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Source: Rovner ES, Wyman J, Lackner T, Guay DRP. Urinary Incontinence. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. Accessed July 10, 2012.

  • Involuntary leakage of urine

  • Urinary incontinence (UI) occurs as result of overfunctioning or underfunctioning of urethra, bladder, or both.
    • Stress UI (SUI) results from urethral underactivity and occurs during periods of physical activity (e.g., exercise, coughing, and sneezing)
    • Urge UI (UUI) results from bladder overactivity .
      • Associated with increased urinary frequency and urgency, with or without urge incontinence.
    • Overflow incontinence results from urethral overactivity and/or bladder underactivity.
    • Mixed incontinence results from bladder overactivity and urethral underactivity.
  • Functional incontinence linked to primary disease process such as dementia or cognitive or mobility deficits.
  • Many medications can aggravate voiding dysfunction and UI (Table 1).

Table 1. Medications that Influence Lower Urinary Tract Function

  • Urethral sphincter maintains adequate resistance to flow of urine from bladder until voluntary voiding initiated.
  • Normal bladder emptying occurs with opening of urethra concomitant with volitional bladder contraction.
    • Acetylcholine activates postsynaptic muscarinic receptors that mediate both volitional and involuntary contractions of bladder.
      • M3 receptors responsible for both emptying contraction of normal micturition and involuntary bladder contractions, which can result in urinary incontinence (UI).
      • Most pharmacologic antimuscarinic therapy anti-M3 based.

  • True prevalence difficult to determine.
  • Peak incidence in women at time of menopause.

  • Idiopathic bladder contractions that cause leakage in elderly
  • Urinary tract infection (UTI)
  • Vaginitis
  • Transient increased urinary output caused by
    • Hyperglycemia
    • Diuretics
    • Excess fluid intake

  • Signs and symptoms of UI depend on underlying pathophysiology (Table 2)

Table 2. Differentiating Bladder Overactivity from Urethral Underactivity

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