Blood in the stool

A small amount of bright red blood on the surface of the stool is usually caused by irritation of the rectum or a small tear in the opening at the end of the rectum (anus). A moderately large amount of blood in the stool often means there is bleeding in the digestive (gastrointestinal) tract between the esophagus and the rectum, caused by inflammation, irritation, infection, or structural problems of the digestive tract.

Irritation may occur after several loose bowel movements. It is not serious if there is only a small amount of blood and the bleeding stops after the bowel looseness is controlled. Passing a hard stool can also cause a tear in the anus or irritate hemorrhoids, causing a small amount of bleeding that stops in a short time.

Bloody stools may occur as one large, bloody bowel movement or several bowel movements containing a moderate amount of blood (enough to turn the water in the toilet bowl red). Depending upon where the blood is coming from and how quickly it is moving through the digestive system, the blood may be bright red, reddish brown, or black and tarry. If the site of the bleeding is above the rectum, the blood will be mixed in with the stool.