How can I determine if a patient has quinsy (peritonsillar abscess)?

Diagnosing Quinsy (Peritonsillar Abscess)

Diagnose quinsy based on the classic triad of severe unilateral throat pain, trismus, and "hot potato" voice, combined with physical exam findings of unilateral tonsillar swelling with uvular deviation away from the affected side; when clinical findings are equivocal, use point-of-care intraoral ultrasound to confirm the presence of an abscess cavity before attempting drainage.

Clinical Presentation

The diagnosis of quinsy relies primarily on recognizing the characteristic clinical features:

Key Symptoms

• Severe unilateral throat pain that typically worsens over 3-5 days
• Trismus (difficulty opening the mouth due to pterygoid muscle spasm)
• "Hot potato" or muffled voice (speaking as if holding a hot object in the mouth)
• Odynophagia (painful swallowing) often with drooling
• Fever (commonly 38-39°C)

Physical Examination Findings

• Unilateral tonsillar swelling with bulging of the peritonsillar area
• Uvular deviation away from the affected side (toward the unaffected side)
• Erythema and edema of the soft palate
• Ipsilateral tender cervical lymphadenopathy (especially submandibular nodes)

Diagnostic Challenges

Clinical examination alone is unreliable, with sensitivity of only 78% and specificity of 50% 1. The critical challenge is distinguishing peritonsillar abscess from peritonsillar cellulitis, as this distinction fundamentally changes management—cellulitis requires antibiotics alone, while abscess requires drainage.

Role of Imaging

Point-of-Care Ultrasound (Preferred)

Intraoral ultrasound is the most practical and accurate diagnostic tool when clinical findings are uncertain 2, 1:

• Sensitivity: 89-100%
• Specificity: 75-100% 1
• Advantages: No radiation, rapid, bedside availability, can guide needle aspiration, cheaper than CT
• Key finding: Low echogenic (hypoechoic) area representing the abscess cavity 3

Practical considerations:

• External (transcervical) ultrasound is easier to perform and well-tolerated but less precise for determining puncture site 4
• Intraoral ultrasound provides better localization for drainage but requires a small transducer and cannot be performed with severe trismus 4
• Emergency physician-performed intraoral ultrasound reliably diagnoses PTA and improves aspiration success 2

CT Imaging

Contrast-enhanced CT (CECT) is highly accurate (sensitivity 100%, specificity 75%) 1 but should be reserved for:

• Suspected complications (parapharyngeal or retropharyngeal extension)
• Failed drainage attempts
• Concern for alternative diagnoses (tumor, vascular abnormality)
• When ultrasound is unavailable or inconclusive 3

Plain CT is insufficient for distinguishing abscess from cellulitis and should not be relied upon alone 3.

Diagnostic Algorithm

1. Assess for classic clinical triad: severe unilateral throat pain + trismus + muffled voice
2. Examine for physical findings: unilateral tonsillar bulging with contralateral uvular deviation
3. If diagnosis is clinically obvious: proceed directly to drainage
4. If diagnosis is uncertain: perform point-of-care intraoral ultrasound to confirm abscess cavity
5. If ultrasound unavailable or equivocal AND high clinical suspicion: consider CECT or diagnostic needle aspiration
6. If imaging shows only cellulitis: treat with antibiotics alone, no drainage needed

Common Pitfalls

• Don't rely on clinical impression alone—it misses abscesses in 22% of cases and incorrectly diagnoses abscess when only cellulitis is present in 50% of cases 1
• Don't perform blind needle aspiration without imaging confirmation in equivocal cases—this risks unnecessary procedures and vascular injury 4
• Don't order plain CT—it provides insufficient information to distinguish abscess from cellulitis 3
• Don't forget to assess for complications—examine for neck swelling, respiratory distress, or signs of deep neck space involvement that would require CECT