When infected, the fistula is red, swollen, painful or abscess dissolved. After inflammation, the fistula will repeatedly become inflamed, fester and fester. The lumen will also develop deeply, and a few infections can extend to the external auditory canal or mastoid process, which is easily misdiagnosed as mastoiditis. People with repeated infections may have local long-term unhealed fistulas or scars, and the patients are very painful. Don't squeeze the secretion in the fistula at ordinary times to avoid infection.