The nature of urgency

peer-reviewedIntroduction: Many self-help guides advise patients that spreading fluid intake throughout the day can reduce symptoms of overactive bladder (OAB).A,B However, although animal studies suggest a link between faster filling rates and increased afferent nerve firing, the relationship between filling rate and bladder sensation has not been examined in humans. The aim of this research is to investigate the effect of bladder volume and rate of bladder filling on bladder sensation and voiding patterns, in the physiological and pathological bladder in a non-clinical, natural filling environment. Methods: Forty female volunteers (control group) were recruited by open advertisement. A further 24 female patients with OAB were recruited from the urology outpatients department. Each participant completed a UDI-6, IIQ-7 and 3-day sensation-related bladder diary. Results: There was a negative correlation between the rate of bladder filling and the length of intervoiding interval in both groups (p=<0.001). There was a positive correlation between the voided volume and the length of intervoiding interval in both groups (p=<0.001). The proportion of urgent voids in the control group increased with increasing voided volumes (p=<0.001) and bladder filling rates (p=