Peritonsillar Abscess (Quinsy)

Peritonsillar abscess (PTA), classically called Quinsy, is a collection of pus in the loose areolar peritonsillar space between the fibrous capsule of the palatine tonsil and the superior constrictor muscle. It is the commonest deep neck space infection and a high-yield ENT topic where the examiner loves to test localising signs, the drainage debate, and differentiation from parapharyngeal and retropharyngeal abscess.

Definition & relevant anatomy

The peritonsillar (paratonsillar) space is a potential space lying between:

• Medially – the fibrous capsule of the palatine tonsil
• Laterally – the superior constrictor muscle of the pharynx
• It contains loose areolar tissue, hence pus collects easily here.

The abscess most commonly forms at the upper pole of the tonsil (supratonsillar space) because the loose tissue is most abundant superiorly. This is the classic site, producing the characteristic bulge above and lateral to the tonsil.

High-yield: PTA is a collection between the tonsillar capsule and superior constrictor muscle. The commonest site is the upper/superior pole of the tonsil.

The Weber glands — mucous salivary glands in the supratonsillar space that drain through ducts to the tonsillar surface — are implicated in pathogenesis. Obstruction of these glands during acute tonsillitis is thought to be a key initiating factor, which also explains why PTA can occur even in patients who have had tonsillectomy (residual Weber gland tissue).

Etiology & pathophysiology

PTA is usually a complication of acute follicular tonsillitis that spreads beyond the tonsillar capsule. The natural progression is:

Acute tonsillitis → peritonsillitis (cellulitis of peritonsillar space) → peritonsillar abscess (frank pus collection)

A minority arise de novo from infected/obstructed Weber glands without preceding clinically obvious tonsillitis.

Causative organisms

The infection is typically polymicrobial (mixed aerobic and anaerobic flora):

Category	Key organisms
Aerobes	Streptococcus pyogenes (Group A beta-haemolytic strep — most common single aerobe), Staph aureus, Haemophilus influenzae
Anaerobes	Fusobacterium necrophorum, Prevotella, Peptostreptococcus, Bacteroides

High-yield: The most common single organism is Group A beta-haemolytic Streptococcus (S. pyogenes), but the abscess is usually polymicrobial with prominent anaerobes (Fusobacterium). Hence antibiotic cover must include anaerobic coverage.

Epidemiology

• Typically affects young adults / adolescents (20–40 years) — older than the peak age for tonsillitis.
• Usually unilateral; bilateral PTA is rare and easily missed.
• Smoking is a recognised risk factor.

Clinical features

The patient is usually toxic, febrile, dehydrated, and in obvious distress, with a 3–5 day history of worsening sore throat after a tonsillitis episode that seemed to improve then deteriorated, with pain becoming severe and strictly unilateral.

The classic constellation (very examinable):

Sign / Symptom	Mechanism
Severe unilateral throat pain with referred otalgia (same side)	Glossopharyngeal nerve (CN IX) referral
Trismus (difficulty opening mouth)	Irritation/spasm of the medial pterygoid (pterygoid muscle) adjacent to the abscess
"Hot-potato" / muffled voice	Soft palate oedema, painful swallowing — voice sounds as if mouth full of hot food
Odynophagia / dysphagia, drooling of saliva	Severe pain on swallowing
Uvula pushed to the opposite (contralateral) side	Bulging peritonsillar mass displaces uvula
Bulging, congested soft palate above the tonsil; tonsil pushed down and medially	Pus in supratonsillar space
Foetor oris (foul breath), fever, malaise	Infection / anaerobes
Ipsilateral tender cervical lymphadenopathy (jugulodigastric node)	Regional spread
Torticollis / neck held towards affected side	Splinting of neck muscles

High-yield triad most tested: Trismus + uvular deviation to opposite side + hot-potato voice. Trismus distinguishes PTA from simple tonsillitis. Examination is itself difficult because of trismus.

The classic exam descriptor: "medially and downward displaced tonsil with the uvula deviated to the contralateral side."

Diagnosis & investigation of choice

PTA is largely a clinical diagnosis based on the above findings. Investigations are confirmatory or for ruling out differentials.

Diagnostic approach:

1. Clinical examination — unilateral bulge, uvular deviation, trismus → presumptive PTA.
2. Needle aspiration of the point of maximum bulge — it is both diagnostic (confirms pus) and therapeutic. Aspiration of pus confirms the diagnosis.
3. Contrast-enhanced CT neck — investigation of choice when diagnosis is uncertain, when distinguishing from parapharyngeal abscess, in children, or where examination is limited by trismus. Shows a rim-enhancing hypodense collection.
4. Intraoral / transcervical ultrasound — useful, radiation-free, can differentiate cellulitis (peritonsillitis) from a drainable abscess and guide aspiration.
5. Pus culture & sensitivity; throat swab; CBC (leucocytosis with neutrophilia); monospot/heterophile if infectious mononucleosis suspected (bilateral, membranous, hepatosplenomegaly).

