Natural volume handwashing urethrocystometry: a physiological technique for the objective diagnosis of the unstable detrusor.

A group of 163 patients attending with a naturally full bladder had urethrocystometric assessment during provocation with a handwashing test. The results were compared with those from a similar group of 169 patients who were subjected to a handwashing test following the infusion of 500 ml of saline with fast-fill cystometry. The latter group was found to have an unacceptably high number of false-positive results. Also, the results appear to indicate that urine loss due to uncontrolled detrusor contraction may be mainly due to premature activation of the micturition reflex. A fall in the intraurethral pressure was found in 79% and a rise in detrusor pressure in 49% of the patients presenting with a prior history of an unstable bladder. Natural urethrocystometry appears to be a useful and informative technique for objectively assessing patients with a prior history of bladder instability.