Blood in the stool is bright red, indicating that the bleeding is in the rectum or anus, common causes are hemorrhoids, anal fissure, rectal polyps and other causes. 1. hemorrhoids: patients who suffer from hemorrhoids, the pressure in the blood vessels may increase during defecation, thus rubbing the bulging varicose veins and veins, resulting in venous rupture, the symptoms of blood in the stool bright red. Mostly seen in internal hemorrhoids, mixed hemorrhoids. 2. Anal fissure: if the patient suffers from anal fissure, there may be fissure at the anus, and the symptoms of anal fissure often manifest as bleeding from the fissure, pain, etc., so the patient may lead to blood in the stool with a bright red color when defecating. 3. Rectal polyps or rectal cancer: if the patient suffers from rectal polyps, the mucous membrane on the surface of rectal polyps may be torn during defecation, resulting in bleeding; the mucous membrane on the surface of rectal cancer is prone to erosion and bleeding. So patients may have the symptom of blood bright red in stool. In addition, anal trauma, coagulation dysfunction patients with constipation may also appear stool with bright red blood. It is recommended that patients should go to the hospital to find out the cause of blood in the stool, and then do the relevant treatment.