The unstable bladder.

The unstable bladder is a common clinical problem of uncertain aetiology. Current in vitro studies of unstable human detrusor samples show differences in behaviour and response to pharmacological agents from normal detrusor. The fundamental urodynamic abnormality is the occurrence of involuntary detrusor contractions which cause the cardinal symptom of urgency. The incidence of other symptoms is determined by the functional bladder capacity and the patient's ability to resist the unstable contractions. Having excluded outflow obstruction as a causative or associated factor, empirical treatment may reasonably be started on the basis of the findings of a 48-hour voided volume chart, reserving full urodynamic investigation for patients who fail to respond to treatment as expected. For those with minimal urodynamic dysfunction, bladder drill is the treatment of choice; when this fails or is inappropriate, drug treatment with oxybutynin is indicated, supplemented by other drugs when appropriate. When these standard conservative measures fail, transvesical injection of the pelvic plexuses with phenol gives worthwhile results and is a trivial procedure. If this fails, and in men in whom the phenol procedure is contraindicated, 'clam' ileocystoplasty is usually if not always curative.