High-yield: Needle aspiration is both diagnostic and therapeutic. CECT neck is the imaging investigation of choice when the diagnosis is in doubt or to exclude parapharyngeal extension.

Management

Management has three pillars: drainage of pus + antibiotics + supportive care, followed by the interval tonsillectomy decision.

Stepwise emergency management

Secure airway & assess → IV access + rehydration → analgesia → drain the pus (aspiration or I&D) → IV broad-spectrum antibiotics with anaerobic cover → steroids → plan tonsillectomy decision

1. Drainage — aspiration vs incision & drainage (I&D)

This is the most asked controversy.

Feature	Needle aspiration	Incision & Drainage (I&D)
Technique	Wide-bore needle at point of max bulge	Stab incision + sinus forceps to break loculi
Site	Point of maximum bulge, usually just lateral to the junction of an imaginary line	Safe area – above upper pole, at junction of horizontal line through base of uvula & vertical line through anterior pillar
Invasiveness	Less invasive, can be repeated, less pain	More definitive, ensures complete evacuation
Recurrence	Slightly higher; may need repeat aspiration	Lower
Anaesthesia	Local spray	Local
Evidence	Comparable efficacy to I&D in most studies	Preferred for large/multiloculated abscess

High-yield: The classic incision site is in the region of the most prominent bulge / safe zone above the upper pole, at the point where a horizontal line through the base of the uvula meets a vertical line along the anterior faucial pillar. Incise no deeper than necessary to avoid the internal carotid artery lying laterally.

Needle aspiration and I&D have broadly equivalent outcomes; aspiration is increasingly first-line because it is simpler and equally effective. Failure to improve in 24 hours → repeat drainage / consider abscess tonsillectomy or CT to exclude deeper spread.

2. Antibiotics

• Empirical IV therapy with anaerobic cover essential.
• First line: Amoxicillin–clavulanate (co-amoxiclav) OR penicillin + metronidazole.
• Penicillin allergy → clindamycin.
• Step down to oral once improving; total ~10–14 days.

3. Adjuncts

• Steroids (single dose dexamethasone) reduce pain, trismus and improve early recovery.
• IV fluids, analgesia (paracetamol), warm saline gargles after drainage, oral hygiene.

4. Tonsillectomy — abscess (hot/à chaud) vs interval

This is the key conceptual debate.

Type	Timing	Notes
Quinsy / abscess tonsillectomy ("hot tonsillectomy", tonsillectomy à chaud)	At the time of acute infection	Done in selected centres; drains abscess + removes tonsil in one sitting. Higher bleeding risk but avoids second admission. Indicated if recurrent or if drainage difficult.
Interval tonsillectomy	4–6 weeks after the acute episode settles	Traditional approach; allows inflammation to subside, technically safer and less bleeding.

High-yield: Interval tonsillectomy is classically done 4–6 weeks after the acute quinsy resolves. Indications to recommend tonsillectomy after PTA: recurrent PTA, a previous history of recurrent tonsillitis, complications, or age >40 with first episode (to exclude underlying neoplasm). A single PTA episode in a patient with no prior tonsillitis does not mandate tonsillectomy.

Mnemonic for tonsillectomy indications after quinsy — think "R-R-C": Recurrence, Recurrent tonsillitis history, Complications.

Complications

If untreated or inadequately drained, infection spreads along fascial planes:

PTA → parapharyngeal abscess → mediastinitis / vascular complications

Key complications (examinable list):

• Parapharyngeal abscess – the commonest spread; pus tracks laterally through the superior constrictor.
• Retropharyngeal abscess and descending necrotising mediastinitis (life-threatening).
• Airway obstruction due to oedema – the most immediate danger.
• Aspiration pneumonia / lung abscess if abscess ruptures spontaneously into the airway.
• Lemierre syndrome – septic thrombophlebitis of the internal jugular vein caused by Fusobacterium necrophorum, with septic emboli to lungs; classic and high-yield association with anaerobic PTA/oropharyngeal infection.
• Carotid artery erosion / rupture (catastrophic haemorrhage) – risk during over-deep incision.
• Jugular vein thrombosis, septicaemia, post-streptococcal sequelae (rheumatic fever, glomerulonephritis).

High-yield: Lemierre syndrome = internal jugular vein septic thrombophlebitis by Fusobacterium necrophorum — link it whenever a question mentions oropharyngeal anaerobic infection with lung septic emboli.

