What Causes Blood in an Infant’s Stool?

Blood in the stool of infants during infancy may arise from several causes: First, bacterial enteritis—affected infants may present with fever, vomiting, bloody stools, and mucus in the stool. Routine stool examination and stool culture can aid diagnosis. A positive result warrants antibiotic therapy and enhanced dietary hygiene. Second, local anorectal conditions such as hemorrhoids or anal fissures may cause rectal bleeding in infants. In such cases, blood typically coats the surface of the stool and commonly appears toward the end of defecation.

What Causes Blood in Infant Stool?

Pain and crying during defecation may also occur; digital rectal examination can assist in diagnosis. Third, systemic diseases—including hematologic disorders—may be responsible. For instance, infants with coagulation disorders may develop hematochezia. Intussusception—characterized by “currant-jelly”-like bloody stools—requires confirmation via abdominal ultrasound, particularly focusing on the periumbilical region. Therefore, when blood is observed in an infant’s stool, careful assessment of its characteristics (e.g., color, consistency, timing relative to defecation) and location is essential to identify and address the underlying cause.

The most common cause of hematochezia is gastrointestinal bleeding. Small-volume upper gastrointestinal bleeding may darken stool color; prolonged intestinal transit time results in tarry (melena) stools. In contrast, lower gastrointestinal bleeding—or massive upper gastrointestinal hemorrhage—typically presents as bright red or maroon blood mixed with or passed separately from stool.

In cases of infant constipation, excessive straining during defecation may cause anal lacerations and subsequent bleeding, with blood appearing separate from the stool. Regardless of the suspected cause, prompt medical evaluation is recommended to determine the etiology and initiate appropriate treatment. Additionally, clinicians should consider potential associations with food intolerance or food allergy.