How Does the Urinary System Work
Urination, or voiding, is a complex activity. The bladder is a balloon-like muscle that lies in the lowest part of the abdomen. The bladder stores urine, then releases it through the urethra, the canal that carries urine to the outside of the body. Controlling this activity involves nerves, muscles, the spinal cord, and the brain.

The bladder is made of two types of muscles: the detrusor, a muscular sac that stores urine and squeezes to empty, and the sphincter, a circular group of muscles at the bottom or neck of the bladder that automatically stay contracted to hold the urine in and automatically relax when the detrusor contracts to let the urine into the urethra. A third group of muscles below the bladder (pelvic floor muscles) can contract to keep urine back.

A baby's bladder fills to a set point, then automatically contracts and empties. As the child gets older, the nervous system develops. The child's brain begins to get messages from the filling bladder and begins to send messages to the bladder to keep it from automatically emptying until the child decides it is the time and place to void.

Failures in this control mechanism result in incontinence. Reasons for this failure range from the simple to the complex. Incontinence happens less often after age 5: About 10 percent of 5-year-olds, 5 percent of 10-year-olds, and 1 percent of 18-year-olds experience episodes of incontinence. It is twice as common in boys as in girls.

What Causes Nighttime Incontinence?
After age 5, wetting at night--often called bedwetting or sleepwetting--is more common than daytime wetting in boys. Experts do not know what causes nighttime incontinence. Young people who experience nighttime wetting tend to be physically and emotionally normal. Most cases probably result from a mix of factors including slower physical development, an overproduction of urine at night, a lack of ability to recognize bladder filling when asleep, and, in some cases, anxiety. For many, there is a strong family history of bedwetting, suggesting an inherited factor.

Slower Physical Development
Between the ages of 5 and 10, incontinence may be the result of a small bladder capacity, long sleeping periods, and underdevelopment of the body's alarms that signal a full or emptying bladder. This form of incontinence will fade away as the bladder grows and the natural alarms become operational.

Excessive Output of Urine During Sleep
Normally, the body produces a hormone that can slow the making of urine. This hormone is called antidiuretic hormone, or ADH. The body normally produces more ADH at night so that the need to urinate is lower. If the body doesn't produce enough ADH at night, the making of urine may not be slowed down, leading to bladder overfilling. If a child does not sense the bladder filling and awaken to urinate, then wetting will occur.

Anxiety
Experts suggest that anxiety-causing events occurring in the lives of children ages 2 to 4 might lead to incontinence before the child achieves total bladder control. Anxiety experienced after age 4 might lead to wetting after the child has been dry for a period of 6 months or more. Such events include angry parents, unfamiliar social situations, and overwhelming family events such as the birth of a brother or sister.

Incontinence itself is an anxiety-causing event. Strong bladder contractions leading to leakage in the daytime can cause embarrassment and anxiety that lead to wetting at night.

Genetics
Certain inherited genes appear to contribute to incontinence. In 1995, Danish researchers announced they had found a site on human chromosome 13 that is responsible, at least in part, for nighttime wetting. If both parents were bedwetters, a child has an 80 percent chance of being a bedwetter also. Experts believe that other, undetermined genes also may be involved in incontinence.

Structural Problems
Finally, a small number of cases of incontinence are caused by physical problems in the urinary system in children. Rarely, a blocked bladder or urethra may cause the bladder to overfill and leak. Nerve damage associated with the birth defect spina bifida can cause incontinence. In these cases, the incontinence can appear as a constant dribbling of urine.

What Causes Daytime Incontinence?
Daytime incontinence that is not associated with urinary infection or anatomic abnormalities is less common than nighttime incontinence and tends to disappear much earlier than the nighttime versions. One possible cause of daytime incontinence is an overactive bladder. Many children with daytime incontinence have abnormal voiding habits, the most common being infrequent voiding.

