What is an Underactive Bladder?
An underactive bladder (also known as detrusor underactivity) is defined as a bladder which has a contraction of reduced strength and/ or reduced duration, which results in prolonged or slow bladder emptying or inability to completely empty the bladder within a normal time span.
Paradoxically bladder underactivity can co-exist with an overactive bladder i.e. the bladder can contract out of a person’s control (bladder or detrusor overactivity) but with an impaired bladder contraction that does not empty the bladder normally (bladder underactivity).
How common is an Underactive Bladder?
The prevalence of underactive bladder has been mainly studied in older populations. In some studies of people older than 65, up to 40% of men and 13% of women had evidence of an underactive bladder.
In men the underactive bladder may co-exist with an overactive bladder and bladder outlet obstruction most commonly due to benign enlargement of the prostate that occurs with ageing.
In women the underactive bladder may co-exist with an overactive bladder or stress incontinence.
What are symptoms of an Underactive Bladder?
Symptoms of an underactive bladder include:
- Needing to wait for the flow to start or hesitancy
- Needing to push and strain to empty the bladder
- Poor or slow urinary stream
- Stop and start urinary stream
- Prolonged time required to pass urine
- Feeling like the bladder has not emptied completely
- Needing to go back a second time shortly after passing urine to pass more urine
- Reduced sensation of bladder fullness
- Frequent urination
- Urge urinary incontinence
In severe cases of an underactive bladder, “overflow” urinary incontinence can occur. Overflow urinary incontinence occurs when the bladder does not empty fully and is chronically over distended.
The symptoms of an underactive bladder overlap significantly with other bladder conditions especially bladder outlet obstruction (i.e. blockage to the outflow of urine from the bladder) as well as an overactive bladder.
As a result, an underactive bladder requires further assessment with tests such as an ultrasound and Urodynamic testing to make the diagnosis.
What are the causes of an Underactive Bladder?
The causes of an underactive bladder are divided into 3 categories:
- Neurogenic – related to abnormalities of the nerve supply of the bladder
- Myogenic – due to a problem with the muscle of the bladder also known as the detrusor muscle
- Idiopathic – where the cause cannot be identified
Neurogenic causes of an underactive bladder, include:
- Central nervous system conditions such as Multiple Sclerosis and Parkinson’s disease
- Peripheral nervous system injuries which are often due to pelvic surgeries or trauma that can result in injuries to the nerves supplying the bladder e.g.:
- Abdominoperineal resection (a bowel operation for rectal cancer), radical hysterectomy for uterine cancer
- Pelvic and sacral fractures or injury to the cauda equina nerves from disc prolapse
- Infections which can affect the nervous system e.g.: herpes zoster, Guillain-Barré syndrome
Myogenic causes of an underactive bladder include:
- Chronic overdistension or overstretching of the bladder e.g.:
- Due to chronic blockage of the bladder outflow from benign enlargement of the prostate in men
- Due to severe chronic pelvic organ prolapse in women
- Rarely due to abnormal learned voiding patterns
Idiopathic underactive bladder:
- Idiopathic bladder underactivity is identified when no neurogenic or myogenic causes can be identified.
- Some studies have attributed bladder underactivity to ageing whereas others have not found a correlation with ageing. It is likely that there are many factors including age that contribute to the cause of bladder underactivity in the elderly.
How is an Underactive Bladder diagnosed?
An underactive bladder cannot be diagnosed purely on symptoms as other bladder conditions can have the same symptoms with a completely different cause and treatment e.g. bladder outlet obstruction.
Non-invasive tests are initially used to investigate an underactive bladder including:
- Flow rate test – where the speed at which urine is passed is measured by passing urine into a toilet containing a special flow meter device
- Residual volume ultrasound – which is an assessment of the volume of urine left behind in the bladder immediately after urination as measured by an ultrasound scan of the bladder
- Bladder diary
A Urodynamic study gives the definitive diagnosis of an underactive bladder as it is able to distinguish between poor detrusor function and blockage within the urinary tract. The Urodynamic study is often combined with a cystoscopy to give further information about the anatomy of the urethra and bladder as well as the prostate in men.
