Hemorrhoids are clumps or cushions of blood vessels and supporting tissue that form part of the normal anatomy of the rectum. Hemorrhoidal disease occurs when pressure increases within the vessels, causing these cushions to enlarge, become painful, and sometimes bleed upon defecation. This condition affects approximately 5% of the general population, with up to 50% of people over the age of 50 years having symptoms at some time. Internal hemorrhoids lie within the anal canal, and are classified as grade I (bleeding), II (hemorrhoids that protrude or prolapse outside the anus upon defecation, but withdraw spontaneously), III (hemorrhoids that protrude and then must be pushed back inside), and IV (hemorrhoids that are permanently protruded). Grades III and IV hemorrhoids usually require surgery, but grades I and II hemorrhoids can be treated by a variety of office procedures including rubber band ligation. Other procedures that are used to treat grades I and II hemorrhoids include sclerotherapy, bipolar diathermy, and infrared coagulation, also known as photocoagulation.