A 4-year-old boy has reduced bowel frequency (once in 5 days) and hard stools for 6 months. He refuses to pass stools in the potty and stiffens his body when he feels the urge. He is well grown; examination reveals a large faecal mass in the lower abdomen. What is the most likely diagnosis?

Answer: E. Functional constipation

Functional constipation

This well-grown 4-year-old with chronic hard, infrequent stools, stool-withholding behaviour (stiffening, refusing the potty) and a palpable faecal mass has functional constipation - the cause in over 95% of children with constipation.

Why functional, not organic

• The child is well grown with no red flags.
• The history of withholding (a fear-of-pain cycle) is characteristic of functional constipation.
• A faecal mass reflects stool retention and impaction.

The withholding cycle

1. A painful or hard stool leads the child to withhold.
2. Retained stool becomes harder and larger.
3. The next motion is more painful, reinforcing withholding - and a faecal mass and overflow soiling can develop.

Organic causes to exclude (when red flags present)

Hirschsprung's disease, hypothyroidism, hypercalcaemia, coeliac disease, and spinal/neurological problems - all rare, and sought only if red-flag features appear.