What is the cause of blood in the stool in children? The most common cause of blood in the stool in children is anal fissure. Sometimes children with constipation or diarrhea, for example, may cause the anal opening to break down, which is the most common cause of blood in the stool. Of course, there may also be some long-term constipation may lead to hemorrhoids, causing blood in the stool, and some due to abnormalities in the digestive tract, such as bleeding in the gastrointestinal tract, polyps or tumors, gastric ulcers, may cause blood in the stool, which we call blood in the stool. Of course, the more serious is the malignant lesion of intestinal tumor; there is also a part of the congenital malformation is more common, called Meckel’s diverticulum, Meckel’s diverticulum this lesion is very easy to occur blood in the stool, and is called painless bloody stool, it can have a lot of blood, but the stomach does not hurt; also part of the intestinal polyps or tumors; and part of the food because of ingestion, for example, some children may love to eat In this case, the stool is dark brown, similar to blood, and the fecal examination is positive for occult blood, which is often mistaken for blood. There are also cases of colorectitis caused by food allergies or milk protein allergies that lead to blood in the stool. In general, there are many possibilities for bloody stools, and in some rare cases, bleeding from the oral cavity, such as nasal bleeding, can also cause bloody stools when swallowed. Therefore, the overall possibility of bloody stools can also come from the oral cavity, nasal cavity pharynx, and also from the digestive tract lesions. Of course, there may also be lesions at the anal opening that cause bloody stools, so there are many possibilities for blood in the stool. If blood in the stool occurs, it is important to seek timely medical attention, make a clear diagnosis, identify the cause, and provide timely treatment.