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How to diagnose overactive bladder

Remember overactive bladder (OAB) is a symptom complex of urinary urgency, with or without urge incontinence, frequency and nocturia. Find out more about different types of OAB and about urodynamics which can help to diagnose the cause of bladder dysfunction.

Clinical practice points. In practice a clinical diagnosis of OAB is made based on clinical symptoms the patient describes. Your treatment decisions will be based mainly on what the person tells you. This is why it is so essential to listen to your patient and to ask the right questions. You will learn more about this in week 5.

To identify OAB look for indications of these symptoms including:

  • Urgency - on an urgency scale of 0-4, where 4 is highest
  • Frequency – more than seven voids a day, could be several times an hour
  • Low voided volumes - 20, 50, 100, 150ml or less (resulting in decreased bladder capacity)
  • If OAB wet – variable sized wet patches because unstable bladder contraction can happen at any level of bladder filling
  • Nocturia - night-time waking to void
  • Poor stream - (constantly voiding small volumes)
  • Feeling of incomplete bladder emptying - bladder not filling effectively
  • Reduced fluid intake
  • Concentrated urine
  • Constipation

Patients are encouraged to fill in a bladder diary. An sample bladder diary is available for you to view in PDF format.

Aggravating factors include:

  • Caffeine
  • Alcohol
  • Anxiety/fear
  • Constipation

Your task

Consider the symptoms above and list the ones your patients describe most often.

Do you think there any symptoms missing? Share your thoughts with fellow learners.

Types of OAB

OAB is a clinical diagnosis. It may be separated into idiopathic, neurogenic and sensory urgency.


Idiopathic OAB (of unknown cause) forms the majority of cases.


Neurogenic OAB arises from the nervous system.

Neurological lesions resulting from strokes, Alzheimer’s disease, multiple sclerosis, spinal cord injuries, Parkinson’s disease and others cause a loss of inhibitory impulses from the frontal cortex of the brain.

The sacral reflex arc becomes more dominant, resulting in frequent, spontaneous contractions of the detrusor muscle during the filling phase.

Increased sensory input from the bladder such as, urinary tract infection, faecal impaction, prostatic enlargement, bladder stones, bladder tumours.

Sensory urgency

Sensory urgency often presents after an individual has had a urinary tract infection. At low levels of bladder filling, perhaps only 25ml, the person experiences a strong urgent desire to void, feels that their bladder is full, rushes to the toilet but can only pass a small volume of urine with a poor stream.

This could occur 3-4 times an hour, resulting in a daytime frequency of 20+ times. In most cases there is no wetting.

In most cases this is a daytime problem only (no nocturia) and the person will void a normal volume in the morning of 300-400ml. Sensory urgency can be very effectively and quickly treated, with an explanation about what is happening, and advice about bladder training.

The person has the bladder capacity but is receiving the wrong messages.


Urodynamics are clinical investigations undertaken to assess how the bladder and urethra are storing and releasing urine.

They help to diagnose the cause of bladder dysfunction. Urodynamic studies (UDS) use clinical procedures such as cystometry and uroflowmometry to investigate and measure different aspects of bladder functioning.

The investigations look at muscle function, mechanics, and nerve responses of the bladder and urinary tract. UDS can tell if a person is experiencing OAB because of detrusor overactivity (DO), which is sub-divided into neurogenic detrusor overactivity (NDO) or idiopathic detrusor overactivity (IDO).

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This article is from the free online course:

Understanding Continence Promotion: Effective Management of Bladder and Bowel Dysfunction in Adults

Association for Continence Advice

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