The skin and subcutaneous tissues of the anal verge bear the brunt of surgery for anal diseases, in which the nerves and blood vessels are also damaged at the same time. Damaged tissue cells release various inflammatory mediators that stimulate the peripheral nerves, so the wound will experience pain and bleeding. After surgery, all kinds of tissues have to accelerate the growth to repair the damaged part, but their growth rate is very different, connective tissue grows the fastest, followed by epithelial tissue, nerve tissue repair is the slowest. Wound growth to the late stage, the newborn nerve endings only began to repair, the development is not yet fully mature, very sensitive, the slightest stimulation will produce impulses, and the formation of the message is not yet complete or unclear, resulting in the production of itchy sensation. When the wound is completely healed, the newborn nerve endings will gradually develop and perfect, it is possible to adapt to the new environment, the itch will disappear naturally.