Anal fistula wound healing and then break open without bleeding is generally caused by poor wound healing, pseudo healing, defecation difficulties and other reasons. 1. poor wound healing: poor wound healing generally refers to the wound in the healing process of the wound is infected, nutritional intake is insufficient to recover slowly and other factors, resulting in the wound is not healed, will break open without causing bleeding. 2. False healing: false healing refers to the surface of the wound seems to have healed, but the deeper layers are not healed, the deeper layers of the fluid, infection, cavity, etc., by the external force or pulling the wound to break open without bleeding. 3. Difficulty in defecation: The dryness of the stool can cause difficulty in defecation, which can usually cause the anal fistula surgical wound to tear, resulting in pain, swelling and other phenomena of the wound. It is recommended that patients go to the hospital for examination in time after the wound is broken open, to clarify the cause of the disease, and give treatment as soon as possible under the guidance of the doctor.