unstable bladder

Last reviewed 01/2018

Detrusor instability is characterised by spontaneous and uninhibited contraction of the detrusor muscle during bladder filling. The bladder pressure exceeds the urethral pressure resulting in incontinence (the urethral opening pressure is higher in women with detrusor instability than in those with stable bladders).

It may complicate multiple sclerosis or a stroke but in most cases, the cause is unknown.

The symptoms are those of urge incontinence.

Diagnosis can be made only on cystometry, spikes of increased intravesical pressure appearing without the specific instruction to void, and which cannot be inhibited.


  • overactive bladder syndrome (OAB) is defined as urgency that occurs with or without urge UI and usually with frequency and nocturia. OAB that occurs with urge UI is known as 'OAB wet'. OAB that occurs without urge UI is known as 'OAB dry'.

    • these combinations of symptoms are suggestive of the urodynamic finding of detrusor overactivity, but can be the result of other forms of urethrovesical dysfunction


  1. NICE (October 2006). Urinary incontinence - The management of urinary incontinence in women