What treatment options are available for an Underactive Bladder?
- Observation – Especially if the patient is not significantly bothered by their symptoms and their residual volumes are not excessive or continuing to rise. Monitoring is required with checks of flow rate and residual bladder volume (i.e. the volume of urine left behind in the bladder after urination measured with an ultrasound of the bladder). This form of management can be used in:
- Patients who are not significantly bothered by their symptoms and who
- Do not have complications from incomplete bladder emptying such as recurrent urinary tract infections, overflow urinary incontinence, severe impairment of bladder emptying or deterioration in kidney function.
- Unfortunately the natural history or progression of an underactive bladder is not clear in any individual and monitoring should occur to ensure the problem does not progress to a bladder muscle that does not contract.
- Timed voiding - This is a technique of voiding at timed intervals (e.g. every 3 to 4 hours) instead of relying on a sensation of bladder fullness that may be dulled in some people with an underactive bladder. Timed voiding aims to avoid over distension of the bladder.
- Pharmacological management.
- Unfortunately there are no drugs currently available which reliably or consistently improve the bladder muscle’s contraction.
- Bethanechol is a medication, which stimulates certain receptors found in the bladder (muscarinic receptors). Unfortunately studies have not shown it to have an advantage over placebo in improving symptoms or bladder emptying and hence it is now not commonly used.
- Tamsulosin (Flomaxtra®) is a medication, which blocks messages in alpha-adrenergic receptors, which are found at the bladder outlet. Tamsulosin causes relaxation of smooth muscle at the bladder outlet that can help reduce resistance to passing urine. Tamsulosin can help improve urine flow and bladder emptying in some women and men.
Intermittent self-catheterisation (ISC)
- Intermittent self-catheterisation or ISC (also known as CIC or clean intermittent catheterisation) is a technique whereby the patient is taught to empty the bladder by passing a catheter into the bladder to drain out urine, which is then immediately removed.
- The procedure is taught to the patient by specialist Urology or Continence nurse using disposable catheters.
- The frequency of performing intermittent self-catheterisation varies according to the degree of bladder underactivity and may be performed once or more per day.
- Intermittent self-catheterisation is the preferred non-surgical treatment for an underactive bladder.
Indwelling catheters (or permanent catheters)
- Ideally a permanent indwelling catheter should be avoided except in cases in which intermittent catheterisation cannot be performed by the patient or a caregiver as indwelling catheters are associated with more infections and long term problems than intermittent catheterisation.
- A long-term suprapubic indwelling catheter (i.e. entering the bladder through the abdomen rather than through the urethra or water pipe) is a better long-term option than a urethral catheter as it prevents complications affecting the urethra.
- Neuromodulation with the InterStim® neuromodulation device
- This device is sometimes an appropriate option in patients with an underactive bladder.
- InterStim® therapy is approved for usage by Medicare in Australia in people older than 18 years of age who have either an overactive bladder or problems with bladder emptying due to an underactive bladder in the absence of a blockage in the urinary tract which has not responded to other treatments (such as intermittent self catheterisation) over at least a 12 month period.
- The results of InterStim® neuromodulation for incomplete bladder emptying are promising but variable. Further research is required to determine which patients are the best candidates for treatment with InterStim®
- Surgery to treat bladder outlet obstruction
- Surgery with TURP (transurethral resection of the prostate) in men who are shown to have obstruction from prostatic enlargement has been shown to significantly improve voiding symptoms.
Consultation for Underactive Bladder
If you believe you may be experiencing an Underactive Bladder and would like to discuss with Dr McKertich, please call us or make an appointment request. A valid GP or specialist referral is required to make an appointment.