Overactive bladder (OAB) is defined as “urinary urgency, usually with urinary frequency and nocturia, with or without urgency urinary incontinence (UUI), in the absence of UTI or other obvious pathology”. The prevalence in adults aged over 18 is 10.8% in men and 12.8% in women. UUI is the most bothersome symptom.
History should include sexual, gastrointestinal and neurological symptoms. Perform an abdominal and pelvic examination checking for: vaginal atrophy, pelvic floor muscle weakness, prolapse and leakage with cough in females; phimosis, meatal stenosis, and prostate enlargement in males.
Spine tenderness or deformity, decreased perianal sensation, lax or tight anal sphincter tone and lower limb weakness or paraesthesia suggest underlying neurological disease. Use bladder diaries and pad weights to evaluate the types and volumes of fluids consumed, number of voids, volumes voided and the degree of leakage. Useful investigations are UEC, HbA1c, urine MCS and urinary tract ultrasound.
Comorbidities that can aggravate the condition include cardiac failure, diabetes mellitus, sleep disturbances (e.g. OSA, restless legs) and neurological conditions (e.g. MS, Parkinson’s, stroke). Medications such as diuretics and beta blockers may also exacerbate symptoms.
Behavioural and lifestyle changes are first-line management and can be initiated by general practitioners. Restrict evening fluids and consumption of bladder irritants or diuretics (caffeine, alcohol, acidic and spicy food). Increase fibre intake to prevent constipation.
A 5-10% weight loss substantially improves continence, though evidence base relates to stress rather than urge leakage. Pelvic floor muscle exercises and bladder retraining help to stabilise the proximal urethra, improve urethral function and increase the inhibition of urgency, detrusor contractions and incontinence.
Anticholinergics reduce detrusor smooth muscle contractility and involuntary spasms, resulting in one less micturition per 48 hours, one less leakage episode per 48 hours and average 54ml increase in maximum bladder volume in medication vs placebo group.
Interestingly, there is a striking placebo effect, with cure or improvement reported in 60% medication vs 45% placebo groups. Dry mouth is the most common and bothersome adverse effect, with high discontinuation rates.
Current evidence suggests that no anticholinergic drug is clearly superior to another. Transdermal oxybutynin has lower rates of adverse effects and can be prescribed as a PBS Restricted item if the patient cannot tolerate oral oxybutynin. Solifenacin and darifenacin did not appear to worsen cognitive impairment short term.
It is best to avoid using anticholinergics in the elderly patient due to association with increased dementia incidence and cognitive decline. When other alternatives are inappropriate or ineffective, the risks and benefits should be clearly discussed, lowest effective dosage used, and clear time frames set for proposed duration of treatment with regular cognitive assessment.
Mirabegron relaxes detrusor muscle and increases bladder capacity. It is a useful first-line drug in elderly patients as it does not impair cognition, and males who often have bladder emptying problems due to prostate enlargement. Efficacy is modest, with reduction of incontinence episodes of 1.5 a day vs placebo 1.1. Blood pressure monitoring is recommended due to risk of hypertension (7.3%). Caution is advised in patients with prolonged QT interval or taking drugs metabolised by CYP2D6 (e.g., flecainide imipramine).
Urological referral
This should be considered in these situations.
- Persistent microhaematuria or painless macrohaematuria
- Recurrent UTIs, renal decline or obstructive uropathy
- Risk factors for urological malignancy
- New persistent symptoms without explanation or obvious cause
- Severe symptoms refractory to first-line treatment
Flexible cystoscopy with or without urodynamic studies are usually performed to exclude bladder pathology and assess the type and severity of voiding dysfunction prior to intervention.
Posterior tibial nerve stimulation (PTNS) delivers electrical impulses to the sacral plexus through an acupuncture needle inserted in the ankle near the posterior tibial nerve. Studies show significant improvement in frequency, urgency, nocturia, incontinence, maximum cystometric capacity and compliance.
Induction phase includes 12 weekly sessions in the first three months. Tapering phase is five sessions over the next three months. Maintenance phase is one session monthly ongoing. Adverse effects are rare, apart from minor discomfort at needle site. PTNS offers a low-risk option but is laborious with poor compliance rates.
Intravesical botulinum toxin injections are administered cystoscopically under local or general anaesthetia every 3-15 months (median 7.5). Efficacy is superior to pharmacotherapy, with urge incontinence episodes per day reduced by half, frequency decreased by >2 times and 23% of patients fully dry. Patients have consistent or increasing duration of effect with subsequent treatments. Increased post-void residuals in the first few weeks is common.
Sacral Neuromodulation (SNM) delivers low-amplitude electrical impulses to the sacral nerve roots from an MRI-compatible pulse generator implanted in the gluteal region. Half of patients with UUI demonstrated >90% reduction in leakage episodes, with continued success at four years and cure rates of 15%.
When compared over two years, SNM and botulinum toxin injections are equally effective.
Experimental laser treatment and acupuncture are two other modalities advertised and used in OAB management. However, the quality of evidence remains low and are not generally recommended.
– References available on request
Author competing interests – nil