Enuresis (bedwetting)

Definition

Enuresis (bedwetting) is generally defined as the persistence of inappropriate urination beyond the age when control would be expected.

It is worth noting that the term "bedwetting" is often used interchangeably with "enuresis". Strictly speaking, enuresis refers to involuntary urination during the day or night. People often use the term enuresis when they are in fact referring to nocturnal enuresis.

Classification

Enuresis (bedwetting) is not a single entity and can be classified as follows:

• Primary: inappropriate voiding since birth
• Secondary: inappropriate voiding which develops after the child has been dry for at least six months
• Nocturnal: inappropriate voiding occurring at night
• Diurnal: inappropriate voiding both day and night
• Polysymptomatic: inappropriate voiding which occurs with any of the following symptoms: urgency, urge incontinence, or staccato voiding of urine
• Monosymptomatic: nocturnal enuresis without any other symptoms

Causes

There are many possible causes of bedwetting:

• Genetic factors
• Sleep problems
• Reduced functional capacity of the bladder, meaning that the bladder cannot hold as much urine as in a normal child, without the need to urinate.
• Nocturnal polyuria – the production of large quantities of urine at night
• Bacterial infection of the urine
• Allergic reactions
• Psychological factors
• Developmental delay
• Neurogenic bladders

There is much interplay between these factors, which explains why every child responds differently to treatment.

Most bedwetting probably results from delayed development of the nervous system with regard to the recognition and response to bladder fullness and contraction during sleep. This will result in a delay in the ability to suppress the urge to urinate at night.

Children who suffer from secondary enuresis are more likely to have a psychological or physical (organic) cause for their problem.

Who suffers from enuresis and who is at risk?

Complete daytime and nocturnal control of urine is achieved by 55% of three-year-olds, and 77-85% of five-year-olds.

Nocturnal enuresis is present in 15-20% of five-year-olds and 7% of seven-year-old children. After the age of seven, the incidence decreases by 1% per year of age.

The male to female ratio is 1,4 : 1.

Children who have problems with bedwetting gain continence at a rate of 15% per year after the age of five. This means that 1-5% of children at puberty and 1.5-3% of adults have episodes of nocturnal enuresis.

A five-year-old child with enuresis has a 70% chance of continuing bedwetting at the age of eight and a 40% chance of wetting at the age of ten.

Secondary nocturnal enuresis occurs in 3-8% of children aged five to 13 years. Children in this group are more likely to have a psychological reason for bedwetting.

There is a 44% chance of enuresis in children who have one parent who wet the bed. This rises to 77% if both parents suffered from bedwetting.

Examination

Every child older than five who wets the bed should have a full medical examination and an analysis of their urine.

Children who have never been dry (primary enuresis), who have no daytime symptoms and have a normal urine analysis, do not need any further investigations. Any child who does not fall into this category needs investigation.

Daytime symptoms are particularly important in suggesting some underlying medical cause of involuntary urination.

The history (what the parent and child tell the doctor) should establish whether there are any daytime symptoms.

Children with diurnal enuresis abnormalities on physical examination or urine tests need to be examined further.  This includes ultrasound of the bladder and kidneys, x-ray examination of the bladder (cystogram) and/or a functional bladder test (urodynamic study).

Treatment

Parents of children who wet need to have a full explanation of the incidence and the causes of bedwetting explained. Spontaneous resolution is common, the child does not wet the bed deliberately and this is not a sign of deep-seated psychological problems.

It is important to have a motivated child, not only motivated parents before treatment commences.

There are certain common tasks for affected children and their parents. The child is asked to keep a "voiding diary", showing night-time and day-time episodes of voluntary and involuntary urination, any associated urgency, the number of wet nights, the number of episodes per night and the size of the wet spot. The diary should be started at least two weeks before the onset of treatment.

A motivational star system is recommended. Stars are awarded for dry nights, with a reward for a certain number of dry nights.

A successful treatment has been with a so-called enuresis alarm, offering the best long-term results. For this to be successful both child and parents need to be motivated and the child old enough. The enuresis alarm consists of a bell-and-pad or sensor worn inside or on the child’s underclothes. When the pad/sensor becomes wet, the alarm sounds, waking the child and resulting in bladder contraction ceasing. The child then needs to wake up fully and get out of bed to pass urine. This is most effective when used along with a star chart and diary. It is not a “quick fix”, and will take time and patience from all concerned.

Drug treatment

The antidepressant imipramine is widely used in South Africa. It affects both bladder tone, increasing functional bladder capacity, and decreases the depth of sleep. Initial success with imipramine occurs in 20-43% of children, with the resolution of the problem in around 35% by six months. However, there is a relapse rate of 70-84% reported and at one year only 16-30% of children remain continent.

Treatment is started at a dose of one milligram per kilogram per day, given at bedtime, and increased to a maximum of 2.5 milligrams per kilogram. It is usually prescribed for three to six months and the drug is gradually decreased in dose before it is stopped. Side effects occur in about 10% of children and include anxiety, behaviour and personality changes, gastro-intestinal disturbance and hair loss.

Desmopressin is a synthetic form of a hormone called antidiuretic hormone, which controls the way in which water is transferred across membranes. Desmopressin decreases nocturnal urine output, thus delaying the time it takes for the bladder to fill to a level where it needs to void.

Successful treatment with desmopressin occurs in an average of 68% of children. Those with a family history of enuresis seem to respond somewhat better than those without.

Desmopressin is more successful in children older than nine and in those with fewer wet nights. It is far more effective in monosymptomatic than in mixed enuresis.

Relapse rates of between 60-90% after stopping desmopressin occur, but this decreases if the drug is withdrawn gradually.

It is useful for short-term therapy such as sleep-overs with friends and is sometimes used in conjunction with other treatment.

However, it is very expensive, particularly compared with imipramine.

It was previously only available as a nasal spray, but is now available in tablet form in South Africa.  Side-effects are electrolyte disturbances, and blood tests should be done after 2 weeks of treatment.

Outcome

Most cases of primary enuresis resolve spontaneously. After the age of seven, the incidence of bedwetting decreases by about 1% per year.

When to see your doctor

Any child who wets the bed should be seen for a full medical examination and urine analysis.

If your child has been dry and then starts wetting the bed, you should see a doctor.

Dr Frans van Wijk, FCS (Urol), Pretoria Urology Hospital, January 2011