Bloody or bloody stools in infants: After birth, the intestinal mucosa is challenged with numerous antigens (viruses, commensal microorganisms, dietary antigens) that can induce inflammation of the gastrointestinal tract, resulting in bloody stools. Visits for bloody stools account for 0.3% of pediatric emergencies. Most bloody stools in infants are benign, self-limiting disorders that can last for days to months, with recurrent, intermittent episodes. Determining whether there is bleeding: Routine stool testing is an essential step in verifying bleeding. 1. Blood resembling bright red: food coloring, children’s drinks, red candy, tomato skins, antibiotic syrup. 2, black stool: taking iron supplements, eating spinach, blueberries, grapes, licorice, etc. Occult blood test is a qualitative method to detect stool bleeding: redox method has false positive results, gold standard method removes false positive reactions and improves the accuracy of the test. Common diseases: 1, anal fissure: bright red blood attached to the surface of normal stool, wipe paper stained with blood. Mostly caused by constipation or excessive forceful wiping of the anus due to the number of bowel movements. 2. Colitis: diarrhea, urgency (feeling of urgency in the stool), nocturnal bowel movements, abdominal pain (paroxysmal crying). Caused by bacterial or viral infection. Routine stool examination and stool pathogenic examination (bacterial culture, virus detection) help in diagnosis. 3. Milk protein allergy: <6 months old infants with other manifestations such as anorexia, refusal of food or feeding difficulties, eczema or perianal rash, skin erythema, crying, etc., in addition to bloody or blood-stained stools. Milk avoidance-excitation test confirms the diagnosis: milk avoidance (choice of amino acid formula or deeply hydrolyzed formula) for 2-4 weeks and disappearance of symptoms. Return to normal formula symptoms reappear. 4. Juvenile polyps: Juvenile polyps are common under 3 years of age and rare under 1 year of age. No constipation symptoms, a small amount of bright red or dark red blood mixed in the stool or covering the surface of the stool. Barium enema examination has a positive rate of more than 80%. It can be removed by colonoscopy and colonoscopic electrocoagulation and electrosurgery. 5, hemorrhoids: rare in children and adolescents. 6, lactose intolerance: itself will not lead to bloody stools, but due to the number of stools, excessive force wipe the anus can lead to anal fissures.