How do you differentiate peritonsillar abscess from tonsillitis?

Differentiating Peritonsillar Abscess from Tonsillitis

The key diagnostic features that differentiate peritonsillar abscess from tonsillitis include unilateral peritonsillar swelling, uvular deviation, trismus, muffled "hot potato" voice, and severe asymmetric throat pain, which are not typically present in uncomplicated tonsillitis.

Clinical Presentation Differences

Peritonsillar Abscess

• Unilateral presentation (bilateral is rare, occurring in only 4.9% of cases) 1
• Severe, asymmetric throat pain with referred pain to the ear on the affected side
• Trismus (limited mouth opening) due to inflammation of pterygoid muscles
• Muffled "hot potato" voice due to soft palate edema
• Uvular deviation away from the affected side
• Peritonsillar swelling with displacement of the tonsil medially and inferiorly
• Drooling may be present due to painful swallowing
• Systemic symptoms including fever, rigors, and malaise
• Neck tenderness or swelling may indicate spread of infection

Tonsillitis

• Bilateral tonsillar inflammation (typically symmetric)
• Tonsillar exudates visible on both tonsils
• Sore throat without significant asymmetry
• Absence of trismus or with minimal limitation
• Normal uvula position (no deviation)
• No peritonsillar swelling
• Systemic symptoms including fever, headache, and malaise

Physical Examination Findings

When examining a patient with suspected peritonsillar abscess, focus on:

1. Oropharyngeal inspection:

   • Look for asymmetric peritonsillar swelling (usually superior pole)
   • Observe for uvular deviation away from affected side
   • Note any tonsillar exudates

2. Assessment of trismus:

   • Measure mouth opening (limited in peritonsillar abscess)
   • Evaluate pain with jaw movement

3. Neck examination:

   • Check for tender cervical lymphadenopathy
   • Assess for neck swelling or tenderness suggesting spread of infection

4. Voice quality:

   • Listen for muffled "hot potato" voice characteristic of peritonsillar abscess

Diagnostic Approach

When clinical diagnosis is uncertain, especially with severe trismus limiting examination:

1. Ultrasonography:

   • Can verify presence of abscess in approximately 90% of cases 2
   • Particularly useful when clinical examination is limited due to trismus or lack of patient cooperation

2. Needle aspiration:

   • Both diagnostic and therapeutic
   • Confirms presence of purulent material
   • Should be performed at the point of maximum swelling

Warning Signs for Complications

Be vigilant for signs of potentially life-threatening complications:

• Respiratory distress suggesting airway compromise
• Neck swelling indicating possible spread to deep neck spaces
• Severe trismus limiting oral intake
• Atypical presentation in older patients without history of recurrent tonsillitis (may suggest underlying malignancy) 3

Management Considerations

The management differs significantly:

• Peritonsillar abscess: Requires drainage (needle aspiration, incision and drainage, or immediate tonsillectomy) plus antibiotics 2
• Tonsillitis: Typically managed with antibiotics alone if bacterial in origin

Clinical Pitfalls to Avoid

1. Missing bilateral peritonsillar abscesses: Though rare, bilateral abscesses can occur and may lead to catastrophic airway compromise if not identified 1, 4

2. Overlooking underlying malignancy: Peritonsillar abscess in older patients without history of recurrent tonsillitis should raise suspicion for possible underlying malignancy, particularly squamous cell carcinoma or lymphoma 3

3. Failing to recognize extension: Peritonsillar abscesses can extend to retropharyngeal spaces and even the mediastinum in severe cases 5

4. Misdiagnosing phlegmonous peritonsillitis: This condition may present similarly to peritonsillar abscess but requires only antibiotics rather than drainage 2

By carefully evaluating these distinguishing features, clinicians can accurately differentiate between peritonsillar abscess and tonsillitis, ensuring appropriate and timely management to prevent serious complications.