Constipation in Childhood

Constipation in children is a common problem and is often accompanied by parental anxiety. It is typically characterised by infrequent bowel evacuations, large stools and difficult or painful evacuation. It accounts for some 25% of paediatric gastroenterologists work and is also one of the 10 most common problems seen by general paediatricians. It is important to define the terms used as they inform diagnosis. The diagnosis in turn identifies the most appropriate management strategy. It is very important to make the diagnosis and start treatment. This is particularly because chronic constipation can lead to progressive faecal retention, rectal distension and loss of sensory and motor function.¹

Attempts have been made to define terms more precisely. There is something of lack of consensus on the meaning of words used for common defaecation problems. It is important to distinguish the normal from the abnormal. Frequency of bowel action reduces on average from 4x per day in early childhood to about once per day by age 4, by which age most (98%) of children are toilet trained.² Some terms regarded as imprecise such as soiling and encopresis have been replaced by the term incontinence.The following terms are recommended by the Paris Consensus on Childhood Constipation Terminology Group in 2005 and they inform the diagnostic criteria.³In practice there are still children who have symptoms not adequately described by these terms.⁴

• Constipation in children from whatever cause is very common worldwide and 90-95% of constipation is functional. In a systematic review of the literature to assess prevalence, incidence and natural history in functional constipation⁵
  • Prevalence ranged from 0.7% to 29.6%
  • Prevalence rates were similar in boys and girls
  • Age of highest prevalence could not be identified
  • Socioeconomic factors were not found to be associated
  • Further studies using newer diagnostic criteria were called for
• Most children with constipation are developmentally normal. It is seen commonly in:
  • Infants at weaning
  • Toddlers acquiring toilet skills
  • School age
• Often psychosocial factors may be involved or suspected. They may precede or maintain the constipation.⁶

• History. In addition to general history (past medical history, school and social history and family history) the parent and child should be specifically questioned about the constipation. Parents can mistake incontinence for diarrhoea. In infants under 6 months straining and crying for 10 minutes before passage of stools is caused by dyschezia (painful or difficult defaecation which resolves spontaneously) and may be mistaken for constipation. Specific questions should cover:
  • The frequency of defaecation
  • Consistency of stools-this may include use of the Bristol stool form chart⁷
  • Episodes of faecal incontinence
  • Pain on defaecation
  • Whether stools block the toilet
  • Any associated behaviour
  Any pain on defaecation is likely to lead to withholding. Toddlers and older children get better at withholding.
• Examination. This should include:
  • Palpation of the abdomen for faecal mass
  • Inspection for anal stenosis or ectopia
  • Look for sacral abnormalities
  • Rectal examination is not routinely necessary or required
  • Routine radiography is not recommended

It is important to distinguish organic causes from the much more common functional causes. Many of the organic causes will present in the first few weeks of life.
The evaluation of constipation with or without soiling should begin with careful history and physical examination.

Organic causes of constipation

Organic causes of constipation and diagnosis, further investigations or tests include:¹⁰

• Anorectal malformations:
  • Physical examination. Careful inspection of the perineum in any baby with constipation:
    • Is the anus in correct position relative to vulva or scrotum?
    • Careful digital rectal examination with well lubricated fifth finger is advocated by some (detect stricture, assess volume and hardness of rectal stool)⁴
• Anal fissure. This is common and associated with painful defaecation. Passage of blood and sentinel pile on the anterior anus are characteristic.⁴
• Rectal prolapse. This may be caused for example by chronic straining and constipation, disorders of sacral nerve innervation and chronic diarrhoea.⁴
• Hirschsprung's disease. This usually presents early (as delay in passing meconium, failure to thrive etc) well inside the first month. However rarely it can present late. Diagnosis is by:
  • Rectal biopsy-the test of choice
  • Anorectal manometry
  • Barium enema
• Neurenteric problems:
  • Colonic motility-the test of choice
  • Colonic transit
  • Possibly rectal biopsy
• Spinal cord problems:
  • Physical examination
  • Magnetic resonance imaging- the investigation of choice
  • Possible anorectal manometry
• Pelvic floor dyssynergia:
  • Anorectal manometry-the test of choice
• Metabolic or systemic disorders:
  • Hypothyroidism-thyroid function tests
  • Coeliac disease-tests for coeliac
  • Hypocalcaemia-Calcium
  • Cystic fibrosis-Sweat test
• Toxic:
  • Lead levels, toxicology screen
• Cow's milk allergy:
  • Elimination diet
  • Allergy testing

Functional causes of constipation

Chronic constipation and other types of functional constipation:

• History and physical examination are most important in the assessment and further tests are rarely necessary
• Further investigations are recommended occasionally in chronic constipation and always in non-retentive faecal incontinence. Specifically:
  • Radiology (Kidneys, ureter, bladder)
  • Colonic transit

History and examination are most important to make a diagnosis and should determine whether further investigations are required. The selection of investigations can be appreciated from the differential diagnoses above. Extensive investigations are not usually required.

