Hematochezia is most characteristic of which type of diarrhea?

• A. Small bowel
• B. Large bowel
• C. Both
• D. Neither

Answer: (B)

Bleeding appearance can localize the source of the problem. Hematochezia—fresh blood with stool—usually comes from the lower GI tract, specifically the colon or rectum. When diarrhea involves the large bowel, bleeding is more likely to be seen as bright red blood per rectum because the blood is close to the exit and is less digested. In contrast, bleeding from the small bowel tends to produce melena (dark, tarry stools) as blood is digested during its long passage, or occult blood without obvious bright blood. So hematochezia is most characteristic of large bowel diarrhea.