Definition & Key Features

• Definition: Idiopathic constipation is constipation that cannot be explained by any anatomical, physiological, radiological, or histological abnormalities. It is defined by the presence of at least two key clinical findings for which a positive diagnosis can be made.
• Pathophysiology: A vicious cycle often develops where painful defecation (due to hard stools or anal fissure) leads to withholding behaviour. This results in further stool hardening, accumulation, and stretching of the rectum, reducing sensation and perpetuating the cycle.
• Hallmark Features:
  • Infrequent bowel movements (<3 complete stools per week).
  • Passage of hard, large stools (Bristol Stool Form Scale type 1 or 2) or “rabbit droppings”.
  • Overflow soiling/encopresis (loose, smelly stool passed without sensation).
  • Retentive posturing (straight-legged, tiptoeing, back-arching) to avoid defecation.
  • Straining.
• Typical Signs/Symptoms:
  • Abdominal pain, discomfort, and distension that waxes and wanes.
  • Poor appetite, which improves after passing a large stool.
  • Lack of energy, irritability, or general malaise.
  • Foul-smelling wind and stools.
• Complications if Untreated:
  • Chronic constipation (lasting >8 weeks).
  • Anal fissures.
  • Faecal impaction with overflow soiling.
  • Significant social, psychological, and educational consequences.

Epidemiology & Risk Factors

• Prevalence: Affects 5% to 30% of the paediatric population. More than one-third of cases become chronic.
• Risk Factors:
  • Pain: Previous painful defecation is a critical factor.
  • Dietary/Fluid: Insufficient fluid or fibre intake. Changes in diet (e.g., weaning, changing formula).
  • Illness: Fever, dehydration.
  • Psychological/Behavioural: Toilet training issues, fears, and phobias.
  • Social: Major life events (moving house, starting nursery/school).
  • Medications: Drugs that can cause constipation.
  • Familial History: Family history of constipation.
  • Comorbidities: Increased prevalence in children with physical disabilities (e.g., cerebral palsy) and neurodevelopmental disorders (e.g., Down’s syndrome, autism).

Clinical Presentation & Diagnosis

Diagnostic Criteria

A diagnosis of constipation is made if two or more of the following findings are present:

• For all ages:
  • Fewer than three complete stools per week (Bristol Stool Form Scale type 3 or 4). This does not apply to exclusively breastfed babies after 6 weeks of age.
  • Overflow soiling.
  • “Rabbit droppings” (type 1 stools).
  • Large, infrequent stools that can block the toilet.
  • Previous episodes of constipation or anal fissure.
  • Straining.
  • Painful bowel movements or bleeding associated with hard stools.
• Additionally for children <1 year: Distress on stooling.
• Additionally for children >1 year:
  • Retentive posturing.
  • Poor appetite improving with passage of large stool.
  • Waxing and waning abdominal pain.

Red Flags (Indicating Urgent Referral)

If any red flag is present, do not treat for constipation. Refer urgently to a healthcare professional with relevant experience.

• From History:
  • Reported from birth or the first few weeks of life.
  • Delayed passage of meconium (>48 hours after birth in a term baby).
  • ‘Ribbon stools’.
  • Abdominal distension accompanied by vomiting.
  • Previously unknown or undiagnosed weakness in legs or locomotor delay.
• From Physical Examination:
  • Gross abdominal distension.
  • Abnormal perianal area: fistulae, bruising, multiple deep fissures, tight or patulous anus, anteriorly placed anus, absent anal wink.
  • Abnormal spine/lumbosacral region: asymmetry/flattening of gluteal muscles, sacral agenesis, discoloured skin, naevi, hairy patch, lipoma, central pit (dimple where you cannot see the bottom), scoliosis.
  • Abnormal neuromuscular signs: deformity in lower limbs (e.g., talipes), abnormal tone, strength, or reflexes unexplained by an existing condition.

