Yellow mucus always appears in the anus when urinating, may be anal fistula, rectal prolapse, hemorrhoids and other causes, need to analyze the specific causes. 1. anal fistula: is the anal canal or rectum and the skin connected fistula, the main clinical features of the fistula repeatedly in the mouth of a small amount of pus, mucus secretion, because there is no sphincter restrictions, you can have feces or gas discharged when you urinate. 2. Rectal prolapse: a disease in which the mucosal layer or the whole layer of the rectal wall is displaced downward. When defecation or intra-abdominal pressure increases, a mass may prolapse from the anus, which may be accompanied by the discharge of yellow mucus. 3. hemorrhoids: is the rectal venous plexus abnormal varicose formation of lesions, the most common symptom is pain and bleeding after defecation, but internal hemorrhoids out of the anus can also appear yellow mucus secretion. When the situation of yellow mucus in the anus occurs, it is recommended that the patient should go to the hospital in a timely manner, improve the relevant examination to clarify the cause of the disease, under the guidance of a professional doctor to give reasonable treatment, in accordance with the doctor’s instructions.