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Functional constipation in children
Most constipation in children is functional — a cycle of painful defecation, withholding and ever-harder stool; the diagnosis is clinical by Rome IV, without tests, and treatment is disimpaction followed by months of PEG, together with toilet habits — unless there are red flags such as delayed meconium pointing to Hirschsprung disease.
Why it matters in the exam
The question describes a 4-year-old with infrequent, painful stools, a withholding "dance", soiling of the underwear (which looks like diarrhoea but is leakage around the stool) and a faecal mass in the abdomen. The answer is functional constipation: explanation for the parents, disimpaction (high-dose PEG 1–1.5 g/kg per day for 3–6 days, or enemas), then maintenance PEG at about 0.4 g/kg per day for at least two months — and at least one month after symptoms resolve — with gradual weaning.
By Rome IV, two or more of the following are needed: two or fewer stools a week, soiling at least once a week in a toilet-trained child, withholding behaviour, painful or hard stools, a large faecal mass in the rectum, and large-diameter stools that block the toilet — for one month in a toddler and for two months from age 4. An abdominal X-ray is not used for diagnosis. Extra fibre and fluid beyond normal intake are not proven to help.
The red flags: onset in the first month of life, meconium after 48 hours, ribbon-like stools, a distended abdomen with vomiting, failure to thrive, findings over the lower back (a dimple, a hair tuft), weak leg reflexes and an "explosive" stool after rectal examination. These point to Hirschsprung disease (rectal suction biopsy showing absent ganglion cells), a spinal problem or a metabolic disease. In resistant constipation test thyroid function, coeliac serology and calcium, and in an infant consider cow's milk allergy.
Key points
- Most constipation in children is functional.
- Clinical diagnosis by Rome IV, without X-ray.
- Disimpaction with PEG 1–1.5 g/kg per day, and maintenance about 0.4 g/kg per day for at least two months.
- Red flags: onset in the first month, delayed meconium, distended abdomen.
- Hirschsprung disease — rectal suction biopsy.
Summary table
| Situation | Clue | Work-up | Treatment |
|---|---|---|---|
| Functional constipation | Infrequent painful stools, withholding, soiling | Clinical (Rome IV), no X-ray | PEG disimpaction and maintenance 0.4 g/kg per day for at least two months |
| Overflow soiling | Loose "diarrhoea" around hard stool | Examination: faecal mass | Disimpaction and maintenance; no antidiarrhoeals |
| Hirschsprung disease | Meconium after 48 hours, distended abdomen, explosive stool after examination | Rectal suction biopsy; contrast enema | Surgery; risk of enterocolitis |
| Spinal cause | Lower back finding, weak reflexes, urinary problems | Spinal MRI | Treat the cause |
| Systemic cause | Fatigue, failure to thrive, thirst | TSH, coeliac serology, calcium | Treat the cause |
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Sources
- ESPGHAN/NASPGHAN Evidence-Based Recommendations: Evaluation and Treatment of Functional Constipation in Infants and Children, 2014 — Disimpaction and maintenance with PEG
- Rome IV Criteria for Childhood Functional Gastrointestinal Disorders, 2016 — Functional constipation criteria
- Nelson Textbook of Pediatrics, 22nd edition (2024) — Functional Constipation; Hirschsprung Disease
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.