Diagnosis begins with a medical history and physical exam. This may be all that is needed to figure out the cause of the discomfort. In other cases, further tests will be needed.
If an STD is suspected, a culture may be done to determine the exact cause of an infection. A culture is a test in which bacteria or other organisms are grown in the lab from a sample of tissue. Tissue is collected by using special cotton swabs to wipe the area around and inside the anus.
If inflammatory bowel disease is suspected, anoscopy or sigmoidoscopy may be advised. These are special procedures that allow a doctor to view the inside of the intestine. They both involve putting a small instrument into the anus that contains a light and a camera.