To assess the evolution of bladder voiding dynamics from the onset of symptoms to the final diagnosis of idiopathic detrusor underactivity (DUA) in men with storage and voiding lower urinary tract symptoms (LUTS) and otherwise normal clinical findings.

We retrospectively analyzed the urodynamic findings in two patient groups of 25 men each. Group A, with storage and voiding LUTS and otherwise normal clinical findings, had an inconclusive urodynamic test at time 1 and were re-assessed after a mean (± SD) of 17 ± 5 months for worsened symptom severity (time 2). The control group B was formed by age-matched men with unexplained recurrent urinary tract infections who, when seen by us, showed normal clinical and urodynamic findings. Nonparametric statistics were checked for significant differences between groups A and B and between times 1 and 2 in group A.

At time 1, group A had moderately high symptom scores, but the urodynamic findings (normal detrusor contraction strength with a lower detrusor contraction velocity than in group B) seemed to be inconclusive; thus no clear-cut diagnosis was made. At time 2, compared with time 1, group A had higher symptom scores, and the urodynamic findings (lower detrusor contraction strength and shortening velocity, unchanged urethral resistance, lesser voiding efficiency) suggested a diagnosis of idiopathic DUA.

Idiopathic DUA would likely imply a two-stage development (ie, would be preceded by a phase of low detrusor contraction velocity occurring even several months before a decrease in detrusor contraction strength).