If the swelling is far from the anus, it is not considered to be related to the anus and may be a boil or perianal purulent sweat gland infection, which is easier to treat and can usually be cured without surgery. If it is close to the anus (generally the swollen area is within 5cm from the anus), it is highly suspected that it may be a perianal abscess caused by sinus infection and needs to be treated with surgery at the earliest possible time to avoid the infection foci going to the perianal space, which will aggravate the disease and increase the difficulty of surgery, and the postoperative trauma is also large and painful. The diagnosis can be confirmed with a look at the anus and an anal finger examination.