Key differentials — deep neck space abscesses (the recurring NEET PG comparison)

The examiner's favourite is to make you distinguish PTA from parapharyngeal and retropharyngeal abscess. Learn this table cold:

Feature	Peritonsillar (Quinsy)	Parapharyngeal abscess	Retropharyngeal abscess
Space	Between tonsil capsule & superior constrictor	Lateral pharyngeal (pharyngomaxillary) space	Behind pharynx, anterior to prevertebral fascia
Typical age	Young adults/adolescents	Any; often dental/tonsillar source	Children < 5 yrs (lymph nodes of Henle)
Bulge / swelling	Medial bulge, tonsil pushed down-medial, uvula deviated	Swelling behind angle of jaw / lateral neck; tonsil pushed medially with normal medial mucosa	Midline / paramedian bulge of posterior pharyngeal wall
Trismus	Marked	Marked (pterygoid involvement)	Usually absent
Torticollis / neck stiffness	Mild	Present	Present; child holds neck rigid
Source	Tonsillitis	Tonsil, teeth, parotid	Suppuration of retropharyngeal nodes (children); spine/foreign body (adults)
Key danger	Airway, Lemierre	Carotid sheath – great vessels, CN IX–XII	Airway, mediastinitis, spread
Imaging	CECT if doubtful	CECT neck	Lateral neck X-ray – widened prevertebral soft tissue; CECT

High-yield differentiator: In parapharyngeal abscess, the tonsil is pushed medially but the medial pharyngeal wall mucosa is normal and swelling is mainly external (behind the jaw) — unlike PTA where the peritonsillar mucosa itself bulges. Retropharyngeal abscess is a disease of young children with a posterior pharyngeal wall bulge and is best screened on lateral soft-tissue neck X-ray (increased prevertebral soft tissue width).

Other differentials to keep in mind: acute tonsillitis (bilateral, no trismus, uvula central), peritonsillitis/cellulitis (no drainable pus on aspiration), infectious mononucleosis (bilateral, membrane, lymphadenopathy, hepatosplenomegaly), and tonsillar/oropharyngeal malignancy (especially unilateral persistent enlargement in older adults — a reason to biopsy/remove).

Recently asked / exam angle

• Single most common organism in PTA → Group A beta-haemolytic Streptococcus (S. pyogenes); infection is polymicrobial with anaerobes (Fusobacterium).
• "Hot-potato voice + trismus + uvular deviation" clinical vignette → diagnosis: peritonsillar abscess.
• Site of incision/drainage → safe zone at upper pole, junction of horizontal line through base of uvula and vertical line through anterior pillar; needle aspiration is diagnostic + therapeutic.
• Interval tonsillectomy timing → 4–6 weeks after acute episode.
• Differentiate PTA vs parapharyngeal vs retropharyngeal abscess — table-based MCQ (age, bulge location, trismus, X-ray vs CT).
• Cause of trismus in quinsy → medial pterygoid muscle irritation.
• Lemierre syndrome — Fusobacterium necrophorum, IJV thrombophlebitis — frequently linked.
• Glands implicated in pathogenesis → Weber glands (explains PTA after tonsillectomy).
• Imaging of choice when in doubt → CECT neck; for retropharyngeal in children → lateral neck radiograph.
• Why uvula deviates to the opposite side, and the direction the tonsil is displaced (down and medial).

Rapid revision

1. Quinsy = pus between tonsillar capsule and superior constrictor, commonest at the upper pole.
2. Pathogenesis linked to obstructed Weber glands; progression: tonsillitis → peritonsillitis → abscess.
3. Commonest single organism Strep pyogenes; infection polymicrobial with anaerobes (Fusobacterium).
4. Classic triad: trismus + hot-potato voice + uvula deviated to opposite side; tonsil pushed down and medially.
5. Trismus (from medial pterygoid spasm) distinguishes PTA from plain tonsillitis.
6. Referred otalgia via CN IX; foetor oris, ipsilateral jugulodigastric node, fever.
7. Diagnosis is clinical; needle aspiration is both diagnostic and therapeutic; CECT neck when in doubt.
8. Treat with drainage + co-amoxiclav (or penicillin + metronidazole) + steroids + fluids.
9. Drainage options: needle aspiration ≈ I&D in efficacy; incise in the safe zone to avoid the carotid.
10. Interval tonsillectomy at 4–6 weeks; indicated for recurrence, prior recurrent tonsillitis, or complications.
11. Complications: parapharyngeal/retropharyngeal abscess, mediastinitis, airway obstruction, Lemierre syndrome, carotid erosion.
12. Retropharyngeal abscess = children, posterior wall bulge, diagnosed on lateral neck X-ray; parapharyngeal = swelling behind angle of jaw with normal medial mucosa.