Nocturnal Enuresis in Children

All children start life being incontinent of urine both by day and night and as neurological maturation occurs voluntary control of the bladder is gained first by day then by night. Very few never gain control of the bladder unless there is obvious neurological disease, including gross mental handicap. Hence, nocturnal enuresis in children should be seen not as a disease but as a variation of the normal rate of neurological maturation.

Three factors are commonly involved, a disorder of sleep arousal, a low nocturnal bladder capacity and nocturnal polyuria. Constipation may be an additional aggravating condition.¹

It is important to differentiate at the outset between primary nocturnal enuresis, when the child has never been reliably dry at night and secondary nocturnal enuresis when a previously reliable child starts to wet the bed again, not once or twice, but on a regular basis. This definition may include that the child should have been reliably dry for 6 months but the important factor is that it represents regression.

Primary enuresis most often represents developmental delay but it will be achieved with time whilst secondary enuresis represents a pathological process of regression. There may be a urinary tract infection (UTI) or a serious emotional upset.

Figures about the prevalence of nocturnal enuresis in children have to be taken with great caution as different studies use different criteria for definition. What is clear is that the prevalence of not being reliably dry at night falls as age rises and girls tend to be a little ahead of boys in terms of achieving control.

The Diagnostic and Statistical Manual of Mental Disorders (fourth edition) defines nocturnal enuresis as wetting at least twice a week. A large cohort study found that, using this criterion, the prevalence at 7 years old was 2.6%.² This represented 3.3% of boys and 2.3% of girls. A total of 15.5% were not totally reliably dry and occasionally still wet the bed.

Even by the teens, 1 or 2% occasionally wet the bed.

The approximate age-distributed prevalence of nocturnal enuresis is as follows:³

• 15% of 5-year-olds
• 7% of 8-year-olds
• 5% of 10-year-olds
• 2% of 15-year-olds
• 0.5% of adults aged 18-64 years

There are a number of factors that predispose to persistent nocturnal enuresis.

• There is a genetic predisposition.⁴ As an illustration, it is said that the risk of nocturnal enuresis is 15% if neither parent was affected, 40% if one parent was affected and 75% if both had the condition.⁵
• Developmental delay is to be expected in those with global developmental delay, with or without an associated syndrome such as Down's syndrome.
• Even without gross developmental delay, there is more likely to be persistent bed wetting in children with delayed developmental milestones, premature delivery or behavioural disorders such as hyperactivity or inattention deficits.⁶
• There may be neurological problems such as spina bifida or cerebral palsy. Those with physical problems are more likely to have daytime enuresis or trouble with encopresis. Physical problems are a rare cause of nocturnal enuresis per se.
• Constipation can cause bladder problems.⁷ In an American series, those with severe constipation even causing encopresis, benefited from treatment of constipation and cured about two thirds of nocturnal enuresis.⁸ There was also a high rate of urinary tract infection, affecting 3% of boys and 33% of girls.
• Risk factors include disturbed sleep,⁹ mother aged less than 20 at time of birth, mother smokes at least 10 cigarettes a day at home and not being first born.¹⁰ In that survey, only 50% of parents had consulted a doctor about enuresis. Afro-Caribbean children seem to have a slightly higher incidence than white children and only 35% of the families had consulted a doctor. These risk factors have not changed in 45 years.
• Airways obstruction with snoring increases risk.
• Drinks containing methylxanthines can aggravate the situation by their diuretic action. These include tea, coffee, cola and chocolate.
• There is no evidence that early potty training prevents bedwetting.
• Stresses in the child's life such as an admission to hospital with separation from the mother or bullying are more likely to cause secondary enuresis. The older the child, the more likely it is that psychological problems are the result of enuresis and not the cause.

Recent studies suggest that patients who respond best to desmopressin (see Management, below) have a larger than average nocturnal urine excretion rate and a pronounced arginine vasopressin deficiency.¹¹

When a parent presents with a child with the complaint of persistent nocturnal enuresis, it is interesting to find what has prompted the consultation. There may have been talk amongst parents and the mother is embarrassed to find that her child is less advanced than his peers. There may be problems of "sleep overs" in a friend's house or going to camp with a youth group. Generally, those who run such camps are very familiar and competent about the problem, especially as disturbed sleep and great excitement is to be expected. However, it can be a great source of embarrassment and teasing. Children can be very cruel. Holidays can also be difficult if a relatively large child still wets the bed.

