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Causes Of Urinary Incontinence
By peace | October 4, 2006
Bladder function can be thought of in two phases: filling and storage of urine, and emptying (voiding).
In filling, the urethra is squeezed shut while the bladder itself is relaxed, expanding as it fills with urine. In voiding, the urethra relaxes just before a contraction of the detrusor muscle in the bladder wall. The urine is then pushed through the urethra to the outside.
How often you pass urine is dependent on how much urine is produced as well as how much urine the bladder will hold. If you drink 1.5 litres a day and your bladder normally holds 400 millilitres (ml), then you will empty your bladder approximately four times that day. A bladder that holds only 100 ml results in passing urine fifteen times. If you drink twice as much, then you will need to empty your bladder twice as frequently. Normal frequency of voiding is up to seven times a day or not more than every two hours. In young women, the bladder normally holds 400–600 ml and is usually emptied when holding 250–400 ml. As people age, their bladder capacity tends to decrease, leading to increased frequency of micturition (voiding), especially at night.
Urinary Incontinence in Women
Urinary incontinence is an inability to hold your urine until you get to a toilet. More than 13 million people in the United States—male and female, young and old—experience incontinence. It is often temporary, and it always results from an underlying medical condition.
Women experience incontinence twice as often as men. Pregnancy and childbirth, menopause, and the structure of the female urinary tract account for this difference. But both women and men can become incontinent from neurologic injury, birth defects, strokes, multiple sclerosis, and physical problems associated with aging.
Older women, more often than younger women, experience incontinence. But incontinence is not inevitable with age. Incontinence is treatable and often curable at all ages.
Incontinence in women usually occurs because of problems with muscles that help to hold or release urine. The body stores urine—water and wastes removed by the kidneys—in the bladder, a balloon-like organ. The bladder connects to the urethra, the tube through which urine leaves the body.
During urination, muscles in the wall of the bladder contract, forcing urine out of the bladder and into the urethra. At the same time, sphincter muscles surrounding the urethra relax, letting urine pass out of the body. Incontinence will occur if your bladder muscles suddenly contract or muscles surrounding the urethra suddenly relax.
Urinary incontinence isn’t a disease itself. It indicates some underlying problem or condition that likely can and should be treated. A thorough evaluation by your doctor can help determine what’s behind your incontinence.
How your urinary system works
Your urinary tract collects, stores and eliminates urine from your body. When you eat and drink, your body absorbs liquid. Excess fluid and liquid waste accumulate in your bloodstream. Your kidneys — a pair of bean-shaped organs — filter your blood, removing liquid waste to make urine.
From your kidneys, urine travels down a pair of long tubes called ureters and empties into your bladder — a muscular, balloon-like sac that stores urine. Connected to the bottom (neck) of your bladder is a short tube called the urethra. Urine exits your body through the urethra. In women, the urethral opening is located just above the vagina. In men, the urethral opening is at the tip of the penis.
When you urinate, several things happen. First the pelvic floor muscles relax, allowing urine to pass out of your body easily. Then your bladder muscle (detrusor muscle) contracts, pushing urine out of your bladder and through the urethra. Between episodes of urination, your bladder muscle relaxes, allowing urine to be stored in your bladder. At the same time, the pelvic floor muscles lightly contract, holding the urine in the bladder and supporting your bladder from underneath.
Nerves that run from your spinal cord to your bladder coordinate the action of these muscles. When you feel the urge to urinate, nerves in your bladder have sent a signal to your brain that your bladder is full. Your brain is responsible for keeping your bladder from contracting without your permission. But certain neurological conditions such as Alzheimer’s or stroke may impair the brain’s ability to keep the bladder from firing and causing leakage.
The bottom line is that good bladder control isn’t simple. As a child, you learn how to hold on until you get to the bathroom. But urination is a complex process that involves relaxing part of the pelvis while contracting another part. The many organs, tubes, muscles and nerves in your urinary system must work together. If any part malfunctions, incontinence can result.
Causes of temporary urinary incontinence
Urinary incontinence has many possible causes. Some causes are temporary and can be managed with simple treatment. Examples include:
- Consuming alcohol to excess. Alcohol is a diuretic. It causes your bladder to fill quickly, triggering an urgent and sometimes uncontrollable need to urinate. In addition, alcohol can temporarily impair your ability to recognize the need to urinate and act on that need in a timely manner.
- Drinking a lot of fluid. Drinking a lot of water or other beverages, particularly in a short period of time, increases the amount of urine your bladder has to deal with and may result in an occasional accident.
- Not drinking enough fluid. If you have urge incontinence, you may try to limit your fluids to reduce the number of trips to the toilet. However, if you don’t consume enough liquid to stay hydrated, your urine can occasionally become very concentrated. This collection of concentrated salts can irritate your bladder and worsen your urge incontinence.
- Overdoing the caffeine. Caffeine also is a diuretic. It causes your bladder to fill more quickly than usual so that you suddenly and perhaps uncontrollably need to urinate.
