Preoperative clinical, demographic, and urodynamic measures associated with failure to demonstrate urodynamic stress incontinence in women enrolled in two randomized clinical trials of surgery for stress urinary incontinence.

INTRODUCTION AND HYPOTHESIS: The unexpected absence of urodynamic stress incontinence (USI) in women planning surgery for stress urinary incontinence (SUI) is a challenge to surgeons. We examined the prevalence and clinical and demographic factors associated at baseline (preoperatively) with the unexpected absence of USI among study participants of two multicenter randomized clinical trials of surgery for treating SUI.
METHODS: Women with SUI symptoms and positive stress tests on physical examination enrolled in two separate clinical trials-one comparing the autologous fascial sling with the Burch colposuspension [Stress Incontinence Surgical Treatment Efficacy Trial (SISTEr), and the other comparing the retropubic mid-urethral sling with the transobturator midurethral sling [Trial of Mid-Urethral Slings (TOMUS)]-were evaluated for USI preoperatively. The association of clinical, demographic, and urodynamic parameters was examined in women without USI in univariate and multivariate analyses.
RESULTS: Overall, 144 of 1,233 women (11.7 %) enrolled in the two studies showed no USI. These women had a significantly lower mean volume at maximum cystometric capacity than those with USI (347.5 vs. 395.8 in SISTEr, p = 0.012), (315.2 vs. 358.2 in TOMUS, p = 0.003) and a lower mean number of daily accidents reported on a 3-day diary (2.2 vs 2.7 in SISTEr, p = 0.030) (1.7 vs 2.7 in TOMUS, p < 0.001). Additionally, those without demonstrable USI were more likely to have Pelvic Organ Prolapse Quantification (POP-Q) stage III/IV (31.7 % vs 14.4 % in SISTEr, p = 0.002), (15.5 % vs 6.9 % in TOMUS, p = 0.025). SUI severity as recorded on the Urogenital Distress Inventory (UDI) correlated strongly with the presence of USI in both studies.
CONCLUSIONS: We observed that about one of eight women planning surgery for SUI does not show USI. Stage 3/4 POP was strongly associated with the unexpected absence of USI. A diminished urodynamic bladder capacity among women who did not display USI may reflect an inability to reach the limits of capacity during urodynamics, at which these women normally leak.