Bloody stool, a lot of blood, very bright. What's going on here?

The main clinical manifestations of gastrointestinal bleeding are acute hemorrhagic anemia and acute peripheral circulatory insufficiency. The color of blood in stool depends on the bleeding site of digestive tract. Upper gastrointestinal bleeding is mostly dark red bloody stool or tar-like black stool. When the lower digestive tract bleeds, it is mostly dark red or bright red bloody stool. However, there are exceptions to both. Acute upper gastrointestinal bleeding, if accompanied by accelerated intestinal peristalsis, can discharge bright red bloody stool instead of black stool. When the small intestine bleeds, if the blood stays in the intestine for a long time, it can be tar-like black stool; When there is a large amount of bleeding in the small intestine and it is discharged quickly, the bloody stool is dark red or even bright red loose stool. When the colon and rectum bleed, because the blood stays in the intestine for a short time, bright red or bright red bloody stool is often discharged. Diseases leading to hematochezia In many anorectal diseases, not only hemorrhoids can lead to hematochezia, but also other anorectal diseases, such as anal fissure, rectal polyp, colon polyp, ulcerative colitis and even rectal cancer. However, the blood in stool caused by each anorectal disease is different in blood color or other symptoms. First, hemorrhoids: bloody stool generally occurs during or after defecation, showing blood drops or jets, bright red blood, and blood is not mixed. Second, anal fissure: the stool caused by anal fissure is bloody, the blood is bright red, there is blood after dripping or wiping with toilet paper, and there is severe pain in the anus after defecation. Third, colorectal polyps: blood is bright red, painless, and blood is not mixed. Fourth, ulcerative colitis: bleeding mixed with mucus or purulent bloody stool, accompanied by abdominal pain, fever, frequent defecation and so on. 5. Rectal cancer: the blood color is bright red or dark red, and it is attached to the surface of the stool in a drop shape; Late purulent stool is often accompanied by anorectal decline, emaciation and changes in stool habits.