Can stomach ulcers cause blood in the stool?

Gastric ulcers can potentially cause rectal bleeding in severe cases.

When an ulcer erodes into a blood vessel, it may lead to gastrointestinal bleeding, with blood mixing into the stool. This often presents as black, tarry stools, known as melena, due to the reaction of blood to gastric acid and digestive enzymes during its passage through the digestive tract. If the amount of bleeding is large or the bleeding rate is fast, bright red blood in the stool may also occur. In addition, when gastric ulcers are in the active phase, the inflammatory response of the gastric mucosa intensifies, which may lead to the formation of new bleeding sites and similarly cause rectal bleeding.

However, not all gastric ulcers result in rectal bleeding. The occurrence of bleeding from a gastric ulcer is related to the severity of the condition. If the ulcer is not particularly severe and has not caused gastrointestinal bleeding or perforation, rectal bleeding may not occur. Rectal bleeding can also be a symptom of various other conditions, such as hemorrhoids, anal fissures, inflammatory bowel disease, colonic polyps, or cancer. Therefore, if blood appears in the stool, prompt medical attention is necessary.