If a bag grows at the anal opening, do not be nervous, you should analyze the cause. The first is that it could be a hemorrhoid, which is a relatively common condition, mostly formed when the nucleus of the hemorrhoid prolapses from the anus during increased abdominal pressure and heavy alcohol consumption. If the hemorrhoid is hard and painful, it may be a thrombosed external hemorrhoid, which requires surgical treatment, i.e. thrombectomy. If it is a mixed hemorrhoid with edema and necrosis, it can also cause pain and should also be treated surgically. The second is a possible perianal abscess, which may be caused by an infection of the anal sinus due to diarrhea, etc., and spread to the perianal skin. This kind of need to do perianal ultrasound, if clear is perianal abscess, should perform perianal abscess incision and drainage.