Aims: To obtain improved assessment of bladder sensitivity during cystometry by using a 10 cm visual analogue scale (VAS), and comparing it with the standard method according to the International Continence Society (ICS).
Methods: Twenty-five patients with presumed normal bladder functioning underwent filling cystometries according to the VAS-based method and to the standard method. The order of the cystometries was set by randomization. The relationships between the bladder sensation using the VAS-based method and the volume of bladder perfusion were analyzed graphically. Various parameters were abstracted and compared to those obtained by the standard method. Correlations were searched for by principal component analysis.
Results: All the curves showed continuous progression of the desire to void. Eighteen of the 25 curves (72%) had a characteristic appearance, showing a latency phase with no perception of any bladder sensation, then a second phase with linear increase of the desire to void. The latency phase corresponded to the first sensation of bladder filling (226.3 ml +/- 169.1 vs. 200.0 ml +/- 143.1, r = 0.9). The progression in desire measured by the VAS method culminated in a sensation of maximum tolerable desire to void, which corresponded to the maximum cystometric capacity (MCC; 497.3 +/- 191.2 vs. 517.4 +/- 196.7, r = 0.9). The slope of the linear regression line for the desire to void constitutes an independent parameter.
Conclusions: VAS reveals that the distinct sensations with the standard method are in fact a single sensation of a desire to void that increases continually during filling.