• bladder filling phase;
  • bladder sensation;
  • detrusor overactivity;
  • urodynamic

Objectives: During bladder filling, the bladder starts to sense it and the sensation steadily increases. However, little is known concerning volume-sensory correlation in normal bladder and pressure-sensory correlation during detrusor overactivity (DO). We aimed to real-time assess bladder sensation in normal bladder and DO using a five-grade measure.

Methods: We enrolled 74 normal individuals and 87 patients with DO (51 terminal, 36 phasic). During slow bladder filling, we instructed individuals to indicate sensation in five grades: 1, first sensation; 2, obviously greater than 1 but less than 3; 3, first desire to void when he or she usually goes to toilet; 4, obviously greater than 3 but less than 5; and 5, strong desire to void. We also instructed individuals to report other sensations, such as pain.

Results: The five-grade measure is feasible in all participants, showing a volume and pressure- sensory correlation. Among the five grades, grade 0 to 1 was the longest, followed by grade 4 to 5, in all participants. Grade 0 to 1 in phasic DO and grade 4 to 5 in terminal and phasic DO were shorter than those in normal bladder (P < 0.05). Eighty-six percent of patients with DO reported that the rapidly increased sensory grade is akin to urinary urgency in daily life.

Conclusion: The five-grade measure is feasible to assess a volume and pressure-sensory correlation. Using this measure the sensory grade rapidly increased during DO compared with normal bladder, and 86% of the patients with DO reported that it is akin to urinary urgency in daily life.