Urinary Incontinence for ABIM
Urinary Incontinence for the American Board of Internal Medicine Exam
- Definition:
- Urinary incontinence is the involuntary leakage of urine. It can be classified into several types based on the underlying pathophysiology: stress incontinence, urge incontinence, overflow incontinence, and functional incontinence. Mixed incontinence refers to the presence of more than one type.
- Types of Urinary Incontinence:
- Stress Incontinence:
- Stress incontinence occurs when intra-abdominal pressure (e.g., during coughing, sneezing, or laughing) exceeds urethral sphincter resistance, resulting in urine leakage.
- Pathophysiology:
- Common in women, stress incontinence is often due to weakness of the pelvic floor muscles or urethral sphincter incompetence. It is frequently associated with childbirth, obesity, and aging. In men, stress incontinence can occur after prostate surgery.
- Risk Factors:
- Pregnancy, vaginal delivery, menopause (decreased estrogen weakens pelvic muscles), pelvic surgery, and conditions that increase intra-abdominal pressure (obesity, chronic coughing).
- Urge Incontinence (Overactive Bladder):
- Urge incontinence is characterized by a sudden, intense urge to urinate followed by involuntary urine loss.
- Pathophysiology:
- Urge incontinence is due to detrusor overactivity, where the bladder muscle contracts inappropriately. It can occur in neurological disorders (e.g., Parkinson’s disease, multiple sclerosis, stroke) or without an identifiable cause (idiopathic). Aging, bladder outlet obstruction, and urinary tract infections can also contribute.
- Symptoms:
- Patients experience frequent urination, nocturia, and an urgent need to void, often leading to leakage before reaching the toilet.
- Overflow Incontinence:
- Overflow incontinence results from incomplete bladder emptying, leading to frequent or continuous dribbling of urine.
- Pathophysiology:
- This occurs when the bladder is overdistended due to a blockage (e.g., benign prostatic hyperplasia [BPH], urethral stricture) or poor detrusor muscle function (e.g., diabetic neuropathy). The bladder fails to empty properly, causing small amounts of urine to leak.
- Risk Factors:
- Men with BPH, spinal cord injuries, or conditions causing neurogenic bladder.
- Functional Incontinence:
- Functional incontinence occurs when the patient is unable to reach the toilet due to physical or cognitive impairments, despite having normal bladder control.
- Risk Factors:
- Dementia, severe arthritis, mobility disorders, or postoperative immobility.
- Mixed Incontinence:
- Mixed incontinence is a combination of stress and urge incontinence, often seen in older women.
- Epidemiology:
- Urinary incontinence is more common in women than men, with increasing prevalence with age. Postmenopausal women and elderly individuals are particularly affected. It can significantly impact quality of life, leading to social isolation, depression, and reduced physical activity.
- Evaluation:
- History and Physical Examination:
- A thorough medical history should focus on the onset, frequency, severity, and circumstances of urine leakage. Key questions include whether leakage occurs with coughing, urgency, or continuously.
- Review any comorbid conditions (e.g., diabetes, neurological disorders) and current medications (e.g., diuretics, alpha-blockers, anticholinergics) that may contribute to symptoms.
- Perform a pelvic examination in women to assess for pelvic organ prolapse or atrophic vaginitis. In men, a digital rectal examination (DRE) is indicated to evaluate prostate size in cases of suspected BPH.
- Diagnostic Testing:
- Urinalysis: Helps rule out infection, hematuria, or other underlying pathology like bladder cancer.
- Postvoid Residual (PVR) Volume: Measured by ultrasound or catheterization to assess bladder emptying. High residual volumes suggest overflow incontinence or bladder outlet obstruction.
- Bladder Diary: A bladder diary kept by the patient records voiding times, fluid intake, leakage episodes, and associated activities. It helps distinguish between different types of incontinence.
- Urodynamic Studies: Used for complex cases, these tests measure bladder function, including detrusor activity, bladder capacity, and urethral sphincter function. Urodynamics are helpful in distinguishing stress from urge incontinence and identifying detrusor overactivity.
- Management:
- Lifestyle and Behavioral Interventions:
- Pelvic Floor Muscle Training (Kegel Exercises):
- First-line treatment for stress incontinence, pelvic floor exercises strengthen the muscles supporting the bladder and urethra. Biofeedback may enhance effectiveness.
- Bladder Training:
- Recommended for urge incontinence, bladder training involves teaching patients to gradually extend the time between voids and resist urgency. It may be combined with timed voiding schedules.
- Fluid and Diet Management:
- Reducing fluid intake, especially before bedtime, and avoiding bladder irritants like caffeine, alcohol, and acidic foods can help in managing symptoms.
- Weight Loss:
- For overweight or obese patients, weight loss reduces intra-abdominal pressure and improves stress incontinence.
- Pharmacologic Therapy:
- Anticholinergics (e.g., oxybutynin, tolterodine):
- These agents are the first-line pharmacologic treatment for urge incontinence. They reduce detrusor overactivity but have side effects such as dry mouth, constipation, and blurred vision.
- Beta-3 Agonists (e.g., mirabegron):
- An alternative for patients who cannot tolerate anticholinergics, mirabegron relaxes the bladder muscle and increases storage capacity.
- Topical Estrogens:
- For postmenopausal women with stress incontinence, local estrogen therapy can improve urethral sphincter tone and vaginal atrophy, though systemic estrogen is not recommended due to cardiovascular risks.
- Alpha Blockers (e.g., tamsulosin):
- Used in men with overflow incontinence due to BPH, alpha-blockers relax the smooth muscle of the prostate and bladder neck, improving urinary flow.
- 5-Alpha Reductase Inhibitors (e.g., finasteride):
- Also used in BPH to reduce prostate size and prevent progression of obstruction.
- Surgical Interventions:
- Midurethral Sling Procedures:
- The most common surgery for stress incontinence in women, involving the placement of a sling under the urethra to support it and prevent leakage during increased intra-abdominal pressure.
- Artificial Urinary Sphincter:
- For men with stress incontinence, particularly post-prostatectomy, this device provides mechanical urethral compression to prevent leakage.
- Prostate Surgery:
- In men with BPH and overflow incontinence, transurethral resection of the prostate (TURP) can relieve bladder outlet obstruction and improve symptoms.
- Invasive Therapies for Urge Incontinence:
- Botulinum Toxin Injections:
- Used in patients with refractory detrusor overactivity, botulinum toxin injections relax the bladder muscle and reduce urge incontinence.
- Sacral Nerve Stimulation:
- A surgically implanted device that modulates nerve signals to the bladder and improves control in severe urge incontinence.
- Prognosis:
- Most patients with urinary incontinence improve with lifestyle modifications, behavioral therapy, and pharmacologic interventions. Surgical procedures are highly effective in carefully selected patients with stress or overflow incontinence. Ongoing management is crucial to maintain quality of life and prevent complications such as skin breakdown, infections, and social isolation.
Key Points
- Urinary incontinence is a common condition that can be classified into stress, urge, overflow, and functional types based on pathophysiology.
- Diagnosis involves a thorough history, physical exam, urinalysis, and postvoid residual measurements. Urodynamic studies may be needed in complex cases.
- Treatment begins with conservative measures like pelvic floor exercises and bladder training. Pharmacologic therapy (anticholinergics, beta-3 agonists, alpha-blockers) is used for urge or overflow incontinence.
- Surgical options, including sling procedures and prostate surgery, are effective for stress and overflow incontinence.
- Successful management improves patient quality of life and reduces the risk of complications associated with urinary incontinence.