A 2009 Cochrane review identified 62 trials with over 7,000 women in which minimally invasive sling was studied in at least one arm (107). Most were of poor to moderate quality with short follow-up. Minimally invasive synthetic suburethral sling operations appeared to be as effective as traditional suburethral slings but with shorter operating time and less postoperative voiding dysfunction and de novo urgency symptoms. Similarly, minimally invasive synthetic suburethral slings were as effective as open retropubic colposuspension with fewer perioperative complications, less postoperative voiding dysfunction, shorter operative time and hospital stay, but significantly more bladder perforations (6% vs. 1%). A retropubic bottom-to-top route was more effective than top-to-bottom route and was associated with significantly less voiding dysfunction, fewer bladder perforations, and tape erosions. At the time of this review, 17 trials comprising 2,434 women compared the transobturator route with the retropubic route of sling placement. The transobturator route had a slightly lower objective cure rate (84% vs. 88%) but had less voiding dysfunction, blood loss, bladder perforation, and shorter operating time.
After the publication of this Cochrane review, the largest (597 women) randomized equivalence trial to date comparing retropubic and transobturator sling approaches was published by the Urinary Incontinence Treatment Network (108). Women were randomized in the operating room and were followed for 1 year. The primary outcome was treatment success at 12 months according to both objective criteria (a negative stress test, a negative pad test, and no retreatment) and subjective criteria (self-reported absence of symptoms, no leakage episodes recorded, and no retreatment). Objective success rates were 80.8% and 77.7% and subjective success rates were 62.2% and 55.8%, in the retropubic and transobturator groups, respectively. Women in the retropubic group had more voiding dysfunction (2.7% vs. 0%), while those in the transobturator group had a higher rate of neurologic symptoms (9.4% vs. 4.0%). There were no significant differences between groups in postoperative urge incontinence, satisfaction with the results of the procedure, or quality of life.
A third generation of minimally invasive slings was developed, the so-called minislings. Insertion of the minisling requires only a single vaginal incision, less dissection, and the potential to be placed in a clinic setting. Data are mixed, with some finding equivalent success rates and others up to eightfold higher failure rates in the minisling group than in the full-length synthetic sling (109,110).