Differential Diagnoses & Specific Situations

• Faltering Growth: If present, treat for constipation and test for coeliac disease and hypothyroidism.
• Child Maltreatment: If history or examination raises concerns, treat for constipation and follow local safeguarding procedures/NICE guideline on child maltreatment.
• Perianal Streptococcal Infection: If evident on examination, treat the infection alongside the constipation.

Investigations

• Digital Rectal Examination (DRE):
  • Should only be undertaken by healthcare professionals competent to interpret features of anatomical abnormalities or Hirschsprung’s disease.
  • Do not perform in children >1 year with a red flag; refer them urgently instead.
  • Refer infants <1 year urgently if they do not respond to optimum treatment within 4 weeks for a competent DRE.
• Investigations NOT Recommended for Diagnosis:
  • Plain abdominal radiograph.
  • Abdominal ultrasound.
  • Gastrointestinal endoscopy.
  • Anorectal manometry (to exclude Hirschsprung’s disease).
  • Transit studies.
  • These may be considered by specialist services for intractable constipation.
• Rectal Biopsy: Do not perform unless clinical features of Hirschsprung’s disease are present (e.g., delayed meconium, constipation from birth, family history, chronic distension with vomiting, faltering growth).

Initial Management

1. Assessment for Faecal Impaction

• Assess all children with constipation for impaction using history (overflow soiling) and physical examination (faecal mass palpable abdominally).
• If not impacted, proceed directly to maintenance therapy.

2. Disimpaction (if impacted)

• First-Line Drug: Macrogol 3350 combined with potassium chloride, sodium bicarbonate, and sodium chloride (also known as Polyethylene glycol 3350 + electrolytes), using an escalating dose regimen.
  • Note: Not all macrogol preparations are licensed for all ages; check individual product licenses.
• Patient Education: Inform families that treatment can initially increase soiling and abdominal pain.
• Escalation:
  • If disimpaction is not achieved after 2 weeks of polyethylene glycol, add a stimulant laxative (e.g., senna, sodium picosulfate).
  • If polyethylene glycol is not tolerated, substitute with a stimulant laxative. If stools remain hard, this can be combined with an osmotic laxative (e.g., lactulose).
• Monitoring: Review the child within 1 week.

3. Maintenance Therapy

• Start: Begin immediately after successful disimpaction.
• First-Line Drug: Polyethylene glycol 3350 + electrolytes.
  • Dosage: Adjust dose according to symptoms and response. A typical starting dose is half the final disimpaction dose.
• Escalation:
  • If polyethylene glycol alone is insufficient, add a stimulant laxative.
  • If polyethylene glycol is not tolerated, substitute with a stimulant laxative. If stools are hard, add lactulose or docusate.
• Duration: Continue at maintenance dose for several weeks after a regular bowel habit is established (may take several months). Do not stop medication abruptly. Gradually reduce the dose over months in response to stool consistency and frequency. Some children require treatment for years.

4. Non-Pharmacological Measures

• Use in combination with laxatives, not as first-line treatment alone.
• Behavioural Interventions:
  • Scheduled, non-punitive toileting routines.
  • Use of a bowel diary.
  • Encouragement and reward systems.
• Dietary Advice:
  • Advise a balanced diet with adequate fibre from fruit, vegetables, high-fibre bread, baked beans, and wholegrain cereals.
  • Do not recommend unprocessed bran (can cause bloating and reduce micronutrient absorption).
• Fluid Advice: Advise adequate fluid intake. Daily recommendations for water from drinks are:
  • 7–12 months: 600 ml
  • 1–3 years: 900 ml
  • 4–8 years: 1,200 ml
  • Boys 9–13 years: 1,800 ml
  • Girls 9–13 years: 1,600 ml
  • Boys 14–18 years: 2,600 ml
  • Girls 14–18 years: 1,800 ml
• Physical Activity: Encourage daily physical activity tailored to the child’s age and ability.

