Constipation in children
Exam Tips
- In OSCEs, diagnose constipation clinically from history + exam; do not request routine abdominal X-ray.
- Always screen for red flags first: delayed meconium (>48 h in term infant), onset from birth/early weeks, gross distension with vomiting, neurological/spinal/perianal abnormalities.
- Faecal impaction is suggested by severe constipation history + overflow soiling + palpable faecal mass.
- A key trap: overflow soiling indicates severe constipation, not simple diarrhoea.
- Remember common stool frequencies by age and use Bristol stool descriptors when presenting findings (see Bristol Stool Form Scale figure in standard paediatric exam resources).
Definition
Constipation in children is a clinical syndrome of infrequent, difficult, or painful defecation, typically with hard stools and often associated with stool withholding behaviour. In practice, diagnosis is symptom-based (usually two or more typical features), and chronic constipation is generally defined as symptoms persisting for more than 8 weeks; most cases are functional (idiopathic) rather than due to organic disease.
Pathophysiology
Most paediatric constipation is functional and begins with a trigger (for example painful stool, fissure, toilet-training stress, illness, diet/fluid change). The child then withholds stool, increasing colonic water absorption and producing larger, harder stools; repeated withholding causes rectal dilatation (megarectum), reduced rectal sensation, and weaker urge perception. This creates a self-perpetuating cycle of painful defecation, further retention, faecal loading, and possible overflow soiling from liquid stool passing around impacted faeces.
Risk Factors
- Previous painful defecation or anal fissure
- Toilet-training difficulties (peak around 2-3 years)
- Low fluid intake and low dietary fibre intake
- Psychosocial stressors (starting nursery/school, family disruption, phobias)
- Physical inactivity or impaired mobility (for example cerebral palsy)
- Neurodevelopmental conditions (for example autism spectrum disorder, Down syndrome)
- Family history of constipation
- Drugs such as opioids and sedating antihistamines
- Recent acute illness or fever
Clinical Features
Symptoms
- Fewer than 3 complete stools per week (except some thriving exclusively breastfed infants)
- Hard large stools, sometimes toilet-blocking in older children
- Type 1 'rabbit dropping' stools on Bristol Stool Form Scale
- Painful stooling, distress, straining, or anal pain
- Bleeding with passage of hard stool
- Overflow soiling in toilet-trained children (often loose, offensive, passed without awareness)
- Poor appetite that improves after passing a large stool
- Waxing and waning abdominal pain related to stool passage
- Withholding/retentive posturing (tiptoeing, straight legs, back arching)
Signs
- Palpable faecal mass on abdominal examination (especially with impaction)
- Abdominal distension (mild in functional disease; marked distension is concerning)
- Perianal fissure or irritation
- Otherwise normal growth, neurology, spine/lumbosacral and perianal anatomy in idiopathic constipation
- Red-flag signs: abnormal anus, absent anal wink, lower-limb neuromuscular abnormalities, lumbosacral cutaneous markers, gross distension with vomiting
Investigations
Management
Lifestyle Modifications
- Explain stool-withholding cycle and that soiling is often overflow, not deliberate behaviour.
- Establish regular toileting routine: sit on toilet after meals (gastrocolic reflex), feet supported, relaxed posture, reward system.
- Optimise age-appropriate fluid intake and balanced fibre intake; avoid punitive toilet practices.
- Provide safety-netting and follow-up; early treatment improves long-term outcomes.
- Address triggers: pain, school toilet avoidance, psychosocial stress, and constipation-inducing medicines where possible.
Pharmacological Treatment
Osmotic laxative first-line (disimpaction then maintenance)
- Macrogol 3350 with electrolytes (paediatric sachets): disimpaction 1-5 years: Day 1: 2 sachets, Day 2: 4, Day 3: 6, Day 4-7: 8 sachets/day; 5-11 years: Day 1: 4, Day 2: 6, Day 3: 8, Day 4-7: 10 sachets/day
- Macrogol 3350 with electrolytes maintenance: start around 1 sachet daily (age 1-11 years), titrate to produce soft regular stool
Give each sachet in recommended water volume and titrate to effect; common adverse effects are bloating, flatulence, abdominal discomfort. Avoid if intestinal obstruction, perforation, or severe inflammatory bowel conditions are suspected.
Add stimulant laxative if response inadequate to macrogol
- Senna at night: 2-6 years usually 2.5-5 mg, 6-11 years 5-10 mg, 12-17 years 5-15 mg once daily (formulation-specific)
- Sodium picosulfate once daily: 1 month-3 years 2.5 mg, 4-10 years 2.5-5 mg, over 10 years 5-10 mg
Useful when stool remains difficult to pass despite osmotic therapy. Counsel on abdominal cramps/diarrhoea. Avoid in suspected bowel obstruction; stimulant overuse can cause fluid/electrolyte disturbance.
Alternative/additional osmotic agent
- Lactulose: 1 month-11 years 2.5-10 mL twice daily (adjust to response); 12-17 years typically 15-45 mL daily then maintenance 10-25 mL daily
Can be used if macrogol not tolerated/available. Adverse effects include bloating and flatulence. Contains sugars; use caution in galactosaemia and consider dental advice with prolonged use.
Rectal therapy (select cases)
- Glycerol suppository (infant/child): occasional rescue treatment for hard rectal stool
Reserve for specific situations (for example distal hard stool when oral plan insufficient). Invasive interventions can increase anxiety; avoid repeated unsupervised use.
Complications
- Anal fissure with recurrent pain-withholding cycle
- Faecal impaction and overflow soiling
- Megarectum
- Haemorrhoids
- Rectal prolapse
- Volvulus (rare, severe)
- Urinary symptoms (for example enuresis/recurrent UTI from pelvic stool loading)
- Psychological, behavioural, and social impact (embarrassment, school avoidance)
Prognosis
Prognosis is variable but generally improves with early, sustained treatment and family engagement. Around half of children may come off laxatives by 6-12 months, while a substantial minority require longer therapy; delayed treatment is associated with prolonged symptoms, and some continue to have bowel problems into adolescence/adulthood.
Sources & References
🏥BMJ Best Practice(4)
✅NICE Guidelines(1)
- Constipation in children[overview]
📖Textbook References(5)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1768)[context]
- Emergencies in - Obstetrics and Gynaecology, Second Edition (Stergios K. Doumouchtsis, S. Arulkumaran) (Z-Library).pdf(pp. 33)[context]
- Emergencies in - Obstetrics and Gynaecology, Second Edition (Stergios K. Doumouchtsis, S. Arulkumaran) (Z-Library).pdf(pp. 33)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 1268)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 1268)[context]