A BED WETTER
History
Alvin is a 9-year-old black British boy who has been referred to paediatric outpatients because of bedwetting. He is accompanied by his father. He wets the bed most nights, does not wake up when it happens and there is a large pool of urine. He has no previous medical problems and no recent illnesses. His father says he is unsure if there is any family history of bedwetting. They tried using an enuresis alarm 2 years ago, and the alarm woke him up but he was already wet so they gave up after 1 week. Alvin is quite upset about his bedwetting, particularly because he recently wet the bed when he stayed at a friend’s house and has been teased about this at school. Alvin’s father is despairing and has started waking him at night to go to toilet, but sometimes he is already wet. He says this is affecting his ability to work and he feels that Alvin is being lazy and should be able to control his bladder at this age.
Examination
His height is 140 cm (75th centile) and his weight is 35 kg (75th centile). His blood pressure is 112/70 mmHg. Cardiovascular, respiratory and abdominal examinations are unremarkable.
INVESTIGATIONS
Normal
Urine analysis
Leucocytes Negative Negative
Nitrites Negative Negative
Blood Negative Negative
Glucose Negative Negative
Specific gravity 1.002 1.002–1.035
Questions
• What further history is required?
• What further examination is necessary?
• What are the options for management?
Medicine
Nocturnal enuresis is defined as involuntary voiding of urine during sleep at least three times per week in a child aged 5 years or older. Approximately 10 per cent of 5-yearolds and 5 per cent of 10-year-olds are affected. It is essential to establish if this is primary or secondary. Primary nocturnal enuresis indicates that he has never achieved dryness at night and three mechanisms may contribute to this: lack of arousal from sleep, bladder instability or low functional bladder capacity, and nocturnal polyuria due to low vasopressin levels. Secondary enuresis indicates that he had previously achieved dryness at night for at least 6 months and something has happened to cause bedwetting again. Secondary causes include constipation, urinary tract infection, diabetes mellitus or psychosocial stresses, such as bullying or a recent parental separation. It is important to establish if there are daytime symptoms of urgency, frequency, dysuria or wetting, which suggest bladder instability or urinary tract infections. An accurate diary of fluid intake and voiding throughout the day is helpful. A family history of bedwetting, renal problems and sickle cell trait/disease (associated with reduced urinary concentrating ability) should be sought. Examination should include plotting the child’s height and weight on a growth chart and a urine analysis. In addition, the genitalia and spine should be inspected for abnormalities, and lower limb neurology should be assessed.
Management options for primary nocturnal enuresis
• Self help measures – regular daytime fluid intake and voiding, avoid caffeinated drinks
• Enuresis clinic support
• Nocturnal polyuria – desmopressin (synthetic analogue of antidiuretic hormone)
• Lack of arousal – enuresis alarm with star chart
• Bladder instability – bladder retraining, anticholinergic medication
In this case, there are features of both nocturnal polyuria and lack of arousal from sleep. Unfortunately the father is not sympathetic and unlikely to have the commitment to make an enuresis alarm succeed. In this setting, desmopressin may provide some respite to the family. This will reduce nocturnal urine production. It is important to emphasize early that this is not something Alvin has any control over, that desmopressin is not a solution in the very long term, and that ultimately he may need other methods of treatment. Desmopressin can be withdrawn in a structured fashion, assisted by the use of an enuresis alarm, when the family are ready to support Alvin and invest some effort in his treatment. It may take a long time to achieve consistent dryness through the night. The family may need psychological support. Desmopressin can cause headache, nausea and abdominal pain, and may be dangerous if there is excessive fluid intake.
KEY POINTS
• Nocturnal enuresis is very common and should only be investigated in children older than 5 years.
• It is essential to establish if nocturnal enuresis is primary or secondary.
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