See [RCH constipation](x-devonthink-item://BF7B87E7-B8F3-41EE-A57D-7459C0D17814) - anal fissures - dietary causes - functional constipation.  Much less common, but obviously more serious, causes of constipation include [[neonatal bowel obstruction|hirschsprung disease]], [[neonatal bowel obstruction]], and infantile botulism. - A visual inspection of the perineum and perianal area is important in detecting an anal fissure or dermatitis that may lead to painful defecation and retention of stool. - The presence of hard or large stools in the rectal vault supports the diagnosis of constipation. Laboratory tests and CT may be considered if the child’s presentation is atypical for constipation, but they should be performed only after a rectal examination.