Symptoms that indicate blood in the stool are finding blood in the stool itself or on toilet paper or passing stool that is tarry and black, explains WebMD. Other signs and symptoms are pain in the abdomen, diarrhea, vomiting, heart palpitations and fainting.
A person who is passing blood in his stool may also suffer unexplained weight loss and difficulty in breathing, according to WebMD. The severity of the symptoms depends on how much blood is being lost and the location in the body of the bleeding. Causes of blood in the stool range from cancer to peptic ulcers to diverticular disease and anal fissures.
A doctor finds the cause of the bleeding so he can use the appropriate treatment to stop it, says WebMD. He might perform a laparotomy, where he makes an incision in the abdomen and looks for signs of bleeding. He orders lab tests to see if the patient is anemic, has clotting problems or has an infection of the H. pylori bacteria. The doctor also uses angiography. In this procedure, a dye is injected into the patient's vein. The dye allows the physician to see the blood vessels on an X-ray or CT scan and to pinpoint the location of the bleed. This is because the dye also passes out of a damaged blood vessel.