Influence of intravesical potassium on pelvic floor activity in women with overactive bladder syndrome: comparative urodynamics might provide better detection of dysfunctional voiding

Objective To assess the influence of intravesical potassium on pelvic floor activity (PFA) during voiding in women with symptoms of overactive bladder (OAB), by using comparative urodynamics (CUD). Patients and Methods The study included 175 women who met the criteria of OAB (mean age 52.7 years, range 18-87). CUD included two sessions of pressure-flow studies (0.9% saline vs 0.2 M KCl) with simultaneous measurement of PFA using perineal electromyography (EMG) with surface electrodes. Dysfunctional voiding (DV) was diagnosed if significant PFA was measured by EMG during voiding. Results In 44 patients (25%) there was increased EMG activity only in the presence of KCL; in 58 (33%) there was DV with increased PFA during filling with saline. In all these patients PFA was significantly greater in the presence of KCl (P < 0.001). In patients with DV, filling with KCl prompted a statistically significant difference in maximum bladder capacity, maximum flow rate, mean flow rate and postvoid residual urine volume (P < 0.05). In summary, 102 patients (58%) had DV. Conclusion These findings suggest that DV is associated with epithelial dysfunction of the bladder mucosa, which clinically leads to OAB syndrome and can be revealed by CUD. The detection of DV might elude conventional urodynamics, but can be significantly enhanced by CUD (0.9% saline vs 0.2 M KCl).