A possible link between stress urinary incontinence and detrusor instability in the female--urodynamic (pressure/flow) data and speculative considerations.

The aim of the present investigation was to check voiding mechanics in women with stress urinary incontinence (SUI) for differences between patients with stable bladders and those with detrusor instability (DI). There were 70 females, 35 with stable and 35 with unstable bladders, who had urodynamically proven SUI. All underwent medium-fill water cystometry and pressure/flow studies. A relatively enhanced detrusor contractility, mirrored by higher values of maximum external voiding power and shortening velocity, could be found in the unstable patients. Of these, 27 were reassessed urodynamically following surgical cure of the SUI. After the operative treatment 17 of the 27 showed stable bladders and a reduced detrusor contractility, but no reduced contractility was found in the other 10, whose bladders remained unstable. The data reported may suggest that the factor responsible for 'idiopathic' DI in SUI patients would also be able to yield enhanced bladder mechanical capability. It was tentatively assumed that this factor involves an increased urethral sensitivity, possibly secondary to incompetence of the urethral closure mechanism, and persisting at times even should SUI be surgically relieved.