To diagnose an anal fissure, your doctor will ask about your symptoms and medical history and may examine the area by gently parting the buttocks. If your doctor can see the fissure, s/he will usually prescribe treatment. If the tear isn't visible, it's important to make the correct diagnosis as other conditions can cause similar symptoms. Your doctor may refer you to a colorectal surgeon(a doctor who specialises in conditions that affect the bowel).At the hospital, a detailed examination can be done under anaesthesia to help reduce discomfort.
Attribution: BUPA