In a healthy child with constipation and no red flags, the most likely diagnosis is which of the following?

• A. Hirschsprung disease
• B. Diet modification
• C. Functional constipation
• D. Encopresis

Answer: (C)

Functional constipation is the most likely explanation when a healthy child has constipation without any red flags. This means the problem is functional (no structural or systemic disease) and driven by stool withholding, infrequent bowel movements, and often small or hard stools. The child’s growth and overall health are normal, which argues against a more serious condition.

Hirschsprung disease would raise red flags such as failure to pass meconium within the first days of life, bilious vomiting, progressive abdominal distension, or poor weight gain, which aren’t described here. Encopresis is fecal incontinence that can occur in the setting of chronic constipation; it’s a consequence rather than the initial diagnosis in a child who only presents with constipation. Diet modification is a management step, not a diagnosis, though increasing fiber and fluids can help functional constipation.