An Overactive Bladder
Muscles surrounding the urethra (the tube that takes urine away from the bladder) have the job of keeping the passage closed, preventing urine from passing out of the body. If the bladder contracts strongly and without warning, the muscles surrounding the urethra may not be able to keep urine from passing. This often happens as a consequence of urinary tract infection and is more common in girls.

Infrequent Voiding
Infrequent voiding refers to a child's voluntarily holding urine for prolonged intervals. For example, a child may not want to use the toilets at school or may not want to interrupt enjoyable activities, so he or she ignores the body's signal of a full bladder. In these cases, the bladder can overfill and leak urine. Additionally, these children often develop urinary tract infections (UTIs), leading to an irritable or overactive bladder.

Other Causes
Some of the same factors that contribute to nighttime incontinence may act together with infrequent voiding to produce daytime incontinence. These factors include

• A small bladder capacity
• Structural problems
• Anxiety-causing events
• Pressure from a hard bowel movement (constipation)
• Ingestion of bladder irritants such as caffeine and aspartame (an artificial sweetener).

Sometimes overly strenuous toilet training may make the child unable to relax the sphincter and the pelvic floor to completely empty the bladder. Retaining urine (incomplete emptying) sets the stage for urinary tract infections.

Medications
Nighttime incontinence may be treated by increasing ADH levels. The hormone can be boosted by a synthetic version known as desmopressin, or DDAVP. Users, including children, spray a mist containing desmopressin into their nostrils, where the drug enters the bloodstream. Researchers are developing a pill version of this drug.

Another medication, called imipramine, is also used to treat sleepwetting. It acts on both the brain and the urinary bladder. Unfortunately, total dryness with either of the medications available is achieved in only about 20 percent of patients. If a young person experiences incontinence resulting from an overactive bladder, a doctor might prescribe a medicine that helps to calm the bladder muscle. This medicine controls muscle spasms and belongs to a class of medications called anticholinergics.

Bladder Training and Related Strategies
Bladder training consists of exercises for strengthening and coordinating muscles of the bladder and urethra, and may help the control of urination. These techniques teach the child to anticipate the need to urinate and prevent urination when away from a toilet. Techniques that may help nighttime incontinence include

• Determining bladder capacity
• Stretching the bladder (delaying urinating)
• Drinking less fluid before sleeping
• Developing routines for waking up.

Unfortunately, none of the above has demonstrated proven success. Techniques that may help daytime incontinence include

• Urinating on a schedule, such as every 2 hours (this is called timed voiding)
• Avoiding caffeine and the artificial sweetener aspartame
• Following suggestions for healthy urination, such as relaxing muscles and taking your time.

Moisture Alarms
At night, moisture alarms can wake a person when he or she begins to urinate. These devices include a water-sensitive pad worn in pajamas, a wire connecting to a battery driven control, and an alarm that sounds when moisture is first detected. For the alarm to be effective, the child must awaken or be awakened as soon as the alarm goes off. This may require having another person sleep in the same room to awaken the bedwetter.

Incontinence is also called enuresis
Primary enuresis refers to wetting in a person who has never been dry for at least 6 months.
Secondary enuresis refers to wetting that begins after at least 6 months of dryness.
Nocturnal enuresis refers to wetting that usually occurs during sleep (nighttime incontinence).
Diurnal enuresis refers to wetting when awake (daytime incontinence). Points to Remember

• Urinary incontinence in children is common.
• Nighttime wetting occurs more commonly in boys.
• Daytime wetting is more common in girls.
• After age 5, night time incontinence disappears naturally at a rate of 15 percent of cases per year.
• Treatments of night time wetting include waiting, dietary modification, moisture alarms, medications, and bladder training.

