Abses Peritonsilar (Quinsy)

01Pathophysiology

Peritonsillar abscess develops as a complication of acute tonsillitis or pharyngitis that extends beyond the tonsillar capsule into the peritonsillar space, a potential space located between the tonsillar capsule and the superior pharyngeal constrictor muscle. The infection begins as a cellulitis (peritonsillar cellulitis or "phlegmon") and, if untreated, organizes into a walled-off collection of pus.

The most commonly implicated organism is Group A beta-hemolytic Streptococcus (GAS), but cultures frequently reveal polymicrobial flora, including anaerobes such as Fusobacterium necrophorum and Prevotella species. This polymicrobial nature is why broad-spectrum coverage is required for treatment.

The abscess typically forms at the superior pole of the tonsil, between the anterior and posterior tonsillar pillars. As the abscess expands, it pushes the tonsil medially and inferiorly, which causes the classic finding of contralateral uvular deviation. The inflammatory swelling involves the medial pterygoid muscle, which explains the hallmark sign of trismus (inability to fully open the mouth). This anatomic relationship is a tested concept: trismus is not caused by pain alone but by direct inflammatory involvement of the pterygoid musculature.

The patient develops a "hot potato" voice because the enlarged peritonsillar mass displaces the soft palate and narrows the oropharyngeal airway, altering resonance. Drooling occurs because the severe odynophagia prevents the patient from swallowing their own saliva. Referred otalgia is explained by shared sensory innervation via the glossopharyngeal nerve (CN IX), which supplies both the tonsillar region and the middle ear.

The feared complication is extension into the parapharyngeal or retropharyngeal space, which can lead to airway compromise, mediastinitis, or erosion into the carotid sheath (causing internal jugular vein thrombophlebitis, known as Lemierre syndrome, classically associated with Fusobacterium necrophorum).

02Classification and Clinical Manifestation

Clinical Manifestation

03Diagnostic Workup

Peritonsillar abscess is primarily a clinical diagnosis. In a patient presenting with unilateral tonsillar bulging, uvular deviation, trismus, and a "hot potato" voice, the diagnosis is clear from examination alone. Needle aspiration serves a dual role: it confirms the presence of pus (distinguishing a true abscess from cellulitis) and provides initial drainage.

When the clinical picture is ambiguous, particularly when trismus limits adequate oral examination, CT of the neck with IV contrast is the imaging study of choice. It demonstrates a rim-enhancing hypodense collection in the peritonsillar space and is critical for evaluating whether the infection has spread into the parapharyngeal or retropharyngeal spaces.

Intraoral ultrasound has gained favor as a bedside tool in the emergency department because it can rapidly distinguish a drainable abscess from cellulitis without radiation. However, CT remains superior for assessing deep space involvement.

Routine laboratory studies (CBC, CRP) may show leukocytosis and elevated inflammatory markers but are noncontributory to the diagnosis. They are useful primarily for monitoring the septic or immunocompromised patient.

04Management and Treatment

Acute stabilization begins with airway assessment. Although frank obstruction is uncommon, the possibility of airway compromise should be evaluated in every patient, particularly those with bilateral involvement, extensive swelling, or deep space extension.

The next best step after clinical diagnosis is needle aspiration. This is both diagnostic and therapeutic. The aspiration is performed at the superior pole of the tonsil (the most common abscess location), using an 18-gauge needle with a guard to limit depth of penetration and avoid injury to the internal carotid artery, which courses posterolateral to the tonsillar fossa. Aspiration of pus confirms the diagnosis and often provides immediate symptomatic relief.

If needle aspiration fails to yield pus or if symptoms recur after drainage, formal incision and drainage is the next step. Some practitioners proceed directly to I&D as the primary intervention.

Antibiotic therapy should provide coverage for GAS, oral anaerobes, and staphylococci. The first-line regimen is ampicillin-sulbactam 3 g IV every 6 hours. For penicillin allergy, clindamycin is the standard alternative and offers good anaerobic and gram-positive coverage. Once the patient can tolerate oral intake, antibiotics are transitioned to amoxicillin-clavulanate or oral clindamycin to complete a 14-day total course.

A single dose of IV dexamethasone is supported by evidence showing faster symptom resolution, reduced pain, and improved ability to resume oral intake. This is a commonly tested adjunct.

Interval tonsillectomy is recommended for patients with recurrent peritonsillar abscess (two or more episodes). Immediate (or "hot") tonsillectomy during the acute infection is less commonly performed but may be appropriate in select cases where drainage fails.

Contraindications and cautions: In patients with suspected extension into the parapharyngeal space or signs of Lemierre syndrome (spiking fevers, rigors, neck tenderness along the sternocleidomastoid, pulmonary infiltrates), CT imaging is mandatory and surgical consultation for operative drainage should not be delayed. Anticoagulation may be considered for Lemierre syndrome in addition to prolonged IV antibiotics.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students lose points on peritonsillar abscess questions is by confusing it with simple tonsillitis and selecting "antibiotics alone" as the answer. The test-writer includes trismus, uvular deviation, or a "hot potato" voice precisely to signal that the infection has progressed beyond the tonsil. When any of these findings are present, drainage is required in addition to antibiotics; antibiotics alone are insufficient.

A second trap involves differentiating peritonsillar abscess from retropharyngeal abscess. Both can present with drooling and a muffled voice. The key: retropharyngeal abscess occurs in young children and features neck rigidity with refusal to extend, whereas peritonsillar abscess occurs in young adults and features trismus with uvular deviation.

Students also sometimes confuse the voice change in quinsy with that of epiglottitis. In peritonsillar abscess, the voice is muffled ("hot potato") due to oropharyngeal narrowing, whereas epiglottitis produces stridor and a "toxic" appearance with rapid deterioration. The presence of unilateral pharyngeal bulging is the discriminating finding.

Finally, be aware of the Lemierre syndrome association. If a vignette describes a young patient with a recent sore throat followed by spiking fevers, rigors, and septic pulmonary emboli (multiple peripheral lung nodules on chest imaging), think Fusobacterium necrophorum and internal jugular vein thrombophlebitis. This is the feared complication of untreated or inadequately treated peritonsillar or pharyngeal infections.

The core competency being tested is the ability to recognize the clinical constellation that distinguishes a drainable abscess from uncomplicated pharyngitis and to understand that the next best step is drainage, not just escalation of antibiotics.