Peritonsillar abscess

Synonym: quinsy

What is peritonsillar abscess?

Peritonsillar abscess is a complication of acute tonsillitis. Tonsillitis is inflammation of the pharyngeal tonsils (see the separate Tonsillitis article).¹ In peritonsillar abscess, there is pus trapped between the tonsillar capsule and the superior pharyngeal constrictor muscle.²

Pathophysiology

It was previously accepted that peritonsillar abscess follows tonsillitis and peritonsillar cellulitis. However, studies have shown it frequently arises in the absence of tonsilitis.

An alternative theory suggests involvement of the Weber glands.³ This group of salivary glands are immediately above the tonsillar area in the soft palate. The saliva produced clears trapped debris from the tonsillar area. Obstruction of the salivary ducts that drain the glands may contribute to peritonsillar abscess formation.

How common is peritonsillar abscess? (Epidemiology)

Peritonsillar abscess usually affects teenagers and young adults but can occur in younger children.² This picture may, however, be changing. One Israeli study found a distinct cohort of people over 40 suffering from peritonsillar abscess who had more severe symptoms and a more prolonged course. Smoking was thought to be a risk factor.⁴ An American study reported an incidence of 30 per 100,000 among patients who are 5-59 years of age. It is rare under the age of 5.⁵

Peritonsillar abscess occurs in only 2% of patients with tonsilitis. ⁶

Causative organisms

• Culture nearly always shows a mixed flora. Most common organisms include:⁷

  • Streptococcus pyogenes (usually the predominant organism). Commonly referred to as Group A strep (group A Streptococcus).

  • Staphylococcus milleri

  • Anaerobic organisms including Prevotella spp., and Fusobacterium spp.

• Peritonsillar abscess can also be a complication of infectious mononucleosis.⁸

History⁵²

• Odynophagia. Severe throat pain which is worse on one side.

• Fever.

• Swallowing may be very painful, which may lead to the drooling of saliva.

• Trismus (difficulty opening the mouth).

• Altered voice quality ('hot potato voice') due to pharyngeal oedema and trismus.

• Ipsilateral otalgia.

• Feeling unwell with malaise, body aches, and headache.

Examination⁵²

• The patient often looks unwell.

• There is unilateral swelling of the peritonsillar area. This appears as a unilateral bulge in the soft palate with overlying erythema and may demonstrate exudate. This may displace the ipsilateral tonsil inferiorly or anteriorly.

• The uvula is displaced away from the abscess.

• There may be drooling and salivation.

• Fetor (foul smelling breath).

• Tender, enlarged ipsilateral cervical lymph nodes.

• The person usually has a fever.

• Examine for signs of sepsis and dehydration.

• Assess for signs of airway compromise.²

Diagnosing peritonsillar abscess (investigations)

• The diagnosis is clinical, based on history and examination.

• CT or MRI scanning is not generally needed but may be used in atypical presentations such as an inferior pole abscess, to guide drainage in difficult cases or if there is concern infection has spread beyond the peritonsillar space.²

• Ultrasound may be helpful in differentiating a peritonsillar abscess from peritonsillitis. It may also help to locate the optimal site for drainage.²

• Evidence supporting the use of screening for infectious mononucleosis is equivocal. One study found that only 4% of quinsy patients tested positive for infectious mononucleosis, all of them under the age of 30.

Management of peritonsillar abscess

Management is based on the use of antibiotics, drainage, analgesia and ensuring supportive measures such as hydration. Patients with suspected peritonsillar abscess should be referred to and seen by an ENT specialist that day.²⁶

Medical treatment

• Analgesia and antipyretics.

• Ensure hydration. Intravenous fluids may be required to correct dehydration.

• Intravenous antibiotics give higher blood levels than oral therapy and are usually used initially until the patient can tolerate oral medication and is well enough to do so.

• Antibiotics need to cover the broad spectrum of Gram-positive, Gram-negative and anaerobic organisms. Amoxicillin with metronidazole is commonly recommended.²⁵ Antibiotic therapy should ideally be commenced after microbiology samples have been taken. A 10-14 day course should be prescribed.

• Studies have also shown that the use of single-dose intravenous steroids as well as antibiotics reduces pain and improves oral intake in the 24 hours after administration compared to patients who did not receive adjuvant corticosteroids. Empirical use of adjuvant steroids is not recommended until further studies have been undertaken.²⁹

Surgical treatment

• Drainage of the abscess is necessary.¹⁰ Needle aspiration, incision and drainage and quinsy tonsillectomy are all considered acceptable for the surgical management of acute peritonsillar abscess. An evidence-based review failed to differentiate between them in terms of effectiveness and recurrence rates.¹¹

• Ultrasound-guided aspiration is occasionally used if surgery is unsuccessful or the abscess is in a location that is difficult to reach.¹²

• Immediate tonsillectomy may be considered in the paediatric population who are potentially more likely to have recurrent tonsillitis and undergo general anaesthesia for drainage, or those with strong indicators for tonsillectomy such as recurrent tonsillitis,² A case series review found no significant differences in total hospital days, blood loss, operative time, or postoperative complications between immediate tonsillectomy and interval tonsillectomy in the treatment of paediatric peritonsillar abscess.¹³

• Tonsillectomy is discussed in more detail in the separate Tonsillitis article.

Complications of peritonsillar abscess

• The abscess can spread to the deeper neck tissues and can result in necrotising fasciitis.¹⁴ Other complications can include retropharyngeal abscess, laryngeal oedema leading to airway compromise, rarely pneumonia or lung abscess following aspiration of a ruptured abscess, and sepsis.⁵

• Airway compromise is rare.

• Erosion into major blood vessels or extension to the mediastinum may be fatal.¹⁵

Prognosis

• The rate of recurrence is poorly defined and has been reported as between 1-22%.⁵¹⁶

• Recurrence can follow tonsillectomy but is rare.¹⁷

Prevention of peritonsillar abscess

• A Cochrane review found that the benefits of treating sore throats with antibiotics was moderate and that many patients would need to be treated to prevent one case of quinsy.¹⁸ The number needed to treat (NNT) was estimated by a Canadian study as being about 30.¹⁹

• A fall of 50% in the prescribing of antibiotics to children in English general practice has not been accompanied by an increase in hospital admissions for peritonsillar abscess.²⁰

• The guidance regarding antibiotics and sore throat is further discussed in the separate Sore throat and Tonsillitis articles.