Anal swelling and soreness at the tailbone may be caused by hemorrhoids, sinusitis and pelvic inflammatory disease. 1. Hemorrhoids: mainly due to varicose veins around the anus, and will also form a thrombus or venous blood clusters around the anus, thus causing significant anal swelling; due to hemorrhoidal prolapse stimulation resulting in soreness and swelling of the tailbone. 2. Sinusitis: due to the location of the sinuses by the bacterial infection, and then there is a local inflammatory reaction, will occur in the anus of the swelling discomfort, serious can also lead to the formation of abscesses around the anus gap, and then the tailbone soreness. 3. Pelvic inflammatory disease: because the inflammation stimulates the rectum, causing rectal irritation symptoms, resulting in anal distension; with the development of inflammation, may spread to the lumbar muscles, stimulate the lumbar nerves, resulting in caudal soreness. If the patient has anal swelling tailbone soreness, in addition to the above reasons, there may be other factors caused, it is recommended to go to the hospital in a timely manner, differential diagnosis, identify the cause of the disease, and actively cooperate with the doctor for treatment.