Definition: Previously known as quinsy, peritonsillar abscess (PTA) is the suppurative end-point of bacterial infection that results in the development of pus between the palatine tonsil and its capsule.


  • Occurs mainly in young adults: 20- 40s
  • Most common deep space neck infection
  • Incidence ranges from 1-3/10,000 per year


  • In most textbooks, it is taught that PTA is the end-point on the pharyngitis continuum where bacterial pharyngitis progress to tonsillitis developing into peritonsillar cellulitis then ultimately abscess formation.
  • Controversy: no real evidence to support the above proposed mechanism and there exist various inconsistencies in the above process (Passy 1994, Powell 2013)
    • Peak incidence of acute pharyngitis occurs ages 5-15, peak incidence of PTA ages 20-40. If they are on the same spectrum, there should be an age overlap.
    • Both acute pharyngitis and PTA have peak symptoms at 3-5 days. If PTA is a complication from the progression of acute pharyngitis, it would make sense that there is a time lag between the peak onset of pharyngitis and PTA.
    • Samples of tonsils from quinsy tonsillectomies are not found to have exudates on tonsils. (Passy 1994)
  • New proposed mechanism: bacterial infection of weber’s glands. Weber’s glands are a series of salivary glands that penetrate the posterior aspect of the palatine tonsillar capsule extending through the middle and distributed mainly on the superior surface of the palatine tonsils. They act to aid in the digestion of food caught in the tonsillar crypts. (Passy 1994, Powell 2013)
  • Supporting this is the geography of abscess formation: majority of PTAs develop on the superior aspect of the tonsil.


  • Fever
  • Sore throat
  • Dysphonia
  • Dysphagia

Physical Exam Findings: Majority of PTAs will have abscess collection at superior pole of tonsils so these classic exam findings will be visualized in the oropharynx:

  • Unilateral swelling of tonsil
  • Edematous uvula that deviates towards the normal tonsil
  • Erythematous elevated soft palate
  • Patient can appear uncomfortable
  • Muffled/hot-potato voice
  • Trismus (In PTA, trismus should be minimal after provision of adequate analgesia. Suspect deeper neck infection if trismus persist after sufficient pain management.)
  • Cervical lymphadenopathy

Physical Exam Diagnosis

  • Most PTAs can be diagnosed by physical exam findings. However, it can be difficult to differentiate between PTA versus tonsillar cellulitis as the two can present similarly.
  • Inferior pole PTA (20%) will often lack the classic exam findings.
  • Landmark guided needle aspiration of presumed area of abscess carries diagnostic sensitivity ranging from 64-78% with specificity of 50% (Costantino 2012, Scott 1999)

Ultrasound Diagnosis

  • Ultrasound significantly increases the sensitivity and specificity of diagnosis. In a recent study by Costantino et al demonstrated ultrasound diagnostic sensitivity to 100% (Costantino 2012).
  • Provide patient with both adequate systemic and topical analgesia such as atomized benzocaine or lidocaine
  • A 5-10mHz curved array endocavitary probe should be used with probe cover. Tonsils should be scanned both in longitudinal and transverse planes.
  • A PTA will appear as either a hypoechoic (lacking echogenicity-dark) or complex cystic mass (dark with dirty shadowing). Ultrasound can also identify the location of the carotid artery, which lies only 5-25mm posteriorly and laterally. The carotid artery will appear as an anechoic (black) tubular structure that is pulsatile when color doppler is applied. (insert image of PTA with carotid artery)
  • Read More: Small Parts-ENT Ultrasound Applications (Ultrasound Guide for Emergency Physicians)

CT Scans

  • Though CT of the neck with contrast has 100% sensitivity for diagnosis of PTA, it should not be a routine test. There is a significant amount of radiation involved increasing rate of cancer by 390/million. (Powell 2012, Scott 1999)
  • CT scan should be considered in patients where alternate diagnoses are suspected (retropharyngeal abscess, Lemierre’s syndrome etc).
  • Examples of patients who may benefit from CT of the neck include patients that appear ill out of proportion to exam or in patients with severe trismus.

