Bladder sensory power factor (BSPF): a novel diagnostic tool

A simple clinical test for assessment of sensory function of the urinary bladder is described. It is performed during urodynamic assessment, consisting of stepwise filling of the bladder by gas. Subjects give numerical description of the perceived magnitude of pressure at each step, using an open-ended ratio scale. Based on Stevens law of psychophysics, the bladder sensory power factor (BSPF) is extracted from these data, reflecting the sensory state of the bladder. A BSPF of 1.01 +/- 0.12 (mean +/- SD) was found for 13 normal subjects. For 20 patients with lower urinary tract complaints who had a lesion of lumbosacral nerve roots, the BSPF was 0.59 +/- 0.23 (P < 0.001, t-test). In 16 (80%) of them BSPF was lower than 0.77 (= normal mean -2 SDs), being markedly more sensitive than the punctual sensory parameters-bladder sensory threshold (25%) or capacity (35%). BSPF is presented as a sensitive and easy to perform test for assessment of the sensory function of the human urinary bladder.