Hemorrhoids are divided into internal, external and mixed hemorrhoids. The main clinical symptoms of internal hemorrhoids are bleeding and prolapse. The formation of internal hemorrhoids (and external hemorrhoids as well) are caused by bruising of the buttocks. Internal hemorrhoids are composed of enlarged varicose vein plexuses under the mucous membrane above the dentate line of the anus, forming soft venous masses. As the nerves on the dentate line are vegetative. It is not sensitive to painful stimuli. Therefore, the pain of patients with internal hemorrhoids is usually not obvious.