Paediatrics: Constipation

Constipation

Defined as infrequent passage of stool associated with pain and difficulty, or delay in defaecation.

•   95% of infants pass   1 stool/day.

•   95% of school children pass   3 stools/wk.

•   Constipation is common in childhood.

•   Approximately 5% of school children suffer significant constipation, usually functional.

•   Organic cause more likely if: delayed passage of meconium beyond 24hr of age; onset in infancy; severe; associated with faltering growth or abnormal physical signs (include per anal examination).

Causes

Idiopathic

Commonest due to a combination of:

•   Low fibre diet.

•   Lack of mobility and exercise.

•   Poor colonic motility (55% have a positive family history).

Gastrointestinal

•   Hirschsprung’s disease.

•   Anal disease (infection, stenosis, ectopic, fissure, hypertonic sphincter).

•   Partial intestinal obstruction.

•   Food hypersensitivity.

·  Coeliac disease.

Non-gastrointestinal

•   Hypothyroidism.

•   Hypercalcaemia.

•   Neurological disease, e.g. spinal disease.

•   Chronic dehydration, e.g. diabetes insipidus.

•   Drugs, e.g. opiates and anticholinergics.

•   Sexual abuse.

Presentation

•   Straining and/or infrequent stools.

•   Anal pain on defaecation.

•   Fresh rectal bleeding (anal fissure).

•   Abdominal pain.

•   Anorexia.

•   Involuntary soiling or spurious diarrhoea (liquid faeces passes around solid impaction).

•   Flatulence.

•   ‘fall’ Growth.

•   Abdominal distension.

•   Palpable abdominal or rectal faecal masses, usually indentible.

•   Anal fissure.

Abnormal anal tone. A rectal examination is normally unnecessary unless child fails to responds to initiation of simple treatment, except in infancy when anal stenosis should be considered.

Management

Investigations are usually not necessary. If an organic cause is suspected consider: FBC; coeliac antibody screen; thyroid function tests; serum Ca²⁺; RAST testing; AXR; bowel transit studies (older child); rectal biopsy (for Hirschsprung’s disease); anal manometry; spinal imaging (neurological cause).

Prognosis

The vast majority of children can be ‘cured’ by an enthusiastic and sympa-thetic paediatrician with complete evacuation of any stool

masses, main-taining soft stools, and defaecation training. Many children need long term therapy. Do not underestimate the misery that this condition can inflict on both the child and family.