction and bladder perforations, but with the possible trade-off of more thigh discomfort. I also might recommend a transobturator sling to patients with more pronounced initial complaints of urinary urgency and frequency, and to patients who have minor voiding dysfunction or a low level of incomplete bladder emptying.

While often short-lived, the small risk of thigh pain with a transobturator sling makes me less likely to recommend this type of sling for a woman who is a marathon runner or competitive athlete. In her case, an analysis of possible complications includes the consideration that bladder perforation can be addressed relatively quickly in the operating room, while persistent thigh discomfort, though relatively rare, could be a debilitating problem.

Single-incision slings

There appears to be emerging evidence suggesting that some of the fixed and adjustable single-incision slings currently available may have efficacy similar to that of the slings that are now widely used.

A Cochrane Review presented at the 2014 AUGS-IUGA scientific meeting and published this summer concludes that there is not enough evidence on single-incision slings compared with retropubic or transobturator slings to allow reliable comparisons, and that additional, adequately powered, high-quality trials with longer-term follow-up are needed (Cochrane Database Sys. Rev. 2014;6:CD008709). However, research completed since the review offers additional data.

For instance, at the 2014 AUGS-IUGA scientific meeting this summer, an oral paper presentation highlighted findings of a randomized controlled trial that showed similar cure rates after surgery with the MiniArc, a fixed single-incision sling, and the Monarc transobturator sling (both by American Medical Systems) at 24 months. The study randomized 234 women to either sling and found no significant differences in subjective outcomes, objective outcomes, or results on various quality-of-life questionnaires.

As such studies are published and more evidence emerges, we will gain a clearer picture of how the newer single-incision slings compare to the well-tested retropubic and transobturator slings with respect to efficacy and safety.

Single-incision slings require only a small vaginal incision and no exit points. Without abdominal or thigh incisions, these new procedures – intended for less severe SUI (no ISD) – may offer improved perioperative and postoperative patient comfort and a potentially decreased risk of surgical injury to the adductor muscles, as well as a decreased risk of vascular and nerve injury. Candidates for these slings may include those who are very athletic, those who are obese, and those with a history of prior retropubic or pelvic surgery.

Research appears to be progressing, but at this time we do not yet have level 1 evidence to support their routine use.

Dr. Sokol reported that he owns stock in Pelvalon, and is a clinical adviser to that company. He also is a national principal investigator for American Medical Systems, and the recipient of research grants from Acell and several other companies.