Causes and Symptoms
Aging itself does not cause urinary incontinence, but changes that occur with aging can increase the risk of developing urinary incontinence by interfering with a person’s ability to control urination. For example, the maximum amount of urine that the bladder can hold (bladder capacity) decreases. The ability to postpone urination decreases. More urine remains in the bladder after urination (residual urine), partly due to less effective squeezing of the bladder muscle. In postmenopausal women, the urinary sphincter does not hold back urine in the bladder as effectively because of the decrease in estrogen levels after menopause leads to shortening of the urethra and thinning and fragility (atrophy) of its lining. Also, urine flow through the urethra slows. In men, urine flow through the urethra may be impeded by an enlarged prostate gland, eventually leading to bladder enlargement.
Urinary incontinence has many possible causes. Some causes, such as a bladder infection, a broken hip, or delirium, can bring on incontinence suddenly and abruptly. Other causes, such as an enlarged prostate in men or dementia, gradually interfere with control of urination until incontinence results. Incontinence may resolve and never recur. Alternatively, it may persist recurring sporadically or in some cases, frequently.
Many experts try to categorize incontinence according to the basic cause of the problem. The categories or types that most experts agree on are as follows:
Urge incontinence: Urge incontinence is an abrupt and intense urge to urinate that cannot be suppressed, followed by an uncontrollable loss of urine. The amount of urine lost may be small or large. People with urge incontinence usually have very little time to get to the toilet before they have an “accident.” Most people with urge incontinence urinate more frequently, not only during the day but also at night (nocturia). Urge incontinence is the most common type of persistent incontinence in older people.
Stress incontinence: Stress incontinence is the uncontrollable loss of small amounts of urine when coughing, straining, sneezing or lifting heavy objects or during any activity that suddenly increases pressure within the abdomen. This increased pressure overcomes the resistance of the closed urinary sphincter. Urine then flows into and through the urethra. Stress incontinence is common in women but uncommon in men.
Any condition or event that weakens and reduces resistance of the urinary sphincter or urethra can cause stress incontinence. Childbirth for example, can weaken the urinary sphincter, as can surgery involving organs or structures in the pelvis, such as the uterus (for example, hysterectomy). In men, stress incontinence may follow prostate surgery if the urinary sphincter is injured. In both men and women, obesity can cause or worsen stress incontinence as extra weight adds additional pressure on the bladder.
Overflow incontinence: Overflow incontinence is the uncontrollable leakage of small amounts of urine, usually caused by some type of blockage or by weak contractions of the bladder muscle. This causes urine in the bladder to be retained (urinary retention) and the bladder enlarges. Pressure in the bladder continues to increase until small amounts of urine dribble out. The increased pressure in the bladder can also damage the kidneys.
In older men, an enlarged prostate can block the urethra. Less commonly, scar tissue narrows or sometimes even blocks the lowest part of the bladder, where it connects to the urethra or blocks the urethra itself (urethral stricture). Such narrowing or blockage may occur after prostate surgery. In men
and women, severe constipation or stool impaction can cause overflow incontinence. Nerve damage that paralyzes the bladder (a condition commonly called neurogenic bladder) can also cause overflow incontinence. Stroke and diabetes mellitus can paralyze the bladder, leading to overflow incontinence.
Functional incontinence: Functional incontinence refers to urine loss resulting from the inability to get to a toilet. The most common causes are conditions that lead to immobility, such as stroke or severe arthritis and conditions that interfere with mental function, such as dementia due to Alzheimer’s disease. In rare cases, people become so depressed that they do not go to the toilet (psychogenic incontinence).
Mixed incontinence: Mixed incontinence involves more than one type of incontinence. The most common type of mixed incontinence occurs in older women, who often have a mixture of urge and stress incontinence.