A normal person’s stool should be a yellow, formed banana stool. Depending on the shape or color of the stool, it may be possible to determine the presence of different diseases in the patient. For example, black stools indicate the presence of gastrointestinal bleeding, especially in the upper gastrointestinal tract, which can cause black stools. Some of the most common diseases are erosive bleeding gastritis, gastric ulcer with bleeding or duodenal bulb ulcer with bleeding, gastric cancer with bleeding, etc. If the patient has a bloody stool, there is a high probability that the patient has lower gastrointestinal bleeding. For example, hemorrhoids, anal fissures, ulcers of the colon with bleeding, colon cancer with bleeding, etc. If the patient passes mucopurulent stools, it is likely that the patient has an inflammatory infection of the intestine or Crohn’s disease or ulcerative colitis.