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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Functional (idiopathic) constipation accounts for >95% of cases in children >1 year
- Triggers: weaning, toilet training, starting school, painful defecation leading to withholding cycle
- Red flags for organic cause (Hirschsprung): delay in passing meconium >48 h, onset from birth, empty rectum on DRE, failure to respond to adequate laxatives, ribbon stools, abdominal distension from birth
- First-line: macrogol (Movicol Paediatric Plain) — both for disimpaction and maintenance
- Disimpaction: escalating dose of Movicol over 1–2 weeks until soft stools. Then maintenance dose for months-years
- Behavioural: regular toileting routine (sit on toilet after meals), praise, adequate fibre and fluid, avoid blame
Overview
Constipation in children is defined as infrequent bowel movements (less than 3 per week), hard stools, painful defecation, or faecal impaction. Functional constipation is by far the most common cause, typically developing when a child experiences a painful stool and subsequently withholds, creating a vicious cycle. Overflow soiling (encopresis) occurs when liquid stool leaks around impacted faeces — this is NOT diarrhoea and is NOT deliberate. Treatment requires sustained laxative therapy (often months to years) and behavioural management.
Epidemiology
Constipation accounts for up to 25% of paediatric gastroenterology referrals and 3% of general paediatric outpatient visits. It affects approximately 5–30% of children depending on definition. Peak presentations coincide with weaning (6–12 months), toilet training (2–3 years), and starting school (4–5 years). Functional constipation is equally common in boys and girls in early childhood. Encopresis is more common in boys.
Clinical Features
Symptoms
Infrequent stools (<3 per week), large or hard stools
Pain and straining on defecation — child may cry, hold on, or refuse to sit on toilet
Overflow soiling (encopresis) — involuntary leaking of liquid stool around faecal impaction
Abdominal pain — often colicky, relieved by passing stool
Poor appetite
Delay in passing meconium beyond 48 hours (Hirschsprung)
Signs
Palpable faecal mass in left iliac fossa or suprapubically
Abdominal distension
Perianal soiling
Anal fissure (cause and consequence of constipation)
Loaded rectum on DRE (if performed — not routine)
EMPTY rectum on DRE despite constipation (Hirschsprung)
Investigations
First-line
Clinical diagnosisHistory and examination are sufficient in most cases. No routine investigations needed for functional constipation
Second-line
Abdominal X-rayNOT routine — only if diagnostic uncertainty (can show faecal loading but does not change management)
TFTsIf clinical concern for hypothyroidism
Coeliac screenIf faltering growth or other suggestive features
Specialist
Suction rectal biopsyIf Hirschsprung suspected — absent ganglion cells confirms diagnosis
Transit studyRarely needed — for refractory cases to differentiate slow-transit from functional outlet obstruction
1
Disimpaction (if impacted)
- Movicol Paediatric Plain: escalating dose regimen over 1–2 weeks (day 1: 2 sachets, increase by 2 sachets every 2 days up to maximum for age)
- If Movicol not tolerated: stimulant laxative (sodium picosulfate or senna)
- Consider adding stimulant (senna or sodium picosulfate) alongside Movicol
- Target: child passing soft stools daily without overflow
2
Maintenance
- Movicol Paediatric Plain: adjust dose to produce soft formed stools (typically 1–4 sachets daily)
- Continue for MONTHS to YEARS — do not stop too early (relapse rate very high)
- Gradually reduce dose over weeks-months once regular soft stool pattern established
- Add stimulant laxative if needed (senna, sodium picosulfate)
3
Behavioural management
- Regular toilet sitting after meals (utilise gastrocolic reflex) for 5–10 minutes
- Positive reinforcement: star charts, praise — never punish for soiling
- Feet must be supported on a step (knees above hips)
- Adequate fluid and fibre intake (but NOT as primary treatment — laxatives are first-line)
- Education: soiling is NOT deliberate — it is overflow. The child cannot control it
4
Referral criteria
- Failure to respond to adequate first-line treatment after 3–6 months
- Suspected Hirschsprung disease
- Safeguarding concerns (constipation can be associated with sexual abuse)
- Significant psychological impact
Complications
- Overflow soiling: Liquid stool leaking around impaction — socially devastating for the child
- Anal fissure: Painful — reinforces withholding cycle
- Recurrent UTI: Constipation is the most common correctable risk factor
- Psychological impact: Shame, bullying, school avoidance, low self-esteem
- Megarectum: Chronic distension leads to loss of sensation — prolonged treatment needed
UKMLA Exam Tips
- 1Overflow soiling is NOT diarrhoea — it is liquid stool leaking around impacted faeces. Treatment is DISIMPACTION, not anti-diarrhoeals
- 2Movicol Paediatric Plain is first-line for both disimpaction and maintenance per NICE CG99
- 3Diet and fluids alone are NOT adequate treatment — laxatives are first-line
- 4Continue maintenance laxatives for MONTHS to YEARS — stopping too early causes relapse
- 5Hirschsprung red flags: onset from birth, delayed meconium, empty rectum on DRE, failure of adequate laxatives
- 6Functional constipation: rectum is LOADED. Hirschsprung: rectum is EMPTY
practicetest your knowledge on constipation in childrenApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — paediatrics and beyond.
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