Causes of blood in stools in children: Blood in stools refers to the discharge of blood from the anus, and stools that are bright red, dark red, or tarry (black) in color become blood in stools. Blood in the stool is often indicative of bleeding in the lower gastrointestinal tract, especially in the colon and rectum. Blood in the stool and blood in the vomit are indicative of upper gastrointestinal bleeding. Common causes of blood in stool are as follows: 1, pediatric enteritis: mostly caused by invasive, virulent bacteria, may have blood, pus and blood stools, accompanied by diarrhea, fever. 2, intestinal polyps: to occur in the rectum and sigmoid colon is common. Blood in the stool is usually bright red blood covering the surface of the stool, and there may be polyp prolapse, polyp detachment, change of bowel habit and abdominal pain, which can be detected by rectal diagnosis, colonoscopy and abdominal ultrasound. 3, anal fissure: the main symptom is anal pain during defecation and blood in the stool. As the anal fissure opens up when the stool passes, the nerve end in the new trauma surface is stimulated and a small amount of bleeding occurs due to severe pain, and children often do not defecate for fear of pain, which makes the stool dry and difficult to discharge. 4, ulcerative colitis: non-specific chronic inflammatory bowel disease, the lesions are mainly confined to the mucosa of the colon, starting with the rectum, the lesions are inflammation and ulcerative disease, clinical manifestations of bloody diarrhea is the main, can be intermittent episodes, can be accompanied by abdominal pain, urgency, vomiting, anorexia, colonoscopy biopsy can be clear. 5.Irritable bowel syndrome: pre-functional bowel disease characterized by recurrent abdominal pain, diarrhea, constipation or alternating diarrhea and constipation, accompanied by changes in bowel habits and abnormal stool characteristics. 6, eosinophilic colitis: abdominal pain, diarrhea, blood in the stool, often with eczema, urticaria and other parts of the allergic manifestations of the onset of children are often associated with eating, peripheral blood eosinophilia, enteroscopy of mucosal edema, congestion, ulceration, or nodules, mucosal biopsy of a large number of eosinophilic infiltration. 7, Michael’s diverticulum: for the distal ileum diverticulum, is a common digestive tract malformation. The manifestation of dark black blood, large blood volume, and even hemorrhagic shock manifestations, can be complicated by intestinal obstruction, diverticulitis and perforation. Experienced ultrasonographers and small bowel scopes can confirm the diagnosis. 8.Allergic purpura: abdominal pain, blood in the stool, vomiting blood is rare, the lower limbs can be seen typical bleeding spots and spots, often accompanied by joint pain, enteroscopy, gastroscopy can be seen in the intestinal mucosal congestion, edema and vesiculitis and frostbite-like changes. 9, food protein-related rectocolitis: non-IgE-mediated food allergic intestinal diseases, is to rectal, colonic changes as the main features of a class of diseases, clinical toddlers are common, often manifested by diarrhea, blood in the stool, to the bloody stool is common. It occurs mostly in exclusively breastfed children, and is most common in children within 6 months of birth.