Additional Resources
American Foundation for Urologic Disease
300 West Pratt Street
Suite 401
Baltimore, MD 21201
(Responds to written requests for patient information)

National Association For Continence
P.O. Box 8310
Spartanburg, SC 29305
(800) BLADDER or (864) 579-7900

National Kidney Foundation
30 East 33rd Street
New York, NY 10016
(800) 622-9010 or (212) 889-2210

The Simon Foundation for Continence
P.O. Box 835
Wilmette, IL 60091
(800) 23-SIMON

Society for Urologic Nurses and Associates
P.O. Box 56
East Holly Avenue
Pitman, NJ 08071
(609) 256-2335

Credits
National Kidney and Urologic Diseases Information Clearinghouse
3 Information Way
Bethesda, MD 20892-3580
NIH Publication No. 97-4095

What causes enuresis?
Though some studies suggest a slight predisposition in boys to have enuresis, there is no clear-cut difference between the sexes. Up to 25 percent of all wetters are described as having secondary enuresis. This means that the child has had a period of time (typically six to 12 months) being dry. In contrast, children who have never been dry are said to have primary enuresis. While some cases of secondary enuresis can be linked to a recent trauma or stress, their evaluation, treatment and response are generally no different than those with primary enuresis. In the past, when there were few treatment options, it was common to ignore or downplay the situation and hope for improvement with time. Today, with increasing opportunities for children to spend nights away from home (e.g., camps, sleepovers and overnight field trips), it has become a concern at an earlier age. It should be emphasized that the cause of all forms of enuresis is almost never due to laziness or deliberate willfulness by the child. So, a parent should keep a supportive and understanding attitude.

Urinary tract infection: The presence of a urinary tract infection can lead to wetting. The infection irritates the bladder, which can lead to urinary frequency and feelings of urgency. The bladder becomes irritated and can cause the child to wet suddenly. A urine culture is needed to diagnose an infection. When an infection has been found, it is common to conduct studies to look for an anatomical problem in the urinary tract that may have led to the infection.

Structural or anatomical problems: In most cases when enuresis is associated with an anatomic abnormality, there will either be a history of urinary tract infection or a history of persistent, continuous day and nighttime urinary incontinence . If either of these two findings is noted, X-ray tests will frequently be performed to rule out an underlying anatomical abnormality.

Neurological problems: Storing and emptying urine from the bladder is a complicated process. It involves the nervous system, which helps to coordinate the action of the bladder and its muscle groups. Children with a history of injury or disease of the brain, spinal cord or the nerves leading to the bladder can have enuresis. Examples include brain and spinal cord trauma or surgery, radiation therapy of the brain and spina bifida . These are among the most complicated cases and require a thorough urological evaluation.

What are some of the types of enuresis?

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Day and night enuresis: Day and night wetting can occur together. In those who wet day and night, both the day and nighttime wetting need to be addressed. Sometimes solving the daytime problem is emphasized first because the child can participate in the treatment more readily. During the day, the child is awake, alert and can assist in helping to keep dry. At night, the child is asleep and is unable to help directly. When there is day and night wetting it is often important to assess the toilet habits of the child. The daytime wetting may occur because of poor toilet habits, constipation or both. The toilet habits of normal children are different from those of adults. Many adults urinate three to four times each day and it is not unusual for them to pass eight hours between urinations. Children cannot be evaluated with these standards. Studies have shown that children normally urinate more frequently. Urinating up to 10 to 12 times by children between pre-school to early elementary school age is common. Few young children (under age eight years) urinate four or fewer times each day. Similarly, constipation in children often occurs with symptoms of fecal soiling rather than with the usual complaint of having "hard stools." Many children will also exhibit "avoidance maneuvers." These are repetitive actions that the child performs to suppress an urge to urinate. Leg crossing and squeezing, squirming and heel sitting are all common examples. When these maneuvers are observed it strongly suggests that the child is trying to suppress an urge to urinate. Sometimes these actions become habitual and the child may do them without realizing it.