- Consuming foods and beverages that irritate your bladder. Carbonated drinks, tea and coffee — with or without caffeine — may irritate your bladder and cause episodes of urge incontinence. Citrus fruits and juices and artificial sweeteners also can be sources of aggravation.
- Taking certain medications. Sedatives, such as sleeping pills, can sometimes interfere with your ability to control bladder function. Other medications — including water pills (diuretics), muscle relaxants and antidepressants — can cause or increase incontinence. Some high blood pressure drugs, heart medications and cold medicines also can affect bladder function. After surgery, some people experience temporary overflow incontinence from the lingering effects of anesthesia.
- Urinary tract infection. This very common condition can cause bladder irritation and even incontinence. This infection involves your urinary tract, usually your bladder — in which case it’s called a bladder infection (cystitis). Germs from the outside enter your urethra and bladder, then start to multiply. The resulting infection irritates your bladder, causing you to experience strong urges to urinate. These urges may result in episodes of incontinence, which may be your only warning sign of a urinary tract infection. Other possible signs and symptoms include a burning sensation when you urinate and foul-smelling urine.
- Constipation. The rectum is located near the bladder and shares many of the same nerves. Hard, compacted stool in your rectum causes these nerves to be overactive, causing you to leak urine.
Causes of persistent urinary incontinence
More often, urinary incontinence is a persistent condition caused by some underlying physical problem — weakened muscles, nerve problems or an obstruction in your urinary tract. Factors that can lead to chronic incontinence include:
- Pregnancy and childbirth. Pregnant women may experience stress incontinence because of hormonal changes and the increased weight of an enlarging uterus. In addition, the stress of childbirth can weaken the pelvic floor muscles and the ring of muscles that surrounds the urethra (urinary sphincter). The result is often stress incontinence — urine escapes past the weakened muscles whenever pressure is placed on your bladder. The stress of childbearing also can damage bladder nerves or lead to a dropped (prolapsed) bladder — a cystocele. With a cystocele, your bladder gets pushed out of its usual position and protrudes into your vagina. Signs and symptoms include the feeling of a protrusion in your vagina and often incontinence. Incontinence related to childbirth may develop right after delivery or may not develop until many years later.
- Hormonal changes following menopause. After menopause, a woman’s body produces less of the hormone estrogen. This drop in estrogen can contribute to incontinence. In women, estrogen helps keep the lining of the bladder and urethra healthy. With less estrogen, these tissues lose some of their ability to close — meaning that your urethra can’t hold back urine as easily as before. Meanwhile, aging of the bladder muscle affects both men and women, leading to a decrease in the bladder’s capacity to store urine.
- Hysterectomy. In women, the bladder and uterus (womb) lie close to one another and are supported by the same muscles and ligaments. Any surgery that involves a woman’s reproductive system — for example, removal of the uterus (hysterectomy) — runs the risk of damaging muscles or nerves of the urinary tract, which can lead to incontinence.
- Interstitial cystitis. This inflammation of the bladder wall is a cause of painful and frequent urination, and sometimes incontinence. This chronic condition usually affects women more often than men. Its cause isn’t clear.
- Prostatitis. In rare cases, this common condition in men can cause incontinence. Prostatitis is inflammation of the prostate gland — an organ about the size and shape of a walnut located just below the bladder. The prostate, which produces seminal fluid, actually surrounds the urethra. If it becomes infected or inflamed, it can occasionally swell and constrict the urethra. This can block normal urine flow, leading to urinary urgency and frequency. Rarely, this also causes incontinence.
- Enlarged prostate. In older men, incontinence often stems not from irritation but from enlargement of the prostate gland, a condition also known as benign prostatic hyperplasia (BPH). Around age 40 in men, the prostate begins to enlarge slightly. As the gland enlarges, it can constrict the urethra and block the flow of urine. For some men, this problem results in urge or overflow incontinence.
- Prostate cancer. In men, incontinence can be associated with untreated prostate cancer. However, more often, incontinence is a side effect of treatments — surgery or radiation — for prostate cancer.
- Bladder cancer. Incontinence, urinary urgency and burning with urination can be signs and symptoms of bladder cancer. Other signs and symptoms of bladder cancer include blood in the urine and pelvic pain.
- Neurological disorders. Multiple sclerosis, Parkinson’s disease, stroke, a brain tumor or a spinal cord injury can damage the nerves of your bladder, your nervous system and muscles.
- Obstruction. A tumor anywhere along your urinary tract can obstruct the normal flow of urine and cause incontinence, usually overflow incontinence. Urinary stones — hard, stone-like masses that can form in the bladder — may be to blame for urine leakage.
- Other illnesses or injuries. Any illness, injury or disability that keeps you from getting to the toilet in time also is a potential cause of incontinence.
Causes of urinary incontinence in children
In children, urinary incontinence may have several causes. Children who wet the bed at night may be slower to develop the brain control needed to allow storage of urine all night. These children may also produce more urine at night or their brains may lack the ability to recognize that the bladder is overfilled when they’re asleep. Most children outgrow nighttime incontinence. Children who experience daytime incontinence should undergo evaluation, as they may have a urinary tract infection or a developmental abnormality. Some children simply may hold their urine longer than they should.
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