40 days after anal fistula surgery blood drops may be normal phenomenon, poor wound healing, constipation, hemorrhoids and other reasons. 1. Normal phenomenon: anal fistula surgery incision is mostly open incision, the patient defecation friction by feces, anal localized tear, there may be a drip-like bleeding, generally bleeding can stop by itself. 2. poor wound healing: 40 days after anal fistula surgery due to poor wound healing, so that the capillaries are exposed, small blood vessels rupture may drip blood. 3. constipation: 40 days after anal fistula surgery patients constipation, discharged feces is relatively dry and defecation strength is relatively large to cause the mucous membrane of the anal opening rupture bleeding. 4. hemorrhoids: 40 days after anal fistula surgery blood may be caused by other diseases of the anus, such as internal hemorrhoids, long-term varicose veins easily lead to hardening of the vein wall, internal hemorrhoids due to friction caused by fecal stimulation and bleeding symptoms. The reason why the blood dripping 40 days after anal fistula surgery is more, it is recommended that patients seek medical attention in time to clarify the cause of the disease, to give reasonable treatment.