To diagnose anal cancer, your doctor will ask about your symptoms, examine you, ask about your medical history and do a rectal examination, which involves inserting a finger inside your anus(wearing a glove and using lubrication).Although a little uncomfortable, this isn't painful. You may be referred to a colorectal surgeon( bowel specialist) who may use a proctoscope or sigmoidoscope to examine the area more carefully. These are narrow tubes with a light that allow your surgeon to examine the lining of your anus and rectum and if necessary, take a biopsy(a small sample of tissue) for testing whether the cells are malignant(cancerous) or benign(not cancerous).If these tests show cancer, further tests will be arranged to see how big the cancer is and whether it has spread.
Attribution: BUPA