• Note the age of the child. If less than 5 years, simple reassurance is in order. Most management protocols are aimed at children who have passed their 7th birthday. The older the child, the more seriously the complaint should be taken.
• Elicit the nature of the problem. Is the child wet every night or most nights? Is he wet perhaps just once a week or often more than once a night? This indicates the severity of the problem. If it is near to solution, perhaps minor adjustments are necessary or just patience is required as maturation occurs.
• Has the child ever been reliably dry? Primary and secondary enuresis are two separate matters.
• At what age were sibs reliably dry? Were the parents late in achieving nocturnal control? If it appears that all the family are late but everyone gets control in the end, this is reassuring.
• Check that there is good control of urine by day.
• Ask about bowel habits. Constipation is a common cause of urinary problems.
• Is there polyuria or polydypsia?
• If other urinary symptoms are present, consider other conditions such as overactive bladder.¹²
• What have the parents been doing in terms of management? They may be restricting fluids or lifting the child from bed to the toilet before they retire at night.

Unless the child is less than 5 years old or has only occasional enuresis, a mid-stream urine should be sent for culture. Urinary tract infection in children is an uncommon cause of either primary or secondary enuresis, but when it does occur it is important that diagnosis is made with referral for appropriate investigations. Many protocols for treatment will demand a negative MSU before commencement.

If the child drinks a great deal, check the urine. This is a very uncommon presentation of diabetes mellitus at this age but check for glucose. Also check the specific gravity of an early morning specimen. Diabetes insipidus may be incomplete and failure of enhanced ADH production overnight can be a problem. Check for albumin too. Chronic renal failure can present with failure of concentration. If the child is growing normally and doing well at school, it is unlikely that there are any serious physical problems.

Arginine vasopressin deficiency can be assessed by measuring the nocturnal urine volume, although this may not be easy to arrange in primary care.¹¹

It is essential that the parents understand that this is just a matter of relative delay in psychomotor maturity and that the child will achieve control at some stage. Some facts and figures about numbers still bedwetting at various ages may help to reinforce this. It is also important to understand that the child does not wet the bed out of malevolence or defiance. It is important to try not to be angry with the child, although this may be difficult at times. Stress aggravates the problem. Instead, reinforce success.

Secondary enuresis

Secondary enuresis is when the child has previously been reliably dry at night, perhaps for 6 months or more. It is highly significant because it represents regression.

• Urine for culture is extremely important as the chance of UTI in this group is much higher than with primary enuresis.
• Loss or impairment of bladder control by day is possible with UTI but other problems such as clumsiness or falls may suggest a neurological problem. This demands neurological examination and referral.
• An extremely important cause of regression is emotional upset. This tends to occur at times when continence has not been established for very long and so it is less often the problem in older children or adolescents. It is said that the psychopathology is a desire to regress to the times when the child was younger and did not have to cope with such problems. Problems may include troubles in the family such as parental separation or illness, bullying at school or sexual abuse.
• It may not be easy to elicit the cause of the problem and if the doctor is convinced that there is such a problem that needs to be uncovered and addressed, referral to a professional such as a child psychologist may be required.

Primary enuresis

Basic Principles

• If the child is less than 5 years old, then reassurance and waiting is in order. This may also be true with a slightly older child if there is a family history of late acquisition of control or if wetting is only occasionally and it appears that reliable control is imminent.
• The child should empty his bladder before he goes to bed. This is common sense and what adults do.
• Fluid restriction is not recommended, especially as the problem may be inadequate response to ADH. On the other hand, drinking freely before bedtime is not sensible and in the evening avoid drinks containing methylxanthines.
• Waterproof undersheets are a sensible precaution to avoid ruining mattresses.

Raising in the Night

Many parents choose to take the child to the toilet before they go to bed, so that the child may empty his bladder and, in effect, have a shorter night in which to need control. There are two ways of doing this.

• The child may be roused and fully awake. He walks to the toilet, passes urine and walks back to bed. By now he is fully awake and probably wanting to be up and play for a while rather than going straight back to sleep whilst the parents are eager to get to bed. That is the problem with this technique.
• The other technique is gently to lift the sleeping child. Take him out and sit him on the toilet and encourage him to pass urine. Then gently pick him up, carry him back to bed and tuck him in. This technique is very commonly used and is recommended by such authorities as the Royal College of Psychiatrists.¹³ It is however only usually useful as a short-term and temporary measure.³

Behavioural modification

This takes 3 main forms.

Star Charts

The aim is to reinforce success rather than to punish failure. Remember that the child does not choose to wet the bed at night. The star chart requires a calendar and some sticky stars. Every time that the child has a dry night, a star is placed on that date. If it is not a dry night, that date is ignored. The star is a reward. There is no punishment. Perhaps a run of success, such as 7 consecutive stars, may merit a treat.

For this to be viable, the child must have a significant number of dry nights already. The natural history of the condition is that it will improve and it is difficult to be sure that the technique is really accelerating achievement of control, rather than just acting as psychotherapy for the parent. The value of simple interventions is not clearly demonstrated.¹⁴

Enuresis Alarms

The buzzer and pad has been in use for around 50 years and efficacy has been demonstrated.¹⁵ The aim is to wake the child as he starts to urinate, so that he will stop, go to the toilet and learn to recognise the nocturnal sensation of a full bladder.