This section is aimed at the management of functional constipation. The aims are to remove faecal impaction, restore bowel habit (with soft stools passed without pain), self toileting and passing of stools in appropriate places.

Management plans

Guidelines are a synthesis of clinical experience, evidence and consensus.¹¹There have been attempts to devise clear guidelines for the management of childhood constipation.⁴ There is a lack of robust evidence to inform the guidelines because research in this area is difficult.⁴

The following are important:
• Establishing rapport. This should take account of:
  • Anxiety of parent and child
  • Attitudes of guilt or blame
  • Inappropriately coercive toilet training
  • Social consequences (for example faecal incontinence in older children)
  The clinician should take a positive approach which is sympathetic, non-accusatory and with careful explanations and continued involvement and follow-up.
• Disimpaction.Retained faeces should be cleared from the rectum:
  • Rectal treatments should be avoided in children (suppositories, enemas, manual evacuation)
  • Mineral oil or polyethylene glycol 3350 (PEG) (1-1.5 g/kg/day for 3 days) can be effective^{1 12}
  • Glycerol suppositories may be used in infants
  • Bisacodyl suppositories may be used in older children
• Maintenance therapy. This may incorporate:
  • Dietary advice, including intake of fluids and fibre
  • Use of bowel charts and diary for objective record
  • Regular laxatives over months or even years, preferably osmotic (PEG or lactulose) titrated to maintain soft formed stool
  • Avoid stopping and starting treatment causing intermittent impaction
  • Avoid prolonged use of stimulant laxatives (causes atonic colon and hypokalaemia)
  • Use stimulant laxatives intermittently only to avoid impaction
• Modification of behaviour. Behavioural principles are useful in management. Specific behaviour modification techniques can be employed in in specialist clinics. In general:
  • Encourage regular, unhurried toileting
  • Encourage use of reward systems for successful use of the toilet
  • Encourage linkage of diary to reward system
• Incontinence. Dealing with this requires:
  • Explanation to parent and child of involuntary nature of this
  • Encouragement of regular toileting
  • Involvement of school nurse if possible to help with toileting and teacher education
  There is no good evidence for psychological interventions despite some associations between incontinence and psychological problems.¹¹

Available treatments

Evidence for effectiveness of treatments is weak.¹¹ The following agents are used:

• Osmotic laxatives:
  • No RCTs comparing use with placebo
  • No significant difference in lacitol versus lactulose in stool frequency or consistency
  • More abdominal pain and flatulence with lactulose than lacitol has been reported¹¹
  • One RCT shows PEG more successful than lactulose with fewer adverse effects¹³
• Stimulant laxatives:
  • Cochrane review shows insufficient evidence for efficacy of stimulant laxatives¹⁴
  • No placebo controlled randomised trials of the effects of stimulant laxatives in children were found¹¹
• Biofeedback and psychological interventions. Evidence for benefit is lacking.¹¹ 50% of constipated children contract rather than relax the external sphincter during defaecation attempts and although biofeedback can change this behaviour, there is no additional outcome benefit over conventional long term and adequate laxative treatments.^{15 16}
• Increasing dietary fibre. Evidence is lacking.¹¹ One double blind, randomised crossover study reports benefit from fibre and suggests continued use in the diet of constipated children with or without encopresis.¹⁷

Indications for referral

Specialist assessment is indicated if:

• Organic cause suspected
• Treatment unsuccessful
• Management is complex

When an organic cause is suspected the GP can arrange for initial tests (such as inflammatory markers, thyroid function, calcium, tests for coeliac disease). Some specialists measure colonic transit time to differentiate:

• Soiling with normal transit time from
• Constipation and delayed transit time (worse outcomes)

Surgery is required rarely for the most severe cases of chronic constipation and overflow soiling. It can be important in intractable cases.⁴ Botulinum toxin has been used for short aganglionic segments of bowel and to provide temporary weakening of the sphincter.⁴

Failure to correct functional constipation may lead to problems. For example the following may arise:

• Faecal impaction
• Chronic constipation
• Megacolon (may predispose to, or result from, constipation)
• Rectal prolapse
• Anal fissure
• Faecal soiling
• Psychological effects

Long term follow up studies of children referred to a specialist clinic under age 5 showed 50% recovery within 1 year, 65-70% recovery within 2 years with the remaining 30% or so requiring long term laxatives or continuing to soil.⁶ In another study 30% of children continued to have severe constipation beyond puberty.¹⁸ Obviously results from earlier treatment of less severe cases in general practice should be better than this.