Underactive bladder is gaining increased attention as a clinical entity that tends to occur predominantly in older adults. Symptomatically this condition most often manifests as urinary retention with incomplete bladder emptying. The condition can also be associated with other lower urinary tract symptoms such as urinary urgency, frequency, nocturia and poor urinary stream. In men this condition can be challenging to differentiate from symptoms caused by bladder outlet obstruction. Detrusor underactivity, a component of the underactive bladder syndrome, has not been clearly defined from a physiological perspective.
This study was conducted to create a nomogram for voiding parameters initially in a cohort of healthy men 40 years or older without voiding abnormalities. The model was then verified using retrospective analysis of urodynamic data from 822 older men with voiding dysfunction. Based on this analysis, measurements below the 25th percentile were associated with clinical indicators of detrusor underactivity. This finding provides an initial urodynamic measure that can be used to help differentiate detrusor underactivity from bladder outlet obstruction. Detrusor underactivity was associated with increased age, bladder capacity and post-void residual volume, and poorer voiding efficiency. These data can be used to help in the ongoing process of defining this complex clinical entity and as a predictive variable outcome measure in future research.