How sudden is a compelling desire to void? An observational cystometric study on the suddenness of this sensation

To evaluate whether a compelling desire to void (CDV) is always perceived suddenly, or whether it can result from the gradual build-up of bladder-filling sensations.

The pattern of filling sensations was evaluated during standard cystometric bladder filling in 75 patients who complained of urgency and showed detrusor overactivity during cystometry. Cystometric filling ended when a CDV was reported. The 'warning volume' is defined as the difference in volume between the first perception of filling and the volume at CDV.

Different patterns of bladder-filling sensations were reported. A CDV occurred suddenly, without a preceding sensation in 13% of the patients, whereas 66% reported at least two normal preceding filling sensations before a CDV. The bladder volume at the CDV was significantly smaller in patients that reported no or just one preceding sensation compared with those that reported the normal pattern of two or three sensations (P < 0.005). The bladder volume at which the first filling perception was reported was not different regardless of whether it was described as a first sensation of filling, a first desire or a CDV (P = 0.42). The warning volumes were not different between patients with one or no standardized filling sensations (P = 0.7), but they were significantly smaller than in patients with two or three filling sensations (P = 0.85).

A CDV can occur suddenly if normal filling sensation is disturbed, but also gradually if normal filling sensation is preserved. In cases of disturbed filling sensation, the volume at CDV and the warning volume are significantly lower.