Constipation in children

Contributed by Dr Nadeem Afzal, consultant in paediatric gastroenterology, hepatology and nutrition, Southampton University Hospital NHS Trust, and Dr Mike Thomson, consultant in paediatric gastroenterology, Sheffield Children's Hospital.

1. Epidemiology and aetiology
The prevalence of paediatric constipation in the UK is one of the highest in the world, at 34 per cent. It is a common paediatric problem that presents to GPs and hospital paediatricians alike.

Although constipation tends to occur equally often in both sexes below the age of five years, it is more common in boys after that age.

The most common form of constipation is idiopathic constipation; secondary constipation is rare.

Definition
Paediatric constipation is difficult to define. Normal bowel habits in children are subject to considerable variation and range from one bowel movement every other day to three every day. Breastfed babies may exhibit an increased frequency.

In July 2004, a group of paediatric gastroenterologists and paediatricians met in Paris to seek a consensus on childhood constipation terminology (see box).

Causes of secondary constipation

  • Coeliac disease.
  • Food allergy/intolerance.
  • Inflammatory bowel disease.
  • Metabolic/endocrine disorders.
  • Hirschsprung's disease.
  • Cystic fibrosis.
  • Cerebral palsy.
  • Lead poisoning.
DEFINITION

Paris Consensus on Childhood Constipation Terminology definition of chronic constipation.

The occurrence of two or more of the following characteristics, during the previous eight weeks:

  • Fewer than three bowel movements per week.
  • More than one episode of faecal incontinence per week.
  • Large stools in the rectum or palpable on abdominal examination.
  • Passing of stools so large that they obstruct the toilet.
    Retentive posturing and withholding behaviour.
  • Painful defecation.

2. Diagnosis
Constipation is diagnosed on the basis of clinical history and examination. The diagnosis may be obvious in some cases but not in others.

As a rule, all children presenting with abdominal pain should be carefully examined for constipation.

Constipation in children may also present with spurious diarrhoea with overflow, which can be misdiagnosed as true diarrhoea. Constipation should also be considered in any irritable child with a neurological diagnosis.

It is worrying when constipated children present looking pale or unwell with features of growth failure, 'overflow diarrhoea' with blood and mucus, when they do not respond to conventional treatments or the symptoms are severe. A number of investigations may be carried out in primary care (see box).

Referral
Children with any of these worrying features may also be referred to a secondary or tertiary care paediatric service.

Other referral criteria include: failed medical treatment; chronic prolonged symptoms; affected schooling and social relationships; restricted dietary intake; and soiling, regardless of frequency of bowel movements.

Hirschsprung's disease (absence of ganglion cells in the distal colon) is a common diagnostic worry. Suction rectal biopsy is the gold standard for diagnosing Hirschsprung's disease. However, in a study from our centre, we demonstrated that if the age at onset of constipation is after the neonatal period, Hirschsprung's disease is unlikely and a rectal biopsy is unnecessary.

INVESTIGATIONS

Primary care investigations

FBC
Ferritin
Coeliac screen and total IgA
Electrolytes including bone minerals
Inflammatory markers (ESR, CRP)
LFTs
Allergy testing


3.Treatment and prognosis
Recently published data from the US suggest that GPs tend to under-treat constipation. After two months of treatment, nearly 40 per cent of children remained symptomatic. Treatment success corresponded to how aggressively the child was treated.

Management
Management starts with explaining the physiological basis of constipation and soiling to the child and family. It is imperative that the child is not blamed for soiling. The family should be encouraged to adhere to the treatment plan. Any underlying psychosocial problems should be addressed; these range from bullying to the child being pressurised hurriedly to use the single family toilet.

At these crucial initial stages of management, it is sensible to see the child regularly. In practical terms this might mean two to three appointments, one to two weeks apart, either with doctors or a practice/GI clinical nurse.

Disimpaction
Disimpaction is essential for any maintenance treatment to stand a chance of working, particularly in severe cases. Using a strong stimulant at the start of treatment can precipitate an acutely painful episode in cases of impaction.

Diarrhoea in a constipated child starting treatment may only be spurious overflow diarrhoea. The correct treatment in this case is to increase rather than decrease the laxative dosage.

Once disimpaction has taken place, the aim of laxative treatment should be to keep the child symptom free with regular soft bowel actions. A useful rule of thumb is to aim for soft stools between once every other day to twice a day, although this frequency is not definitive by any means.

At this time the child should be encouraged to use the toilet regularly. The gastrocolic reflex is stimulated after eating, making after breakfast or mealtimes a good time for evacuation.

Conforming to a single uniform dosage of laxatives can be disappointing and treatment needs to be tailored to the individual child. Lactulose, macrogol and senna are treatments used in the UK. The first two are osmotic laxatives and the latter two are stimulants. Bulk-forming laxatives include ispaghula and methylcellulose. There are no randomised controlled trials comparing these treatments with placebo in children.

Once improvement is seen, laxatives should be gradually reduced rather than stopped suddenly. In chronic cases, the reduction should take place over months rather than days and can take two to three years or more in some cases. Relapse is common and may need to be treated with increasing laxative dosages.

Other treatments
A reward system with a star chart can be useful. However, toilet training should not be attempted in a constipated two-year-old until after they are disimpacted.

Diet plays an important role in childhood constipation. One study shows a useful effect of fibre on childhood constipation. It is common practice to recommend an increased fluid intake, but this can be detrimental to solid intake if over-done.

Prognosis
One study suggests an excellent prognosis for constipation in under-fives. Constipation resolved in 88 per cent of children in this age group, when followed over an 18-month period. The non-responders came from families with more psychosocial problems where treatment compliance was suspect.

Half of children with chronic constipation will be cured after a year of treatment and 65-70 per cent after two years. However, two studies have shown that around a third of children are still constipated three-12 years after beginning treatment.

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