The structure of the system is that above the waterproof sheet over the mattress is a mesh pad. A normal sheet is on top of this and another mesh pad on top of that. Both pads are at around the level where the child's pelvis and thighs will be. There is a further sheet on top of the upper pad. The pads are on each end of a circuit that includes a battery and a buzzer. When the child starts to urinate, the urine, that contains electrolytes and is a good conductor, will sink down and complete the electric circuit between the pads and the buzzer will sound. At this, the child wakes and goes to the toilet to finish passing urine. Older children are expected to strip the wet sheets, remake the bed and reset the buzzer.

Most providers of buzzers and pads insist that the child should be at least 7 years old and have been checked for UTI. The loan of the device is usually limited to 3 or 6 months.

A common cause of nocturnal enuresis is that the child sleeps so deeply that he does not respond to the sensation of a full bladder. There are many stories of children who sleep so deeply that the buzzer has awakened the whole family with the exception of the one it is supposed to wake.

Complex behavioural and educational interventions

A Cochrane review found that there was little evidence to support the use of complex interventions (e.g. dry bed training in which the child is encouraged to go to the toilet frequently and change their own sheets) per se, although such training in combination with a buzzer may be better than the use of a buzzer alone.¹⁶

Alternative Medicine

A Cochrane review found poor evidence to support hypnosis, psychotherapy, acupuncture and chiropractic.¹⁷ Each case was supported by single small trials, some of dubious methodological rigour. There is no logic to the use of any of these.

Drugs

There are a number of drugs that have been used over the years. They do not "cure" the problem but may help in achieving the aim. The BNF states that the enuresis alarm should be used before drugs but they can be used in combination. Drugs may also be used short term to cover a specific time such as holiday or going to camp.

• It has been mentioned earlier than deep sleep is a common problem. Drugs such as ephedrine and pseudoephedrine can make sleep lighter so that the child is more likely to awake with the sensation of a full bladder. However, this is not a licensed indication. It may cause sleep disturbance and behavioural problems. Pseudoephedrine is known to cause nightmares in small children.
• Tricyclic antidepressants, usually in the form of amitriptyline or imipramine, may be used for their anticholinergic side-effects. They can cause behaviour disturbance. Relapse often occurs on stopping them¹⁸ and they should not be used for longer than 3 months without reassessment.
• Desmopressin is a synthetic analogue of ADH and has become the most popular form of drug treatment for this condition. As there is evidence that in some cases the problem is inadequate response to ADH overnight, it has physiological rationale. The oral route should be used for this indication (not nasal).¹⁹ It is important to avoid fluid overload after taking it. It should be reassessed after 3 months by taking a break. It does seem to be effective but possibly less so than an alarm.²⁰
• A Cochrane review found 28 other drugs that had been used, including NSAIDs, but none had good supporting evidence or were as effective as desmopressin.²¹

Measuring success

As mentioned earlier, there are many different statistics for the prevalence of nocturnal enuresis at various ages, depending upon the criteria used for definition. The definition of success is similarly varied. A successful outcome should be taken as one in which the child is reliably dry rather than invariably dry. To some people, success is not simply achieving a dry night, but responding to the stimulus of a full bladder and getting up to empty it without wetting the bed. Most people sleep all through the night but if the stimulus arises, it is important to respond appropriately.

• Bedwetting can be very distressing, especially for older children and it may lead to social isolation, bullying and low self-esteem. Whilst an expectant approach is appropriate for younger children, older children need a more active approach.
• If enuresis persists into adult life, there may be severe psychosocial problems affecting self-esteem, careers, social life and personal relationships. It is unpleasant to sleep with a bedwetter.
• Parents have extra work and cost of extra laundry along with the additional stress of caring for a child with enuresis. Up to 30% of parents become intolerant of the enuresis and consequently also of their child.

Everyone who does not have a serious neurological defect or severe learning difficulties can expect to achieve nocturnal continence sooner or later. Even after dry nights have been reliably achieved, the occasional "accident" is still to be expected and is no cause for concern unless there is apparent regression. Those with a family history of late nocturnal continence, those with behavioural disorders and those with developmental delay will take longer. Boys tend to take longer than girls but all cases are highly variable.

One study found that children with the severest form of bedwetting are likely to persist with the problem and to have the more complex form (non-monosymptomatic) which persists into adolescence.²² A typical scenario is after a night of heavy consumption of beer. The alcohol causes deep sleep and the volume puts the bladder under great stress. Those at risk need to be more restrained in their drinking habits.