Diagnostic Value of the Maximum Urethral Closing Pressure in Women With Overactive Bladder Symptoms and Functional Bladder Outlet Obstruction

Purpose: Overactive bladder (OAB) is observed in women with functional bladder outlet obstruction (FBOO), as are lower urinary tract symptoms (LUTS). Therefore, we evaluated the urodynamic characteristics of women with storage LUTS and FBOO diagnosed by urodynamic studies (UDS). Methods: Women (n=108) with storage LUTS and FBOO diagnosed by UDS were included in this study. The urodynamic characteristics of women with FBOO were compared with those of women with OAB (n=34) and stress urinary incontinence (SUI, n=78). FBOO was defined as a maximum flow rate (Qmax) < 15 mL/sec, combined with detrusor pressure at a Qmax (PdetQmax) > 20 cm H2O in a pressure-flow study. The UDS included uroflowmetry, postvoid residual volume determination, a cystometrogram, and a pressure-flow study. Results: Women with FBOO who had storage symptoms showed a higher PdetQmax and maximum urethral closing pressure (MUCP) than women with OAB and SUI. Interstitial cystitis/bladder pain syndrome (IC/BPS) was observed in 17.6% of women with FBOO. MUCP was significantly higher in women with BOO than in women with BOO and IC/BPS (115.6±27.4 and 96.6±14.1 cm H2O, P=0.00). The receiver operating characteristic curve analysis showed that the cutoff values of MUCP in women with FBOO compared to women with OAB and SUI were 87 cm H2O (sensitivity=81.5%, specificity=73.5%) and 36 cm H2O (sensitivity=92.6%, specificity=84.4%), respectively. The cutoff value of MUCP in women with FBOO compared to women with FBOO and IC/BPS was 92 cm H2O (sensitivity=85.4%, specificity=78.9%). Conclusions: MUCP could have predictive value for identifying FBOO in women with complex LUTS.