Internal hemorrhoids: Covered by mucous membrane, located above the dentate line, formed by the internal venous plexus, commonly found in the left median, right anterior and right posterior 3, often with a history of blood in the stool and prolapse. External hemorrhoids: Surface covered by skin, located below the tooth line, formed by the external venous plexus, commonly thrombosed external hemorrhoids, connective tissue external hemorrhoids (skin pendulous), varicose veins external hemorrhoids and inflammatory external hemorrhoids. Mixed hemorrhoids: near the dentate line, covered by skin mucosal junction tissue, formed by anastomosing veins between the internal and external hemorrhoidal plexus that are connected to each other have both internal and external characteristics. Internal hemorrhoids stage Internal hemorrhoids four stages According to the 2000 Chinese Medical Association Surgical Group “Provisional Standards for the Diagnosis and Treatment of Hemorrhoids”, internal hemorrhoids are often clinically classified into four stages depending on the pathological changes and the degree of development. Stage Ⅰ, painless, mainly with bleeding, discharge and itching. Stage II, with blood in the stool Hemorrhoids, hemorrhoids prolapse with defecation, but can be returned on their own. Stage III (also called late stage), internal hemorrhoid prolapses outside the anal opening, or prolapses outside the anal opening with each bowel movement, and cannot be returned by itself, and must be held back by hand. In stage IV, the internal hemorrhoid prolapses out of the anal opening and cannot be returned to the inside of the anus. This is the most serious condition of internal hemorrhoids.