The following are common causes of blood in the stool in children: 1, anal fissure Most often seen in infants and young children around 2 years old, blood in the stool is characterized by a small amount of drops of fresh blood, dry and hard stools, accompanied by painful defecation, so the child is reluctant to defecate, thus aggravating the symptoms. Treatment is mainly to maintain local cleanliness, oral laxatives, increase fiber-rich food and change stool habits. 2, acute intussusception This is the most common acute abdominal disease in children, is also a common cause of blood in the stool. Most commonly seen in children under 2 years of age, especially in infants 4-10 months. The symptoms of the child are mainly blood in the stool, jam-like stool, and crying and vomiting due to the accompanying abdominal pain. 3. Acute necrotizing enterocolitis is an acute hemorrhagic necrotizing inflammatory disease confined to the small intestine, with lesions mainly in the jejunum or ileum. The disease often develops in summer and autumn, may have a history of unclean food, the onset of acute abdominal pain, mostly from the umbilicus or the upper midsection, the pain is paroxysmal colic or persistent pain with paroxysmal intensification. 4, intestinal polyps is a common cause of pediatric blood in the stool, mostly seen in children aged 3-6 years. Blood in the stool is characterized by the presence of fresh blood at the end of defecation, small, painless, and not mixed with stool. Mucus-purulent stools can occur when secondary infection occurs. Most intestinal polyps in children are juvenile polyps, which are actually misshapen tumors and rarely become malignant.