No significant difference was noted between the groups in the primary outcome, which was the rate of bladder perforation (TVT, 0.7%; SPARC, 1.9% [p=.62]). This effect remained after controlling for age, parity, prior urinary incontinence surgery, other concomitant surgery, and the surgeon’s level of experience. There were no intergroup differences in perioperative blood loss, urgency, or objective cure of SUI (defined as negative cough stress test) 6 weeks after surgery.
Subjects who underwent SPARC were more likely to experience urinary retention that required surgical readjustment of the sling (SPARC, 10 of 154; TVT, none [p=.002]). Although the objective cure rate was similar across groups, the subjective cure rate was significantly different (TVT, 87.1%; SPARC, 76.5% [p=.03]).
Regression analysis revealed that subjects who had prior surgery for urinary incontinence and those whose surgery was performed by a comparatively less experienced physician were more likely to report persistence of SUI symptoms.
This study reflects general clinical practice, in that it was conducted across a heterogeneous sample of subjects who had both primary and recurrent stress incontinence. Although the rate of bladder perforation was equivalent across groups, more patients who underwent SPARC required loosening of the sling postoperatively to relieve urinary retention.
These data suggest that the SPARC sling may be more difficult to adjust correctly even though it is designed with a tensioning suture. The difficulty may be a consequence of 1) smaller-caliber trocar tunnels or 2) the “top-down” approach less accurately locating the sling at the midportion of the urethra.
This study would have been more rigorous and the results, stronger, if postoperative assessment was made by a blinded examiner. An exceptional positive aspect of study design was that the investigators considered the surgeon’s level of experience—a variable that can certainly affect outcome.
Barber MD, Kleeman S, Karram MM, et al. Transobturator tape compared with tension-free vaginal tape for the treatment of stress urinary incontinence. Obstet Gynecol. 2008;111:611–621.
This randomized, controlled trial compared the efficacy of TVT with the transobturator tape (TOT) technique. Like Lord and colleagues’ study just discussed, it was conducted as an equivalence trial—to determine whether TOT is equivalent to TVT.
The primary outcome was abnormal bladder function 12 months after surgery, defined as the presence of any of the following:
- incontinence symptoms
- positive cough stress test
- retreatment for SUI
- treatment for postoperative urinary retention.
Women who had urodynamic stress incontinence were recruited from three academic centers; excluded were women who had detrusor overactivity, postvoid residual volume >100 mL, prior sling surgery, or contraindications to a midurethral sling.
For the retropubic approach, TVT was used. For the transobturator approach, the Monarc Subfascial Hammock (American Medical Systems) was used. Here, the tape is placed in an “outside-in” fashion.
Subjects completed a baseline bladder diary and a series of validated questionnaires. Postoperatively, subjects were followed for 2 years. Follow-up data included validated questionnaires, bladder diary, pelvic organ prolapse quantification, cough stress test, and postvoid residual volume determination. It was not possible to blind subjects or surgeons, but all postoperative assessments and exams were performed by a blinded nurse.
The investigators sought to determine if TVT and TOT yielded an equivalent (within a 15% margin) rate of abnormal bladder function.
Eventually, 170 patients underwent randomization and surgery (88, TVT; 82, TOT). Baseline demographic, clinical, and incontinence severity data were similar across groups.
Bladder perforation was more common with TVT than with TOT (7% and 0, respectively [p=.02]). Abnormal bladder function was noted in 46.6% of TVT subjects and in 42.7% of TOT subjects, with a noninferiority test demonstrating equivalence (p=.006). One year after surgery, 79% of patients in the TVT group and 82% of patients in the TOT group reported that bladder symptoms were “much better” or “very much better” (p=.88). No significant difference was noted between groups in any of the questionnaire responses after surgery.
This study has many strengths, including rigorous assessments, use of a blinded nurse-examiner to collect postoperative data, and a battery of validated questionnaires used throughout the study. In addition, the primary outcome measure, abnormal bladder function, is defined by stringent criteria that combine subjective and objective components, efficacy, and adverse events.
It will be interesting to see if the efficacy of TOT is maintained over time. The authors of the article point out that several transobturator sling kits are available, utilizing various trocar shapes, different approaches (i.e., “in to out”), and different types of mesh; this may mean variable rates of complications and different degrees of efficacy from one kit to the next.