Day-only enuresis: Children who wet only when have day-only enuresis. Because daytime control usually precedes nighttime control, this situation strongly suggests while the child is awake, some aspect of his or her life is making wetting more likely to occur. As noted above, the most common underlying cause is poor daytime toilet habits. A detailed history is often useful. Sometimes a diary of all urinations and bowel movements helps to see if there are any patterns to the accidents. An example is the boy who was wet only during the day, and when a thorough history and diary were obtained, it was found that the child was wet when he would play video games. To play longer, he did not use the "pause" feature of the game and learned to ignore the warning signals his full bladder was sending to his brain. Soon he was no longer noticing the early warning signs and was responding only to the late ones. Ultimately, he was often too late in responding and became wet. Correcting these habits improved the wetting.

Giggle incontinence: The complete or partial loss of bladder control that occurs with laughing or giggling while awake is referred to as giggle incontinence. It is a condition, which is well known enough to spawn the phrase "I laughed so hard that I wet my pants." It is most often seen in adolescent girls but can also occur in boys. There is no specific cause and the treatment is aimed at prevention with proper emptying of the bladder. It is usually a self-limiting condition that improves with age and maturity. Nocturnal enuresis (classic bedwetting): Experts believe this condition is caused by any combination of the following:

• Failure to arouse - the child does not wake up when the bladder is full.
• Increased production of watery urine during sleep - the child produces more urine during sleep than can be handled by the child's bladder.
• Size and volume mismatch - the child's bladder capacity has not caught up with the volume being produced.

Bedwetting is not believed to be due to a learning disability or psychological issue. It can, however, become a source of problems if the stresses and pressures from the enuresis severely affect the child or his/her family. Children who have nocturnal enuresis can develop fear of discovery by their friends and may suffer from teasing from siblings. They can become withdrawn and anxious. Family members, especially parents and guardians, are asked to be supportive and understanding. Remember that the child in nearly all of these cases cannot directly control what is happening. Although it may take longer than usual, children who are developmentally delayed can achieve control of their urination as long as their basic neurological function is normal.

Social stress such as a new sibling, sleeping alone, starting a new school, a family crisis, an accident or trauma can cause enuresis. Children who were previously able to control their urination may develop wetting after some dramatic event in their life, although the event may not necessarily be a "bad" event. In cases where the child had excellent control previously, continence usually returns although it may take weeks to months. Support, reassurance and patience by the parents are very important.

How is enuresis treated?

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There are several treatments for enuresis. They include modifications in fluid intake, toilet habits, the use of wetting alarm devices and medications. While they can be used alone, they are commonly used in combination. Stopping fluids before bedtime: All drinking of fluids is stopped one to two hours before bedtime. This is usually not effective by itself, but is a part of nearly every program. Fluids rich in sugar and caffeine promote urination in some children. Curtailing the intake of fluids rich in these substances is sometimes helpful. Remember that foods that may not seem to be fluids may actually be mostly water. Fruit, bowls of ice cream or cereal with milk and other "juicy" snacks are sometimes overlooked. They should be considered fluids and avoided before bedtime.

Scheduled night waking: The child is taken to the bathroom and is asked to urinate during the night by a parent or family member. This can also be done more than once during the night. Many families try this idea on their own before seeking medical attention. While it can be effective in the short term, it is hard to carry out in the long term. In some families where one or more adults work later shifts, they can take the child to the bathroom. It is labor intensive and does not consistently work. Sometimes the child will be wet soon after going to bed or after having been taken to the bathroom.

Bladder training exercises: Among men and women who suffer from various forms of incontinence , pelvic muscle exercises can be helpful. Usually the adults are asked to hold a full bladder and try to interrupt their stream consciously. An example is the woman who has had several children and who now spurts some urine whenever she strains when she carries a heavy load or when coughing. This situation usually does not apply to children. Children who hold their urine deliberately during the daytime may not help their situation. Rather than "stretching out the bladder," using these techniques in children promotes delaying of normal urination and may lead to subsequent urgency and daytime wetting.

