What are the best diagnostics to check for a peritonsillar abscess?

Best Diagnostic Methods for Peritonsillar Abscess

Clinical examination is usually sufficient for diagnosing peritonsillar abscess, with imaging reserved for atypical presentations, suspected complications, or when the diagnosis is uncertain. 1, 2

Clinical Diagnosis

• Peritonsillar abscess typically presents with fever, sore throat, dysphagia, trismus (limited mouth opening), and a "hot potato" voice 1
• Physical examination revealing unilateral peritonsillar swelling, deviation of the uvula away from the affected side, and fluctuance on palpation is often diagnostic 1
• Clinical impression alone has limited reliability (sensitivity 78%, specificity 50%) and may benefit from confirmatory methods 3
• Needle aspiration remains the gold standard for both diagnosis and treatment of peritonsillar abscess 2

Imaging Modalities

When clinical diagnosis is uncertain or complicated cases are suspected, imaging can be valuable:

Intraoral Ultrasound

• Highest specificity (100%) with good sensitivity (89%) for distinguishing peritonsillar abscess from cellulitis 3
• Advantages include:
  • Non-invasive procedure
  • No radiation exposure
  • Can be performed at bedside
  • Helps guide needle aspiration 4
• May be the preferred first-line imaging when available and when operator expertise exists 3

Computed Tomography (CT)

• High sensitivity (100%) with good specificity (75%) for detecting peritonsillar abscess 3
• Particularly useful for:
  • Suspected extension beyond the peritonsillar space
  • Evaluating potential complications
  • Cases where ultrasound is unavailable or inconclusive 5
• Limitations include radiation exposure and lower spatial resolution compared to MRI 6

Magnetic Resonance Imaging (MRI)

• Superior soft tissue resolution for detailed anatomical assessment 6
• Recommended when complex cases or extension into deep neck spaces is suspected 6
• Limited by availability, longer acquisition time, and higher cost 6

Diagnostic Algorithm

1. Initial Assessment: Clinical examination (inspection, palpation, evaluation for trismus and voice changes) 1
2. First-line Confirmatory Test: Needle aspiration (therapeutic and diagnostic) 2
3. When Imaging is Indicated:
   • Atypical presentation
   • Failed needle aspiration despite strong clinical suspicion
   • Suspected complications or extension
   • Immunocompromised patients 5
4. Imaging Selection:
   • If available and expertise exists: Intraoral ultrasound 3, 4
   • If ultrasound unavailable or inconclusive: CT scan with contrast 3
   • For suspected complex extension or when detailed soft tissue evaluation is needed: MRI 6

Important Considerations

• Diagnostic needle aspiration should not be delayed for imaging in cases with airway compromise or severe symptoms 5
• Antibiotic therapy should be initiated promptly, covering both aerobic and anaerobic bacteria 2
• Consider adjunctive corticosteroids to reduce symptoms and speed recovery 4, 5
• Complications to watch for include airway obstruction, aspiration, or extension of infection into deep neck tissues 1