Peritonsillar Abscess (Quinsy)

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

The most commonly accepted theory is that an episode of acute exudative tonsillitis is untreated or inadequately treated and progresses to abscess formation. It usually starts with acute follicular tonsillitis, progresses to peritonsillitis, and results in formation of a peritonsillar abscess. It can arise without previous tonsillitis.

An alternative theory suggests involvement of the Weber glands.² These are a group of salivary glands, immediately above the tonsillar area in the soft palate. They are thought to play a minor role in clearing any trapped debris from the tonsillar area. Tissue necrosis and formation of pus produce an abscess between the tonsillar capsule, lateral pharyngeal wall, and supratonsillar space. There is scarring and obstruction of the ducts that drain the glands. They swell and progress to abscess formation.

• Tonsillitis is predominantly a disease of children. Peritonsillar abscess usually affects teenagers and young adults but can occur in younger children.¹
• It is most common in November to December and April to May, coinciding with the highest incidence of streptococcal pharyngitis and exudative tonsillitis.³
• A survey in 2002 of ENT consultants in the UK received only a 50% response rate but found that the average ENT department treats 29 cases a year, 94% of them as inpatients. The average length of stay was 2 days.⁴

• Culture nearly always shows a mixed flora. Most common organisms include:
  • Group A beta haemolytic Streptococcus pyogenes (usually the predominate organism)³
  • Staphylococcus aureus
  • Haemophilus influenzae
  • Anaerobic organisms including Prevotella, Porphyromonas, Fusobacterium and Peptostreptococcus spp.
• Peritonsillar abscess can also be a complication of infectious mononucleosis.⁶

• Severe throat pain which may become unilateral
• Fever
• Drooling of saliva
• Foul smelling breath
• Swallowing may be painful
• Trismus (difficulty opening the mouth)
• Altered voice quality ('hot potato voice') due to pharyngeal oedema and trismus
• Earache on the affected side
• Neck stiffness symptoms
• Headache and general malaise

• Examination may be difficult as trismus may make it difficult to open the mouth in up to two thirds of cases.
• Breath is fetid.
• There may be drooling and salivation.
• Look for a temperature.
• Tender, enlarged ipsilateral cervical lymph nodes.
• Torticollis may be present.
• There is unilateral bulging usually above and lateral to one of the tonsils; occasionally the bulging is inferiorly.
• There is medial or anterior shift of the affected tonsil and the tonsil may be erythematous, enlarged and covered in exudate.
• The uvula is displaced away from the lesion.
• Examine for signs of dehydration.
• Compromise of the airway is rare.
• Spontaneous rupture of the abscess into the pharynx can rarely occur and can lead to aspiration.⁵

• The diagnosis is clinical.
• CT scanning is not generally needed but may be used in atypical presentations such as an inferior pole abscess, or if the patient is high risk for a drainage procedure (e.g. bleeding disorder). It may also be helpful to guide drainage in difficult cases.
• Screening for infectious mononucleosis may be helpful.⁶

Medical

• Intravenous fluids may be required to correct dehydration.
• Analgesia should be prescribed.
• Intravenous antibiotics give higher blood levels than oral therapy and are usually used.
• Penicillin, cephalosporins, amoxicillin + clavulanic acid and clindamycin are all appropriate antibiotics.¹
• In rare cases where there may be associated toxic shock syndrome, intravenous immunoglobulins are sometimes used.¹
• Studies have also shown that the use of single dose intravenous steroids as well as antibiotics may be beneficial.⁸ They may help reduce symptoms and speed recovery.³

Surgical

• Antibiotics alone are not usually sufficient as treatment.⁹
• Needle aspiration can be performed to confirm the diagnosis and remove some of the pus. Sedation may be needed.
• The pus should be sent for gram stain and culture and sensitivity testing. Rapid antigen detection tests can also be used to identify the causative organism(s).
• Complete aspiration can then be attempted or incision and drainage (which may be superior) can be performed.⁹ Sedation and local anaesthesia or general anaesthesia may be required.
• Interval tonsillectomy is usually carried out if there is a background of chronic or recurrent tonsillitis.
• Some surgeons advocate acute (immediate) tonsillectomy as a treatment for peritonsillar abscess. There is controversy surrounding this. The acute infection may make the site more vascular and hence more likely to bleed. Increased risk of haemorrhage has been disputed.^10,11
• Tonsillectomy is discussed in more detail in the separate article 'Tonsillitis - Acute and Chronic'.

• The abscess can spread to the deeper neck tissues and can result in necrotizing fasciitis.^12,1 Infection can spread from the parapharyngeal space through the anatomical planes to cause mediastinitis, pericarditis and pleural effusions.¹³
• Airway compromise is rare.
• Recurrence of peritonsillar abscess can occur.
• Haemorrhage may follow tonsillectomy.
• Death can occur from aspiration, airway obstruction, erosion into major blood vessels or extension to the mediastinum.⁵

• The rate of recurrence is around 10 to 15%; 90% of those that recur do so within a year.
• Recurrence can follow tonsillectomy.

• A recent retrospective cohort study looked at the protective effects of antibiotics against serious complications of common respiratory tract infections in the UK, including peritonsillar abscess after sore throat. It found that serious complications were rare and the number needed to treat was over 4000. It concluded that antibiotics are not justified to reduce the risk of serious complications for upper respiratory tract infection.¹⁴
• Another study in the Netherlands suggested that penicillin prescription in sore throat may reduce the risk of streptococcal sequelae.¹⁵
• 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.¹⁶
• The guidance regarding antibiotics and sore throat is further discussed in the articles 'Sore Throat' and 'Tonsillitis, Acute and Chronic'.