Peritonsillar Abscess

Synonym: quinsy

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 lateral pharyngeal wall^[2].

Pathophysiology

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^[3]. 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. 

Epidemiology

• Tonsillitis is predominantly a disease of children. 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. Tonsillitis was not always a precursor to the condition or it sometimes occurred despite prior adequate antibiotic therapy. 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].
• It is most common in November to December and April to May, coinciding with the highest incidence of streptococcal pharyngitis and exudative tonsillitis^[2].

Causative organisms 

• Culture nearly always shows a mixed flora. Most common organisms include^[6]:
  • Streptococcus pyogenes (usually the predominant organism).
  • Staphylococcus aureus.
  • Haemophilus influenzae.
  • Anaerobic organisms including Prevotella spp., and Fusobacterium spp. 
• Peritonsillar abscess can also be a complication of infectious mononucleosis^[7].

History

• 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

• 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^[8]. 

Investigations

• 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 (eg, a bleeding disorder). It may also be helpful to guide drainage in difficult cases.
• Ultrasound may be helpful in differentiating a peritonsillar abscess from peritonsillitis. It may also help to locate the optimal site for drainage^[8]. 
• 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

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.
• Antibiotics need to cover the broad spectrum of Gram-positive, Gram-negative and anaerobic organisms. Amoxicillin with clindamycin or metronidazole are appropriate antibiotics^[5]. 
• Studies have also shown that the use of single-dose intravenous steroids as well as antibiotics may be beneficial^[10]. They may help to reduce symptoms and to speed recovery^[2].

Surgical

• Antibiotics alone are not usually sufficient as treatment. Changes in the microbiology of the causative organisms and their resistance has resulted in surgery being the preferred option in most cases^[11].
• 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^[12].
• Ultrasound-guided aspiration is occasionally used if surgery is unsuccessful or the abscess is in a location that is difficult to reach^[13].
• 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. 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^[14].
• Tonsillectomy is discussed in more detail in the separate Tonsillitis article.

Complications

• The abscess can spread to the deeper neck tissues and can result in necrotising fasciitis^[15]. 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.
• Recurrence of peritonsillar abscess can occur.
• Haemorrhage may follow tonsillectomy.
• Erosion into major blood vessels or extension to the mediastinum may be fatal^[16].

Prognosis

• The rate of recurrence is poorly defined but is around 9-22%^[17].
• Recurrence can follow tonsillectomy but is rare^[18].

Prevention

• 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^[19]. The number needed to treat (NNT) was estimated by a Canadian study as being about 30^[20].
• 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^[21].
• The guidance regarding antibiotics and sore throat is further discussed in the separate Sore Throat and Tonsillitis articles.