Blood when wiping the buttocks is often due to the following reasons: 1. Hemorrhoids: When the patient has internal hemorrhoids, there will be bleeding after defecation, in the form of drops and without obvious pain, which can be clarified by going to the hospital’s general surgery or anorectal surgery. If it is the disease, you need to actively adjust your diet and treat it with medication sitz bath. For example, try not to drink alcohol, do not eat spicy food, appropriate intake of fresh fruits and vegetables, sitz bath solution can choose diluted warm potassium permanganate water or Chinese medicine preparations. If conservative treatment does not work, surgery is required. 2. anal fissure: bleeding during defecation and severe pain, you can go to the hospital for clarification. 3. swelling: there may be benign polyps or even malignant tumors caused by the growth of the anus and rectum, you can check the rectoscopy or colonoscopy for clarification.