Wetting alarms: Wetting alarms are small electronic devices that are composed of two components. One part is a sensor that attaches to the pajamas or underwear. The sensor is connected to the second part; an electronic alarm that is attached to the child's clothing near the shoulder or clipped to the waist. When the sensor becomes moist, the alarm is triggered. Some of the alarms also offer a vibration mode that makes a loud sound and vibrates. When the alarm triggers, the child attempts to get to the bathroom while the bladder is almost full. It usually requires an adult to help the child. The main advantage of an alarm is that it is not a medication and has no side effects. It also has a low relapse rate after the device is stopped. Its major disadvantages are that it cannot be used discretely on sleepovers and campouts. It may disturb siblings who share bedrooms. It does not always work in many children who may be heavy sleepers. Finally, most health insurance plans will not pay for alarm devices that can cost $60 to $120 each.

Medications: Several medications are commonly prescribed for the treatment of nocturnal enuresis. Some of these drugs have very serious side effects. They should never be used without the supervision of a physician. The medications may be used alone or often in combination with each other and with other treatments. The drugs include:

Desmopressin acetate (DDAVP): The human body naturally produces a hormone called vasopressin that causes the body to make less volume of urine. It is produced when the body is trying to conserve water. Athletes, for example, secrete more vasopressin into their bloodstream when they are playing because they are losing water from sweating. It was found that most people increase their secretion of vasopressin naturally when they sleep. That is part of the reason why most people sleep through the night without getting up to urinate. So, in the morning, the bladder contains urine that is more concentrated. In many children with nocturnal enuresis, this surge of vasopressin is absent. The hormone has been analyzed and synthesized as the drug, desmospressin, and is available as a pill or nasal spray. Because it works by decreasing the volume of urine produced, it must be used in conjunction with a fluid restriction program. Its primary advantage is that when it works, it can work very well, making it a confidence booster on sleepovers and campouts. It can be used discretely and is usually covered by most health insurance plans. The main disadvantages are that not every child will respond and the relapse rate can approach 50 percent.

Imipramine: This medication was for many years the only drug available for the treatment of nocturnal enuresis. Originally designed as an antidepressant, it was found to have an effect on nocturnal enuresis. It must be prescribed carefully and is usually given according to the child's age and weight. It must be stored carefully in a safety container. An overdose can lead to dangerous and potentially fatal irregular heart rhythms. Any suspected overdose of imipramine should be treated as an emergency.

Other medications: Oxybutynin and hyoscyamine are other medications which are sometimes used to treat nocturnal enuresis. They work by affecting the smooth muscle layers that line the wall of the bladder. These drugs act on the muscles to slow down their ability to contract; thereby causing the bladder to relax. Primary side effects include flushing with occasional heat sensitivity, dry mouth and constipation. These medications usually do not effectively work alone to treat nocturnal enuresis but may be helpful in children who also have daytime wetting.

Alternative therapies: Acupuncture, herbal remedies, chiropractic and hypnosis have all been tried as therapies. There are no scientific data that these methods have any consistent benefit in the treatment of enuresis.

Does bedwetting run in families?
It has been found that if one or both parents have a history of bedwetting, the risk that their child will be a bedwetter is several times greater than the general population.

Are there adults with bedwetting?
There are some adults with bedwetting. Some are helped by medication and may have to stay on medication indefinitely.

Does my child need further testing?
In most cases, there is no need to perform testing like X-rays and other imaging techniques. Conditions that may need more detailed evaluation include:

• combination of day and nighttime wetting
• urinary tract infection
• constipation and/ or bowel accidents
• difficulties with the urinary stream and flow
• history of recent neurological injury or disease

Your urologist will decide if tests are needed after speaking with you and examining your child.

Will the use of absorbent pants and other diaper-like products delay my child from ultimately gaining toilet control?
The use of absorbent pants has not been shown to prevent or delay the later development of toilet control. They do help decrease social friction between child and parents by making less laundry and decreasing the embarrassment caused by wet bed sheets.