Primary Nocturnal Enuresis is used to describe the condition where a child has never attained bladder control during the night. Secondary Nocturnal Enuresis is used to describe the condition where a child starts to wet the bed after at least six months of nocturnal bladder control.
A child is generally not classed as a bed wetter unless he or she wets the bed more than twice a week after the age of 5.
Research indicates that nocturnal enuresis is one of the most common paediatric health issues. It affects approximately 15-20% of 5-year-olds, 5% of 10-year-olds, and 2% of 15-year-olds.1,2 Approximately 1% of adults continue to suffer from nocturnal enuresis.
Under 13 years of age about twice as many boys as girls have nocturnal enuresis. Above 13 years of age it is more frequent in girls.3
Nocturnal enuresis will spontaneously cure in around 15% of children who suffer from it each year, independent of age.
The epidemiology of bedwetting tends to indicate that nocturnal enuresis is a variation in the development of normal bladder control rather than a disease state.4 Causative factors can include an undeveloped bladder reflex, inhibited nocturnal production of anti-diuretic hormone (ADH) which reduces the amount of urine produced by the body during the night time, and small functional (as opposed to actual) bladder capacity.
The bladder relies on muscles to contract and release when the body is ready to urinate. The internal sphincter is the primary muscle for prohibiting the release of urine from the bladder. It is a smooth muscle and is under involuntary or reflex control. The external sphincter is the secondary muscle controlling the flow of urine through the urethra. It is a skeletal muscle and therefore it can be consciously controlled.
In children suffering from nocturnal enuresis the signal to the brain to wake when the bladder is full is weak or inoperative and the internal sphincter allows automatic, involuntary voiding when the bladder fills above a certain level. Also, some bed wetters do not produce enough ADH to allow them to sleep right through without going to the toilet. If the bed wetter does not wake in response to the feeling of a full bladder or the subsequent involuntary voiding they are unable to consciously clamp the external sphincter muscle to stop the urine flow.
Furthermore, research indicates that children with nocturnal enuresis often have a small bladder capacity compared to their peers.8 They tend to go to the toilet more often during the day and sometimes suffer from urge incontinence. Interestingly, however, when children with small bladder capacity are examined under anaesthesia, their bladders are normal in size. This implies that the child suffers from a sensation that the bladder is full before it actually is. The medical term for this condition is small functional bladder capacity.
There is a genetic pre-disposition towards nocturnal enuresis. If one parent was a bed wetter then the child has a 44% chance of being a bed wetter. If both parents were bed wetters then the child has a 77% chance of being a bed wetter.5
In a minority of cases bedwetting is caused by anatomic, urological or neurological defects. In some cases secondary nocturnal enuresis may appear following emotional distress e.g. the birth of a new child, moving house, or death of a relative. Children with secondary nocturnal enuresis should be checked for organic, neurological or psychosocial factors.6
There is anecdotal evidence that many parents and general physicians are unaware of the range of treatments for nocturnal enuresis. Indeed, in New Zealand, less than half of parents with a bedwetting child consult a doctor about the problem.3 Anecdotal evidence from other countries also suggests that when a child is seen by a physician for bedwetting the most prescribed course of action is to let it run its own course. The majority of parents find this solution unhelpful.
Research has indicated that bed-wetting in children aged 5 years and older, irrespective of its frequency, is associated with increased rates of behavior problems. So, although infrequent bed-wetting may not warrant medical intervention, this condition should prompt health care providers to explore behavioral issues in greater depth.7
Due to the emotional stigma that often accompanies this condition, bedwetting can lead to self-esteem issues in children and disrupt family routines, increasing the amount of housework required to keep a child dry and clean. For these reasons a safe treatment regime with minimal side effects is highly recommended if a child is ready and wants to cure their bedwetting.
