How doctor exam the cause of blood in stool?

Various: A rectal exam (gloved finger in the rectum) can sometimes provide the answer, particularly if the problem is a hemorrhoid. Depending on age, health problems, symptoms, and type of bleeding, further tests may need to be done including possibly colonoscopy (under sedation, a fiberoptic camera is inserted into the rectum and is threaded through the colon to look directly for the cause of bleeding).