Diagnostic Testing for Peritonsillar Abscess
Clinical examination should be the first-line diagnostic approach for peritonsillar abscess, with CT with intravenous contrast reserved for cases where the diagnosis remains uncertain or complications are suspected. 1
Initial Diagnostic Approach
- Clinical examination including digital palpation is essential and sufficient for most cases, as peritonsillar abscess can typically be diagnosed based on physical findings alone 1
- Imaging should be reserved specifically for atypical presentations, unclear diagnoses, or when complications are suspected 1
- The traditional reliance on imaging may actually lead to worse outcomes, including increased ED return visits and recurrent abscess formation 2
When Imaging Is Indicated
If clinical examination is inconclusive or complications are suspected, CT with intravenous contrast is the preferred imaging modality for the following reasons:
- CT with IV contrast helps visualize and characterize fluid collections and demonstrates rim-enhancement of abscesses, which is critical for accurate diagnosis 1
- CT is less operator-dependent than ultrasound and maintains accuracy even when significant pain limits physical examination 1
- Non-contrast CT has lower sensitivity for detecting abscess formation and is not recommended 1
Alternative Imaging Modalities
Ultrasound
- Ultrasound (both transcutaneous and intraoral approaches) can be used as a diagnostic tool, particularly in pediatric populations where radiation exposure is a concern 3, 4
- However, ultrasound is more operator-dependent and has limited utility as an initial imaging modality for suspected soft tissue infections in this region 1
- Intraoral ultrasound has been described as helpful but requires specific technical expertise 4
MRI
- MRI offers superior soft tissue resolution but is not typically used as initial imaging due to limited availability in emergency settings and longer acquisition times 1
- MRI would be more appropriate for complex cases, recurrent disease, or when detailed anatomical information is needed 1
Important Clinical Pitfalls
- Obtaining CT scans when clinical diagnosis is adequate may paradoxically lead to worse outcomes, including increased odds of recurrent PTA (OR 1.943), return ED visits (OR 5.900), and unnecessary prescriptions 2
- The increased use of antibiotics, opioids, and steroids in CT-imaged patients suggests potential overtreatment 2
- Needle aspiration remains the gold standard for both diagnosis and treatment once peritonsillar abscess is suspected 5