The most common cause may be caused by hemorrhoids. This type of blood in the stool often occurs during or after defecation and is bright red, does not mix with stool, and comes down in drips or jets; the bleeding shows a certain periodicity. Blood in the stool caused by anal fissures is also more common, with bright red blood, and unlike hemorrhoids, it is often painful and severe in the anus after defecation. Sometimes intestinal tumors (rectal cancer) can also cause blood in the stool, most similar to hemorrhoid bleeding, mostly in the blood or mixed with mucus and dark blood clots in the stool, and accompanied by bad odor, persistent, in the late stage accompanied by anorectal cramps and generalized wasting, the frequency of stool increases, there is constipation and diarrhea alternately. The blood is bright red, painless, and does not mix with stool, and some patients have grooves on the surface of the stool. Based on the characteristics and symptoms of blood in stool, it is still difficult to make accurate self-judgment. It is best to go to a specialized hospital for examination as soon as possible, usually through anal finger diagnosis and colonoscopy can make accurate diagnosis and facilitate early treatment to avoid inducing other diseases.