In most children, constipation is functional and without evidence of a pathological condition. Functional constipation most commonly is caused by painful bowel movements, resulting in voluntary withholding of feces by a child. Toilet training, dietary changes, stressful events, illness, unavailability of toilets, or postponing defecation because the child is too busy can all lead to painful defecation, ultimately causing constipation.

A thorough history is an essential element in evaluating a child with constipation. Important information includes the time after birth of the first bowel movement, how the family defines the term constipation, duration of symptoms, the frequency of bowel movements, the consistency and size of the stools, whether defecation is painful, whether blood has been present on the stool or toilet paper, and if the child experiences abdominal pain. In infants, painful or difficult defecation may be indicated by straining and grunting, leg stiffening, and/or back arching.

History of fever, abdominal distention, anorexia, nausea, vomiting, weight loss, or poor weight gain may suggest an organic disorder. Bloody diarrhea in an infant with a history of constipation could be an indication of enterocolitis secondary to Hirschsprung disease. A psychosocial history is important to assess the family structure, the interactions the child has with peers, and the possibility of abuse. While constipation may be seen in sexually abused children, it is not diagnostic of abuse. Most sexually abused children do not have abnormal physical findings.

The physical examination should involve external examination of the perineum and perianal area with digital examination of the anorectum to assess perianal sensation, anal tone, the size of the rectum, and the presence of an anal wink. It is important to also determine the amount and consistency of stool and its location within the rectum. It is recommended that a test for occult blood in the stool be performed in all infants with constipation as well as in any child with symptoms suggestive of an organic disorder.

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