What is overactive bladder?

Overactive Bladder (OAB)

Overactive bladder (OAB) is a clinical syndrome characterized by urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence (UUI), in the absence of urinary tract infection or other obvious pathology. 1

Definition and Key Symptoms

• Urgency is the hallmark symptom of OAB, defined as "the complaint of a sudden, compelling desire to pass urine which is difficult to defer" 1
• Urinary frequency is commonly present, traditionally defined as more than seven micturition episodes during waking hours, though this varies based on sleep patterns, fluid intake, and comorbidities 1
• Nocturia, defined as interruption of sleep one or more times because of the need to void, is often present 1
• Urgency urinary incontinence (UUI) may or may not be present, defined as involuntary leakage of urine associated with a sudden compelling desire to void 1

Diagnostic Considerations

• OAB is a diagnosis of exclusion requiring careful history, physical examination, and urinalysis to rule out other conditions 1
• When both daytime and nighttime urinary frequency and urgency (with or without urgency incontinence) are self-reported as bothersome, the patient may be diagnosed with OAB 1
• Urinary frequency in OAB is typically characterized by many small volume voids, distinguishing it from conditions like polydipsia 1
• A voiding diary is a reliable tool to measure urinary frequency and incontinence episodes 1

Differential Diagnosis

• OAB must be distinguished from:
  • Urinary tract infection (requires urinalysis to exclude) 1
  • Nocturnal polyuria (characterized by normal or large volume nocturnal voids, unlike the small volume voids in OAB) 1
  • Overflow incontinence (characterized by elevated post-void residual volumes >250-300 mL) 2
  • Interstitial cystitis/bladder pain syndrome (characterized by pain as the primary symptom) 3
  • Neurogenic bladder dysfunction (requires specialized evaluation) 3

Clinical Impact

• OAB affects approximately 17% of the population in the United States and Europe 4
• Patients often suffer with symptoms for an extended time before seeking medical advice 1
• OAB significantly impacts quality of life and is not a normal consequence of aging 4, 5

Management Approach

• Initial management requires an integrated approach using behavioral and pharmacologic methods 6, 7
• First-line treatment includes:
  • Patient education about normal lower urinary tract function 8, 7
  • Fluid and dietary management 6, 7
  • Timed or prophylactic voiding and bladder training regimens 6, 5
  • Pelvic floor exercises 7, 5
• Pharmacologic options include:
  • Antimuscarinic medications (e.g., tolterodine, oxybutynin) 8, 4
  • Beta-3 adrenergic receptor agonists (e.g., mirabegron) 9, 5
• Refractory cases may require specialist referral for consideration of:
  • Botulinum toxin A injections 7, 5
  • Neuromodulation techniques (sacral nerve stimulation, tibial nerve stimulation) 6, 5
  • Rarely, augmentation cystoplasty in extreme cases 6, 5

Common Pitfalls

• Misdiagnosing overflow incontinence as OAB can lead to inappropriate treatment with antimuscarinics, potentially worsening retention 2, 3
• Failure to distinguish between mixed urinary incontinence (both stress and urgency) and pure OAB 1
• Not considering medication side effects as potential contributors to urinary symptoms 2, 8
• Inadequate follow-up to assess treatment efficacy and manage adverse events 1