There are many reasons for long-term bleeding in the stool. When blood in the stool occurs, observe the color as well as the amount of blood in the stool. A brighter color indicates that the bleeding site is closer to the anus, while a darker color of blood in the stool indicates that the bleeding site is farther from the anus, which may be upper gastrointestinal bleeding. Black colored stool may also be upper gastrointestinal bleeding, such as gastric ulcer, small intestine polyp, small intestine diverticulum, or even esophageal colon tumor, which may also cause blood in stool. Brighter colored blood in the stool may be internal hemorrhoid bleeding, which occurs when bowel habits change or abdominal pressure increases, and bleeding stops after a bowel movement. It may also be a rectal polyp or rectal adenoma, which can cause blood in the stool due to rupture of blood vessels in the rectal mucosa. If you have long-term bleeding in the stool, you should perform gastroscopy, colonoscopy and, if necessary, small intestine capsule endoscopy to clarify the cause and location of the bleeding.