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Overactive Bladder (OAB)

What is Overactive Bladder (OAB)?

The overactive bladder is characterised by a set of symptoms such as an uncontrollable urge to pass urine and the frequent need to urinate both during the daytime and nighttime. It may also be associated with urge incontinence (urine leakage when one cannot get to the toilet in time due to an overwhelming urge).

OAB’s impact on quality of life

OAB can significantly impact on someone’s quality of life emotionally, socially, physically and financially. Patients find their lives revolving around the toilet and they have to plan their day according to access to a toilet. Some people avoid social situations due to fear of leaking, smell and embarrassment. This can happen to the extent that some rarely leave the house and become a ‘bladder hermit’. Sufferers often feel tired all the time because they are waking up too many times at night to pass urine, and not getting enough rest. They are unable to enjoy a normal diet as they have to restrict both solid and fluid intake in order not to trigger a bladder spasm. Financially, the costs of pads or bladder medications can add up to a significant amount. All these culminate in a sense of loss of control over the bladder and eventually, one’s life.

Questions to ask yourself if you may have OAB

  • Do you have a sudden need to rush to the toilet to urinate?

  • Is this precipitated by hand washing or turning the key in the front door?

  • Have you not made it to the toilet fast enough and leaked urine?

  • How often do you pass urine during the day?

  • Do you always have to know where the toilet is when you are out of the house?

  • During the night, how many times do you get up to urinate? Is it your bladder that wakes you up?

If you have been diagnosed with OAB, take the validated International Continence Society (ICS) questionnaire on OAB – ICIQ-OAB, to assess its severity and impact on quality of life.

Download ICIQ-OAB: International Consultation on Incontinence Questionnaire – Overactive Bladder PDF (275 KB)

What causes it?

Most commonly, there is no known cause for OAB (idiopathic). Some cases are related to a neurological cause such as Parkinson’s, multiple sclerosis or strokes. OAB can also occur secondary to an obstruction of the bladder outlet such as prostatic obstruction in men.

How common is it and is it treatable?

OAB is very common. 1 in 6 over the age of 40 suffers from it, and the incidence increases with age. It is often thought to be more common in women but in reality, it is about as common in men. A lot of people do not seek medical attention and decide to just ‘live with it’. This is unfortunate because there are now a lot of effective treatment options available. Many of these options are now subsidised by Medicare (including sacral neuromodulation).

What other conditions can be mistaken for an OAB?

What are the investigations?

  • Urine test is done to rule out a urinary tract infection.

  • A bladder diary is a useful method of quantifying urinary frequency, volume voided, fluid intake, and leakages. A patient with OAB will show frequent, small voids.

  • A questionnaire (ICIQ-OAB) can be done to get an unbiased assessment of the impact of OAB on a patient’s quality of life. It can also be used to measure treatment outcomes.

  • X-ray imaging is not done routinely, but a kidney ultrasound or CT scan can be useful if:

    • History of possible neurogenic bladder

    • History of pain or blood in the urine

    • Suspicion of anatomical abnormalities

    • A urinary tract ultrasound can measure prostate size (in men), and the volume of urine left in the bladder after a void

  • A cystoscopy is not done routinely unless:

    • Suspect bladder cancer (history of blood in the urine)

    • Bladder pain (rule out bladder pathology like stones or interstitial cystitis)

    • Significant obstructive symptoms (poor flow, straining)

  • Urodynamics or bladder pressure study assesses the function of the bladder. The indications are:

    • Complex history

      • Neurogenic bladder

      • Mixed incontinence (both stress and urge incontinence)

      • Previous pelvic or incontinence surgery

    • Not responding to medications or diagnosis unclear

    • Before invasive surgery

What are the treatment options?

Treatments should always start from conservative ones to more invasive ones.

Conservative treatments

  • Lifestyle changes (reduce caffeine, alcohol)

  • Behavioural therapy (bladder retraining)

  • Medications


Anticholinergic drugs

Medications are the mainstay conservative treatment options. Anticholinergic drugs are most commonly used. They act by ‘calming’ down bladder activity. Common side effects include dry eyes (blurred vision), dry mouth and constipation. Other side effects are confusion, dizziness, rapid heart-beat, and urinary retention (unable to pass urine). Patients with glaucoma should check with their ophthalmologist (eye doctor) before starting on these drugs. These medications achieve maximal effect after 2 to 3 months and hence should be encouraged for that duration before concluding they are not effective.

There are now many drugs in this category such that to a lay person, it may seem confusing. They differ in the number of times taken per day, mode of administration, side effect profile, efficacy and cost. Some of the medications have fewer side effects but are not subsidised by Medicare and hence, are more expensive. Your doctor should be able to discuss with you, which drug is the most appropriate one.

Beta 3 Agonist

Beta 3 agonist (Mirabegron) medication acts via a different pathway compared to the anticholinergic drugs, to treat the overactive bladder. It tends to cause less side effects and is very well tolerated. In some patients, it may cause a slight rise in the blood pressure. This drug is now available in Australia.


In men with OAB secondary to obstruction from an enlarged prostate, another class of drugs may be tried first (alpha-blockers) to improve the obstruction. Sometimes, this will result in an improvement of the OAB symptoms over time. In those that don’t, an anticholinergic medication can be added to treat the OAB symptoms.


Minimally invasive surgical treatments:

In the past, surgical options are highly invasive and involve major surgery. The advent of minimally invasive techniques (anti-spasm bladder injection and sacral neuromodulation) has revolutionised the treatment of drug-refractory OAB (those not responsive to medications).

  • Anti-spasm bladder injection

    • This has now been approved by Medicare in Australia for patients with the neurogenic bladder (spinal cord injury, spina bifida, multiple sclerosis) and idiopathic OAB (from Nov 2014).

    • This outpatient procedure is done during a cystoscopy and takes about 15 minutes to do. It is effective in about 70% of patients.

    • The effects wear off over time, and patients would need a ‘top-up’ every 6 to 10 months.

  • Sacral neuromodulation (bladder pacemaker)

    • Involves 2 stages; a trial stage and an implant stage

    • A small electrode is first inserted into the lower back (sacral spine) to lie next to a sacral nerve root.

    • This trial stage lasts about 2 weeks and if the patient shows improvements in symptoms, then a permanent battery is implanted.

Major surgery

  • Augmentation cystoplasty

    • A piece of small bowel tissue is reflected and sutured onto an opened bladder to create an ‘augmented’ bladder in terms of volume and ability to maintain a low pressure within it.

    • Overactive bladder contractions are dissipated over this larger volume and become less symptomatic and less dangerous to the kidneys.

    • Some patients may need to learn to do intermittent self-catheterization if the bladder does not empty well.

    • The bowel segment of the augmented bladder will continue to produce normal mucous, which will mix in with normal urine.

    • There is an increased risk of bladder stone formation.

    • Routine yearly cystoscopy would have to be performed, as there is a very small risk of the bowel segment undergoing malignant transformation over time.

  • Urinary diversion

    • This is usually done as a last option.

    • Urine can be surgically diverted by implanting the ureters (tubes draining the kidneys to the bladder) to a piece of small bowel. This then exits to the abdominal skin surface (stoma) into a bag.