Peritonsillar Abscess – Pathophysiology, Causes and Prevention


Peritonsillar abscess, or Quinsy are typically a complication of tonsillitis. They most often are caused by “strep throat” bacteria (group A beta-hemolytic streptococci). The peritonsillar space lies between each tonsil and the wall of the throat. An infection can cause a pus-filled swelling (abscess) to develop in this space.

A peritonsillar abscess can infect the roof of the mouth, the neck, and the lungs if it is not treated immediately. The tonsil that is closest to the swelling may move into the middle of your neck, and the uvula (the tissue flap that hangs in the back of your throat) may shift from the centre to the side of your throat that is not affected. In extreme cases, the swelling may block your airway or make breathing difficult.

The most common age groups for peritonsillar abscesses are older children, adolescents, and young adults. Because tonsillitis is now frequently treated with medicines, which kill the infection-causing bacteria, they are less prevalent than they once were.


The incidence of PTA in the United States is about 30 cases per 100,000 people per year, representing about 45,000 new cases each year. No accurate data are available internationally. Although tonsillitis is a disease of childhood, only one third of PTA cases are found in this age group. The age of patients with the condition is variable, ranging from 1 to 76 years, with the highest incidence in persons aged 15-35 years. No sexual or racial predilection has been established.

In a retrospective cohort study of 427 patients with PTA, researchers investigated how the characteristics of PTA may have changed over time. The results led the authors to conclude that PTA currently tends to affect an older population than it once did, that its course in older individuals has become longer and worse, and that smoking may be a predisposing factor in its development.

Researchers also found that the institution of protective measures as a result of the COVID-19 pandemic led to a 43% reduction in the incidence of peritonsillar infection from the 2017-2019 period to 2020; however, the cases that did occur tended to have a longer recovery period, and there were more PTAs. A study from the United States did not find the pandemic to have a significant effect on the incidence of PTA in pediatric otolaryngology practice.

Peritonsillar Abscess Pathophysiology

The exact pathophysiology of peritonsillar abscess formation remains unknown to date. The most accepted theory is that an infection develops in crypta magna that then spreads beyond the confines of the tonsillar capsule, initially causing peritonsillitis and then developing into a peritonsillar abscess. Another proposed mechanism is necrosis and pus formation in the capsular area which then obstructs the webers glands, resulting in abscess formation. These are minor salivary glands in peritonsillar space which are responsible for clearing debris from the tonsillar area. The occurrence of peritonsillar abscess in patients who have undergone tonsillectomy further support this theory.

Causative organisms

Peritonsillar abscess is usually a complication of tonsillitis and thus has a similar clinical presentation and infective etiology. The most common pathogens are those that cause tonsillitis, namely beta-hemolytic Streptococci, with Staphylococcus aureusStreptococcus pneumoniae, and Haemophilus influenzae also common causes.

  • Infection extends through the fibrous capsule of the tonsil entering the peritonsillar space, located between the tonsillar capsule and superior pharyngeal constrictor muscle. Further extension may occur into the parapharyngeal, masticator, and/or submandibular spaces.
  • These abscesses tend to form more during the winter and spring. Not only abscesses, strep throat and tonsillitis are also common during these seasons.
  • Rarely is the case in which peritonsillar abscesses form without tonsilitis. An abscess forms when the infection of the tonsils breaks out of a tonsil and spread to the surrounding area.
  • Another condition that can cause peritonsillar abscess is mononucleosis. This also causes tooth and gum infections.

Bilateral Peritonsillar Abscesses

Symptoms of Peritonsillar Abscess

One or both tonsils become infected. The infection most often spreads to around the tonsil. It can then spread down into the neck and chest. Swollen tissues can block the airway. This is a life-threatening medical emergency.

The abscess can break open (rupture) into the throat. The content of the abscess can travel into the lungs and cause pneumonia.

Symptoms of peritonsillar abscess include:

  • Fever and chills
  • Severe throat pain that is usually on one side
  • Ear pain on the side of the abscess
  • Difficulty opening the mouth, and pain with opening the mouth
  • Swallowing problems
  • Drooling or inability to swallow saliva
  • Facial or neck swelling
  • Fever
  • Headache
  • Muffled voice
  • Tender glands of the jaw and throat
  • Neck stiffness

Complications of Peritonsillar Abscess

  • Airway obstruction
  • Aspiration pneumonitis or lung abscess secondary to peritonsillar abscess rupture
  • Extension of infection into the deep tissues of the neck or superior mediastinum
  • Life-threatening hemorrhage secondary to erosion or septic necrosis into carotid sheath
  • Poststreptococcal sequelae, such as glomerulonephritis and rheumatic fever, when infection is caused by group A streptococcus
  • Sepsis (infection in the blood)

Risk factors

This problem is more common in males and people aged 20 to 40 years of age.

Other things that may raise the risk of this problem are:

  • Pharyngitis or tonsillitis caused by strep bacteria or another bacteria
  • Mononucleosis
  • Recent throat infection or dental infection
  • Periodontal disease
  • Smoking

How to diagnosis peritonsillar abscess?

Your healthcare provider will examine you and look inside your mouth and throat. You will be asked about your symptoms and health history. Tests or procedures may be done as well, including those listed below:

Throat swab: This test checks for infection. It is done by wiping a sterile cotton swab in the back of the throat. The swab can be used for an immediate result. It can also be sent to a lab for a culture if needed.

Blood tests: These might be done to check how your body is responding to the infection.

Ultrasound or CT scans: These tests provide images of the abscess. They also help rule out other problems.

Needle aspiration: This procedure removes a sample of pus from the abscess with a needle. The sample is then sent to a lab to check for infection. Whenever possible, all the pus is removed from the abscess.


In most cases, a peritonsillar abscess requires surgical drainage and antibiotics. If you get more than one peritonsillar abscesses, you may need a tonsillectomy.


Your healthcare provider will prescribe antibiotics, which may be given intravenously (through a vein) or taken in pill form. Common oral (by mouth) antibiotics include penicillin, amoxicillin, cephalosporin and clindamycin.

Peritonsillar abscess drainage

In most cases, your healthcare provider will drain the peritonsillar abscess. To do this, they’ll make an incision in the abscess to release the fluid inside of it.


If you have recurrent (repeated) peritonsillar abscesses, your healthcare provider may recommend a tonsillectomy. During this procedure, your tonsils are surgically removed.

Does a peritonsillar abscess need surgery?

In most cases, yes. If it’s the first time you’ve had a peritonsillar abscess, your healthcare provider will likely drain the abscess and prescribe antibiotics. However, if you’ve had recurring (repeated) peritonsillar abscesses, they may recommend a tonsillectomy.

How to prevent peritonsillar abscess?

One of the best ways to prevent quinsy is to reduce your risk of developing tonsillitis.

You can help do this by:

  • Avoiding close contact with people who have viral or bacterial infections that cause tonsillitis
  • Regularly washing your hands with soap and warm water
  • Not sharing glasses or utensils with people who are ill

Smoking may increase your risk of quinsy, so stopping smoking may reduce your chances of getting it.

Using antibiotics to treat viral tonsillitis doesn’t significantly reduce the risk of quinsy and isn’t routinely recommended.

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