Commentary
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.