Initial Management: Initial management of all patients in the Emergency Department begins with A.B.Cs (airway, breathing, circulation). After establishing the patient does not require urgent or emergent airway management or significant breathing support and is hemodynamically stable, move onto the following steps for management of PTA.

Abscess drainage

  • Needle aspiration vs. I&D vs. Quinsy Tonsillectomy
    • No statistical difference in drainage success and time to return to normal diet (Johnson 2003)
    • Needle aspiration of preferred technique in ED because of decreased pain (in comparison to I&D) and necessity of hospitalization (in quinsy tonsillectomy)
  • Watch the Video: Drainage of a Peritonsillar Abscess


  • Bacteria responsible for infection unclear:
    • Powell et al looked at pus cultures from 15 different studies, extending from 1980s to 2012 showing extreme variability of organisms isolated, with rare single isolates. Cultures were more often polymicrobial reflecting common oropharyngeal microflora and hard to parse out which organism is important to development of pathology. There however are 2 standouts: Group A Streptococcus (GAS) and Fusobacterium necrophorum that were found in most polymicrobial growths.
    • Antibiotics should cover both for GAS (gram positive) as well as Fusobacterium (anaerobic)
  • Antibiotic Choices
    • Amoxicillin/clavulanic acid 875mg BID x 10 days
    • Penicillin VK 500mg QID + Metronidazole 500mg QID x 10 days
    • PCN Allergy: Clindamycin 150mg QID x 10 days
  • IV vs. PO
    • No statistical difference found between IV and PO antibiotics in the treatment of PTA in morbidity, recovery time as well as recurrence rate (Powell 2012)


  • Steroids decrease time to tolerating PO and decrease pain scores in first 24 hours (Chau 2014, Ozbek 2004)
  • Unclear which steroid is better. The only 2 clinical trials on steroids given in context of PTA used different medications but both were single dose IV steroids; one used IV methylprednisolone (2-3mg/kg up to 230mg) and the other used IV dexamethasone (10mg)

Take Home Points

  • Use ultrasound to help with diagnosis and identify abscess in relationship to carotid artery
  • Use advanced imaging (CT) in patients who have severe symptoms or are toxic appearing
  • After needle aspiration (or I&D) treat patients with 10 days of antibiotics


Chau JK, Seikaly HR, Harris JR, Villa-Roel C, Brick C, Rowe BH, Corticosteroids in peritonsillar abscess treatment: a blinded placebo-controlled clinical trial, Laryngoscope 2014 Jan;124(1):97-103. PMID: 23794382

Costantino TG, Satz WA, Dehnkamp W, Goett H. Randomized trial comparing intraoral ultrasound to landmark-based needle aspiration in patients with suspected peritonsillar abscess, Acad Emerg Med 2012 Jun;19(6):626-31. PMID: 22687177

Johnson RF, Stewart MG, Wright CC. An evidence-based review of the treatment of peritonsillar abscess, Otolaryngol Head Neck Surg 2003;128(3):332-43. PMID: 12646835

Passy V, Pathogenesis of peritonsillar abscess, Laryngoscope 1994;104(2):185-90. PMID: 8302122

Powell EL, Powell J, Samuel JR, Wilson JA, A review of the pathogenesis of adult peritonsillar abscess: time for a re-evaluation, J Antimicrob Chemother 2013;68:1941-1950. PMID: 23612569

Powell J, Wilson J.A, An evidence-based review of peritonsillar abscess, Clin. Otolaryngol 2012;37: 136-145. PMID: 22321140

Ozbek C, Aygenc E, Tuna EU, Selcuk A, Ozdem C, Use of steroids in the treatment of peritonsillar abscess, J Laryngol Otol 2004 Jun;118(6):439-42. PMID: 15285862

Scott PM, Loftus WK, Kew J, Ahuja A, Yue V, van Hasselt CA. Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis, J Laryngol Otol 1999 Mar;113(3):229-32. PMID: 10435129