38 CLINICAL FOCUS
38 CLINICAL FOCUS
19 SEPTEMBER 2025 ausdoc. com. au
| THE | WOMEN’ S AND MEN’ S HEALTH SPECIAL
NEED TO KNOW
Therapy Update
Treating the
overactive bladder
Overactive bladder( OAB) is a clinical diagnosis. 1
It is common, affecting 10-15 % of women, with increasing prevalence with age. 2
It is generally classed as OAB dry or wet depending on the association with leakage of urine.
There are numerous causative factors. Not all patients have detrusor overactivity on urodynamics.
Urogynaecology
Dr Rebecca Young is a subspecialist urogynaecologist with appointments at Royal North Shore Hospital and North Shore Private Hospital, St Leonards, Sydney, and Sydney Adventist Hospital, Wahroonga, Sydney.
The recognition and treatment of this common condition can significantly improve quality of life for affected women.
OVERACTIVE bladder( OAB) is a clinical syndrome defined as urinary urgency, with or without urgency urinary incontinence, usually with increased daytime frequency and nocturia. This occurs in the absence of proven infection or other obvious pathology as the cause. 1
Symptoms are typically due to an‘ unstable bladder’ and are often associated with detrusor overactivity. Although it is idiopathic, potential underlying causes have been identified. The main causative factors are outlined in box 1. 2, 3
Ongoing research includes investigation of the impact of hormones on bladder function as well as the effect of the urinary microbiome. The interplay of these factors has led to the differentiation of various OAB subtypes. Identification of these and further research into their mechanisms will hopefully improve treatment outcomes in the future.
Epidemiology
The prevalence of OAB varies between 9 % and 43 % in women based on population-based studies, but most likely sits at 10-15 %. 2, 4 Both the prevalence and severity of symptoms increase with age. In 30-40 % of women, symptoms resolve temporarily or long term. However, for most patients, it is a chronic condition that requires ongoing management. 2
Assessment
Patient assessment requires a careful history. This should review the symptoms and severity( see box 2).
Contributing factors such as the patient’ s fluid intake( total water intake as well as use of caffeine, alcohol and carbonated beverages), smoking history, menopausal symptoms, prolapse symptoms and bowel function should be discussed. Neurological symptoms need to be excluded.
Examination includes basic neurological, abdominal and pelvic exams. Urina lysis can help exclude infective causes as well as identify haematuria and glycosuria.
If there are risk factors for urological malignancy, request urine cytology, as urothelial carcinoma can result in similar symptoms. A renal tract ultrasound can assist in excluding abnormalities of the renal tract and allow for assessment of the post-void residual volume. A bladder diary is useful in objectively assessing the severity of symptoms, fluid intake, and in excluding nocturnal polyuria.
Box 3 outlines the important differential diagnoses to consider, and exclude, in the workup for potential OAB.
Management options
First line— conservative This involves explaining the diagnosis, along with further treatment options should there be insufficient improvement with initial conservative strategies. Advise on appropriate fluid intake— generally 1.5- 2L water / day, while avoiding fluids for 2-3 hours before sleep to reduce nocturia. Bladder stimulants such as alcohol, caffeine and smoking should be reduced. Weight reduction is recommended for patients with obesity. Constipation warrants proactive management, with an increase in dietary fibre and stool softeners.
Bladder training, with scheduled voiding times and urge control techniques, along with pelvic floor exercises, can be beneficial. This can be optimised through referral to a pelvic floor physiotherapist. Use of incontinence pads rather than regular sanitary pads helps to prevent damage to the vulval skin for those experiencing incontinence. Topical oestrogen reduces urinary urgency, frequency and the number of incontinence episodes for postmenopausal women with OAB. 5
Second line— pharmacotherapy Anticholinergics target the muscarinic receptors, of which M2 and M3 are important for bladder contractility. There is evidence that anticholinergics are more effective than behavioural therapy alone. 6 Typical side effects include dry mouth and constipation, and there is the risk of cognitive side effects in older patients. Multiple recent cohort and case control studies have indicated an association with an increased risk of dementia. 7 It is important to consider other medications that may increase the overall anticholinergic burden when prescribing.
