Rectal bleeding in small amounts is common and usually not life-threatening. It may present as blood in the toilet, on the outside of your stool, or with wiping after a bowel movement. Most common causes are hemorrhoids and anal fissures. However, other more serious causes include colitis (inflammation of the colon), colon polyps, diverticulosis, and cancer.
The term rectal bleeding is usually used to describe bright red blood per rectum which comes from the most distal part of the digestive tract. However, bleeding from the upper digestive tract, small bowel or proximal colon, can produce black, tarry bowel movements (known as melena), dark red bowel movements or bowel movements with blood clots.