Childhood constipation

Dr Samar Razaq discusses the management of a child with worsening constipation.

Case study

A five-year-old boy attends with his mother. He has been seen several times in the past year with constipation and faecal soiling. His medication list includes a range of laxative prescriptions.

He was fully toilet trained at the age of three and started to suffer mild bouts of constipation when he joined nursery about a year ago.

Since then, the problem has gradually worsened. His mother explains how he occasionally stands in the corner, legs crossed, buttocks clenched and in obvious distress. He is oblivious to the fact that his underwear is usually marked with loose stool as he has no recollection of passing it.

His mother explains that she would start him on the laxatives, but stop within days because diarrhoea would develop. This is causing great distress in the family and affecting the child's self-esteem.

The boy had a complication-free birth and is otherwise growing well. Examination reveals a slightly distended abdomen with palpable stool in the left lower quadrant. His mother is confused about why every doctor she sees keeps prescribing laxatives when the boy seems to be constantly leaking loose stool. What would you do next?

Chronic constipation is a common paediatric problem. The estimated prevalence is 5-30% in childhood and it may be a source of physical, social and psychological distress.

The first step in the management of constipation is differentiating between functional and organic causes. Management of the latter is determined by the underlying cause.

In most cases, functional constipation can be managed in primary care. Effective management requires that the GP and carers understand the underlying processes leading to functional constipation, so motivation for treatment is sustained in what can be a tortuous recovery.

Underlying cause

Although the underlying cause is unclear, it may develop after an initial bout of constipation, during which the passage of stool becomes associated with pain. This may occur after a mild illness, dehydration or stressful toilet training.

The child tries to avoid the pain by preventing the passage of stool. The stool hardens further, making it more painful and causing the possible development of anal fissures.

The cycle continues and the stool hardens further and the pain increases. In severe cases, the child actively holds their stool (manifested by leg crossing and buttock clenching), which parents often mistake for an unsuccessful attempt to pass stool.

As the faecal load in the rectum increases (leading to reduced sensitivity in the rectum), looser stool from above (due to the laxatives, which have usually been started by now) bypasses the faecal mass and exits the back passage, with the child often unaware of this happening.

This is usually mistaken for diarrhoea and wrongly results in the laxatives being stopped.

Diagrams to show faecal impaction, rectal enlargement and insensitivity, and overflow incontinence may be used to help parents understand what is happening and comprehend the rationale of the various treatment modalities.

Investigations are rarely necessary for functional constipation. Abdominal X-rays are not recommended in its routine management.

Blood tests may be performed to rule out some of the organic conditions listed in box 1, although the Guthrie test should have picked up most cases of hypothyroidism and cystic fibrosis. A thorough examination is indispensable.

Management

Important lifestyle changes should be thoroughly explained before treatment is commenced.

The child should be encouraged to sit on the toilet daily. Fluid and fibre intake should be increased, coupled with restrictions in dairy, as these measures have been shown to reduce constipation. Removing dairy from a child's diet, particularly for a long period, is usually not feasible, but a short trial should be encouraged.

Sorbitol-containing fruit juices (apple, pear) may be recommended in infants to help soften the stool.

The purpose of laxative therapy is to maintain a regular bowel habit. Parents should be made aware that treatment is likely to continue for some time beyond the achievement of a regular bowel movement, owing to the high risk of recurrence.

If impaction is suspected (as in this case), it is desirable to perform disimpaction first, as a large faecal mass is unlikely to pass on demand. While there is no agreed 'best method' for this, all therapeutic options may be considered. In children, high-dose oral macrogols may be used to achieve this aim.

A reasonable regimen in this child would be to start with four sachets daily, gradually increasing to 12 sachets daily if needed.

Other osmotic or stimulant laxatives may be used to promote the passage of stool. In children over three years old, an arachis oil enema can be used in resistant cases.

Sodium citrate or phosphate enemas may be used if these methods fail. Occasionally, bowel cleansing preparations or manual evacuation under anaesthetic are needed.

Once disimpaction has been achieved and maintenance therapy started with one or more laxatives, regular review is necessary, to ensure regular bowel movements have been established and to discuss any concerns the parents may have.

  • Dr Razaq is a GP in Slough, Berkshire

Resources

  • NICE. Constipation in children and young people: diagnosis and management of idiopathic childhood constipation in primary and secondary care. London, NICE, November 2011.
  • Biggs WS, Dery WH. Am Fam Physician 2006; 73: 469-77, 479-82.

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