Exams and Tests

Peritonsillar abscess is usually diagnosed based on history and physical examination. A peritonsillar abscess is easy to diagnose when it is large enough to see. The doctor will look into your mouth using a light and, possibly, a tongue depressor. Swelling and redness on one side of the throat near the tonsil suggests an abscess. The doctor may also gently push on the area with a gloved finger to see if there is pus from infection inside.

• Lab tests and x-rays are not used often. Sometimes an x-ray or an ultrasound will be performed, typically to make sure other upper airway illnesses are not present. These conditions may include the following:
  
  
  • Epiglottitis, an inflammation of the epiglottis (the flap of tissue that prevents food from entering the windpipe)
    
    
  • Retropharyngeal abscess, a pocket of pus that forms beneath the soft tissue in the back of the throat (like a peritonsillar abscess but in a different location)
    
    
  • Peritonsillar cellulitis, an infection of the soft tissue itself (a peritonsillar abscess forms beneath the surface of the tissue)

• Your doctor may test you for mononucleosis, a virus. Some experts suggest that mono is associated with up to 20% of peritonsillar abscesses.

• Your doctor also may send some of the pus from the abscess to the lab so the exact bacteria can be identified. Even so, identifying the bacteria rarely changes treatment.