In Australia, the most affordable option is oral oxybutynin; however, this also carries the highest risk of side effects. Given its short half-life, it can be used on an as-needed basis for patients who do not want to use daily medication, or it can be used regularly 2-3 times per day.
Other options include transdermal oxybutynin patches( Oxytrol), which bypass first-pass metabolism. Transdermal delivery reduces side effects; however, 10-15 % of patients experience a skin reaction. 8, 9 Solifenacin( Vesicare) is an anticholinergic that is selective for the M3 receptor subtype, and therefore has reduced side effects. The generic version is now available, which substantially improves affordability, at a cost of $ 16- $ 20 for a month’ s supply.
Beta-3 adrenergic receptor agonists promote detrusor smooth muscle relaxation to reduce bladder spasms. The most common beta-3 agonist used is mirabegron( Betmiga), available in 25mg or 50mg dosing, with a current cost of approximately $ 66 for 30 tablets. The main side effects are hypertension and cardiac arrythmia. Discontinuation rates are lower with beta-3 agonists compared to anticholinergics, and the risk of future cognitive impact also appears to be lower. 2, 10 So far there has been one cohort study suggesting a possible association between dementia and beta-3 agonists; however, this risk was lower risk than with the use of anticholinergics and combined therapy. 10 Some patients will have reduced symptoms with use of combined medical therapy of both an anticholinergic and beta-3 agonist. It is important for all patients to discuss the pros and cons of medications and side effect profiles prior to commencement, as well as to review their ongoing use periodically.
Urodynamic assessment is recommended for patients who have ongoing symptoms despite the above measures. This assessment provides more detailed information and can confirm if there is co-existing stress incontinence, voiding dysfunction, and whether detrusor overactivity is present, and if it is, the severity of it.
Box 1. Contributing factors to OAB
Treatments range from conservative measures such as fluid management and bladder retraining, to medications( anticholinergics and beta-3 agonists, topical oestrogen in postmenopausal women), and third-line therapies such as transcutaneous or percutaneous tibial nerve stimulation, intravesical botulinum toxin and sacral neuromodulation.
Third line— Tibial nerve stimulation Although transcutaneous tibial nerve stimulation( TTNS) is classed as a thirdline treatment, some patients may now elect to trial it before, or in addition to, medication, and often prior to urodynamic testing. This is because of the low risk profile and improved accessibility; and the patient can undertake peripheral nerve stimulation with a TENS machine at home. Stimulation of the posterior tibial nerve is thought to cause activation of the sacral nerve plexus from which it originates, and results in activation of inhibitory neurons causing suppression of detrusor contractions. Small studies have shown similar efficacy with transcutaneous stimulation of the posterior tibial nerve as compared to percutaneous stimulation( PTNS), which is performed in office weekly for 12 weeks,
• Myogenic: detrusor overactivity due to changes within the bladder smooth muscle causing increased excitability and spontaneous contractions.
• Neurogenic: overactivity attributed to increased neuroplasticity within the central nervous system with maladaptive sensory signalling from pelvic nerves.
• Urothelial: chronic urothelial injury can cause increased frequency and decreased voided volumes.
• Urethrogenic( eg, from the urethra): low urethral tone and stress urinary incontinence can stimulate proximal urethral afferent nerves and initiate micturition via urethravesical reflex causing symptoms of OAB.
Box 2. OAB symptoms and severity assessment
• How often the patient needs to void.
• Presence or absence of triggers such as latch-key urgency or the sound of running water.
• Any associated incontinence and the severity of this.
• Presence of voiding issues.
• Presence of co-existing stress urinary incontinence( leakage with cough / sneeze / exercise).
• Presence or absence of nocturia and nocturnal enuresis.