Peritonsillar Abscess
The most likely diagnosis is peritonsillar abscess (PTA), given the classic triad of severe unilateral sore throat with trismus, muffled voice, and inability to visualize the posterior oropharynx due to marked trismus. 1, 2
Key Clinical Features Supporting This Diagnosis
The patient presents with the hallmark features of PTA:
- Severe unilateral (right-sided) sore throat with odynophagia - the gradually worsening pain localized to one side is characteristic 3, 4
- Marked trismus - this space-occupying lesion in the oral cavity causes significant jaw restriction, preventing adequate visualization of the posterior pharynx 1, 2
- Muffled voice (often described as "hot potato voice") - reflects the mass effect in the peritonsillar space 2, 3
- Ipsilateral ear pain - referred pain from the tonsillar region is common 4
- Drooling - indicates difficulty managing secretions due to severe odynophagia 2, 3
- Fever (39.1°C) and tachycardia - systemic signs of infection 1
Why Other Diagnoses Are Less Likely
Epiglottitis typically presents with stridor, respiratory distress, and a toxic appearance with the patient preferring to sit upright and lean forward. This patient has no stridor, normal pulse oximetry (99%), and can maintain her airway, making epiglottitis unlikely 5
Retropharyngeal abscess would present with neck stiffness, difficulty extending the neck, and visible posterior pharyngeal wall swelling. The normal neck exam argues against this diagnosis 2
Eustachian tube dysfunction does not cause fever, trismus, muffled voice, or severe sore throat - it presents with ear fullness and hearing changes without systemic symptoms 5
Critical Diagnostic Pitfall
The inability to visualize the posterior oropharynx due to trismus should not delay diagnosis. The clinical presentation alone is sufficient to warrant urgent intervention. Attempting forced examination risks precipitating airway compromise 2, 3
Immediate Management Priority
Airway assessment is the first priority, as PTA carries risk of impending airway obstruction, though this patient currently shows no respiratory compromise with normal oxygen saturation and no stridor 2, 4
Definitive diagnosis requires needle aspiration or incision and drainage of the peritonsillar space, which will yield purulent material (commonly Streptococcus pyogenes) and provide both diagnostic confirmation and therapeutic benefit 2, 3, 4
Important Clinical Caveat
While unilateral presentation is classic, the absence of visible uvular deviation or asymmetric tonsillar swelling due to trismus does not exclude PTA. Some cases present as "occult" peritonsillar abscess without the typical asymmetric findings 6
Answer: C. Peritonsillar abscess