What Could Cause Blood in a Bowel Movement?

Causes of blood in a bowel movement include hemorrhoids, an anal fissure, an anal abscess, diverticulitis and inflammatory bowel disease, according to Cleveland Clinic. The color of the blood helps determine where the blood is coming from, helping to diagnose the condition. For example, bright red blood means that the blood is coming from the rectum or the lower part of the colon and is typically due to hemorrhoids.