Peritonsillar Abscess: Role of CT Imaging
CT neck with IV contrast is NOT routinely necessary for diagnosing peritonsillar abscess, as most cases can be diagnosed clinically based on presentation and physical examination alone. 1, 2
Clinical Diagnosis is Primary
- Peritonsillar abscess is primarily a clinical diagnosis based on characteristic findings: fever, severe throat pain, dysphagia, trismus, "hot potato" voice, and unilateral tonsillar swelling with uvular deviation. 1, 2
- Physical examination revealing these classic features is sufficient to proceed directly to treatment (needle aspiration or incision and drainage) without imaging in straightforward cases. 1, 2
When CT Imaging IS Indicated
Order CT neck with IV contrast in the following specific scenarios:
- Atypical presentations where clinical examination is equivocal or findings don't clearly localize the abscess. 3, 4
- Suspected deep neck space extension beyond the peritonsillar space (parapharyngeal or retropharyngeal involvement), which would alter surgical approach and increase complication risk. 3, 4
- Bilateral peritonsillar abscess (rare presentation requiring high clinical suspicion), where CT facilitates accurate diagnosis and full assessment. 3
- Failed initial drainage or lack of clinical improvement after appropriate treatment, suggesting either incomplete drainage or alternative diagnosis. 4
- Concern for airway compromise or impending complications requiring detailed anatomic assessment before intervention. 1
- Immunocompromised patients where infection may behave atypically or extend more readily. 4
Alternative Imaging: Ultrasound
- Transcutaneous or intraoral ultrasound can differentiate peritonsillar cellulitis from frank abscess and may be particularly useful in pediatric patients to avoid radiation exposure. 5
- Ultrasound can detect the spectrum of peritonsillar infections including uncomplicated tonsillitis, peritonsillar cellulitis, small intratonsillar abscess, and frank peritonsillar abscess. 5
- This modality has limitations in detecting deeper parapharyngeal extension compared to CT. 5
Treatment Approach
The cornerstone of management remains drainage (needle aspiration or incision and drainage) plus antibiotics, regardless of imaging findings. 1, 4, 2
- First-line antibiotics should cover group A streptococcus and oral anaerobes (penicillin, clindamycin, cephalosporins, or metronidazole). 1, 2
- Corticosteroids may reduce symptoms and speed recovery. 1, 4
- Most patients can be managed in the outpatient setting. 1
- Interval tonsillectomy is typically performed 6 weeks after acute infection resolution in recurrent cases. 3
Critical Pitfall to Avoid
Do not delay definitive drainage while waiting for imaging in clinically obvious cases. Ordering CT when clinical examination is adequate delays treatment and exposes patients to unnecessary radiation and cost. 1, 2 The primary therapy is drainage, not imaging—CT should guide approach only when diagnosis is uncertain or complications are suspected.