Further Management & Escalation

Second-Line / Specialist Interventions

• Rectal Medications (for disimpaction):
  • Use only if all oral medications have failed and with family consent.
  • First Choice: Sodium citrate enemas.
  • Second Choice: Phosphate enemas, administered only under specialist supervision in a hospital/clinic setting, if all oral medications and sodium citrate enemas have failed.
• Manual Evacuation: Only under anaesthesia if optimum oral and rectal medication treatment has failed.
• Dietary Trial: A cow’s milk exclusion diet should only be started on the advice of a specialist.
• Psychological Interventions:
  • Do not use biofeedback.
  • Do not routinely refer to psychology/CAMHS unless there is a specific indication that the child is likely to benefit.
• Surgical Options: Refer children with unresolved symptoms despite optimum management to a paediatric surgical centre to assess suitability for an antegrade colonic enema (ACE) procedure.

Referral Criteria

• Urgent Referral:
  • Any child or young person with “Red Flags” on history or examination.
  • Infants <1 year who fail to respond to 4 weeks of optimum treatment (for expert DRE).
• Routine Referral to a specialist/practitioner with expertise:
  • Children who do not respond to initial treatment within 3 months.
  • For consideration of specialist investigations (radiograph, ultrasound etc.) in intractable constipation.
  • For advice on starting a cow’s milk exclusion diet.
• Surgical Referral:
  • Children with intractable constipation despite optimum medical management, to assess for an ACE procedure.

Follow-up & Safety Netting

• Frequency of Follow-up: Reassess frequently during treatment, especially maintenance therapy. The frequency should be tailored to individual needs, ranging from daily to every few weeks.
• Monitoring: Use the Bristol Stool Form Scale to monitor stool consistency and frequency. Ensure the child does not become re-impacted. The ERIC Toilet Tool Wallchart could be useful
• Patient Education & Support:
  • Provide verbal information supported by written/online resources about the condition, medication, what to expect, toileting strategies, and the importance of continuing treatment (leaflets are available from the NHS and ERIC).
  • Inform families that resolving constipation is a long process, often taking many months.
  • Provide a point of contact with specialist healthcare professionals, including school nurses, for ongoing support.
• Warning Signs for Reassessment: Advise families to seek review if symptoms worsen, soiling returns or increases, or other concerning features develop.

Key Points to Remember

• Positive Diagnosis: Diagnose constipation clinically if ≥2 specific features are present.
• Exclude Red Flags: Always screen for red flags in the history and examination; their presence warrants urgent referral, not treatment for idiopathic constipation.
• Disimpact First: If faecal impaction is present, treat this first with an escalating dose of polyethylene glycol 3350 + electrolytes before starting maintenance therapy.
• First-Line is PEG: Polyethylene glycol 3350 + electrolytes is the first-line drug for both disimpaction and maintenance.
• Combine Therapies: Use laxatives in combination with behavioural, dietary, and fluid advice. Diet alone is not first-line treatment.
• Treatment is Long-Term: Warn families that treatment may be required for many months to years. Do not stop laxatives abruptly; wean gradually once a regular pattern is well established.
• No Routine Investigations: Do not use X-rays, ultrasounds, or other tests to diagnose idiopathic constipation in primary care.
• Know When to Refer: Refer urgently for red flags. Refer to a specialist if there is no response to treatment within 3 months.

This MedDigest summary is intended for educational purposes only and should not be used for clinical purposes. It is an independent resource, prepared by MedDigest, to offer an accessible overview of information drawn from the NICE guidelines. The original NICE content is © Crown copyright and is used under the Open Government Licence v3.0. While MedDigest strives for accuracy in its educational summaries, this content has not been reviewed or produced by NICE. For comprehensive and definitive recommendations, please always refer to the complete NICE guidelines.

References

NICE (2017) Constipation in children and young people: diagnosis and management. https://www.nice.org.uk/guidance/cg99