Transobturator slings for stress incontinence: using urodynamic parameters to predict outcomes

The purpose of this study is to evaluate the ability of preoperative urodynamic urethral function parameters to predict the success rate of transobturator slings (TOS). Seventy women urodynamically diagnosed with stress incontinence with urethral hypermobility underwent a Monarc TOS (American Medical Systems, Minnetonka, USA). Postoperative continence status was correlated with preoperative urodynamic urethral function parameters. Mathematical modeling was used to determine whether urodynamic parameters can be used to predict postoperative continence. Average follow-up was 8.1 (6-12) months; 56 (80%) patients were continent based on a standardized stress test and subjective report. The median Valsalva leak point pressure at 150 cc (VLPP150) in the failures and successes was not different (p = 0.12). The median VLPP at cystometric capacity (VLPPcap) in the failures was 32 cmH2O compared to 71 cmH2O in the successes (p < 0.001). The maximum urethral closure pressure (MUCP) had a median of 20 cmH2O in the failures and 45 cmH2O in the successful patients (p < 0.001). No correlation existed between the degree of urethral hypermobility, as measured by the cotton swab test, and surgical success (p = 0.17). There was no correlation between level of preoperative urethral function and persistent overactive bladder symptoms, post-void residual, voids/day, and nocturia. Using a combined model, the cutoff values of VLPPcap > 60 cmH2O and MUCP > 40 cmH2O were the most predictive of surgical success, revealing a sensitivity of 83% (0.55, 0.95) and specificity of 79% (0.67, 0.88). A combination of urodynamic parameters can be used to predict continence rates after a TOS. A TOS should be used with caution in women with impaired urethral function.