There are a three main treatments for bedwetting, either used separately or in conjunction with each other: - Bedwetting Alarms - Behavioural Therapy - Pharmacological Therapy
Bedwetting alarms work on the principle of Conditioned Learning. This principle was discovered by Pavlov, a Russian psychologist in the early 1900s. He found that if a powerful stimulus is associated with a neutral one then after a time the neutral one acquires the same strength as the powerful one. In his work with dogs Pavlov found that putting food in a dog’s mouth was a powerful stimulus triggering the production of saliva. He then experimented with ringing a bell each time he gave the dog some food and after a time he found that simply ringing a bell would result in the dog producing saliva. People are also affected by this kind of learning and mostly we are completely unaware that it is happening. Whenever a powerful and neutral stimulus occur together a link is made. In the case of bed wetters the sensation of a full bladder should trigger awakening but it doesn’t.
However, the sound of a loud noise can trigger waking and cause an immediate contraction of the external sphincter muscle which stops the flow of urine from the bladder. The solution is to pair up the feeling of a full bladder with a loud noise so that, in time, the sensation of a full bladder will do the waking just like a loud noise. Bedwetting alarms work by placing a sensor in the child’s underwear that sounds an alarm when a small amount of urine is released, waking the child up. Over time the child gradually learns to associate the sensation of a full bladder with the need to awaken and eventually the bladder reflex will function correctly and let your child sleep through the night.
Enuresis alarms are the treatment of choice in motivated children over 7 years of age. The initial success rate of alarms on their own is 65-80%. A child given an alarm programme is 13.3 times more likely to achieve 14 consecutive dry nights.2
Simple behavioural therapy reinforces that while it is not the child’s fault the treatment is the child’s responsibility. Reward systems involve positive reinforcement like sticking stars on a calendar for dry nights but no negative reinforcement for wet ones. However, it may be difficult to convince a child that a wet night is nothing to be ashamed of when dry nights are rewarded. Rewards may increase a child’s vigilance for a while making his or her sleep lighter and by this means controlling the bladder and not wetting the bed. However, because behavioural therapies used on their own do not train either the child’s brain to wake with the sensation of a full bladder or the bladder reflex system to stop urine leakage, complete cure is unlikely in the majority of cases. When motivational therapy is used alone, the cure rate is approximately 25%.9 ‘Lifting’ or waking a child in the middle of sleep to toilet can lead to frustration and conflict, especially if the child does not feel he or she wants to go to the toilet. Any attempt to force a child to go to the toilet before bed or during sleep will not bring any improvement in bladder control unless, fortuitously, it coincides with the sensation of a full bladder and the child is aware of this.
Synthetic hormones such as Desmopressin (Minirin), or antidepressants such as Imipramine, may be prescribed for bedwetting. Treatment with synthetic hormones reduces the amount of urine produced during the night whereas antidepressants make the bladder muscle relax whilst causing the smooth muscle at the bladder neck to contract, inhibiting involuntary urination. Drug treatment is relatively expensive and runs the risk of uncommon but severe side effects. In the case of Desmopressin it needs to be used with great caution in children who have problems with fluid balance or cystic fibrosis because excessive fluid intake can affect the fluid balance in the brain leading to confusion or even convulsions. Also, it tends to be ineffective with children with viral or symptomatic allergic rhinitis. Imipramine can lead to emotional irritability in children and there is the possibility of accidental overdose which can lead to convulsions and coma.
Desmopressin can be effective for short-term treatment when on camp or sleepovers and Imipramine can be effective for short term treatment of distressed, older children if other treatments have been unsuccessful. Drugs do not cure bedwetting long term. Once a child stops taking them the reported relapse rates are 59-100%.9
Research indicates that bedwetting alarms have the highest success rate in treating nocturnal enuresis compared to other treatments. Another advantage of bedwetting alarms is that they are cost effective, do not require medication and have no side effects.
Treatment with an alarm can take just a matter of weeks in some cases to several months, or more, in others. Any successful treatment programme, requires a motivated child and supportive parents.