Medical Health Encyclopedia

Urinary incontinence

The first sensation of the urge to urinate occurs when approximately 200 ml (just under 1 cup) of urine is stored. A healthy nervous system will respond to this stretching sensation by alerting you to the urge to urinate, while also allowing the bladder to continue to fill.

The average person can hold approximately 350 to 550 ml (over 2 cups) of urine. The ability to fill and store urine properly requires a functional sphincter (the circular muscles around the opening of the bladder) and a stable, expandable bladder wall muscle (detrusor).

The emptying phase requires the ability of the detrusor muscle to appropriately contract to force urine out of the bladder. At the same time, your body must be able to relax the sphincter to allow the urine to pass out of the body.

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Common Causes:

Incontinence may be sudden and temporary, or ongoing and long-term. Causes of sudden or temporary incontinence include:

• Urinary tract infection or inflammation
• Prostate infection or inflammation
• Stool impaction from severe constipation, causing pressure on the bladder
• Side effects of medications (such as diuretics, tranquilizers, some cough and cold remedies, certain antihistamines for allergies, and antidepressants)
• Increased urine amounts, like with poorly controlled diabetes
• Pregnancy
• Weight gain
• Short-term bedrest -- for example, when recovering from surgery
• Mental confusion

Causes that may be more long-term:

• Spinal injuries
• Urinary tract anatomical abnormalities
• Neurological conditions like multiple sclerosis or stroke
• Weakness of the sphincter, the circular muscles of the bladder responsible for opening and closing it; this can happen following prostate surgery in men, or vaginal surgery in women
• Pelvic prolapse in women -- falling or sliding of the bladder, urethra, or rectum into the vaginal space, often related to having had multiple pregnancies and deliveries
• Large prostate in men
• Depression or Alzheimer's disease
• Nerve or muscle damage after pelvic radiation
• Bladder cancer
• Bladder spasms