Definition

A peritonsillar abscess is a collection of pus within a pocket that forms near one of the tonsils at the back of the throat. Tonsils are pink, oval-shaped organs located on each side at the back of your throat. A peritonsillar abscess can cause pain, and swelling, and, in severe cases, can obstruct the throat. This obstruction can make swallowing, speaking, and even breathing difficult. 

A peritonsillar abscess is caused by a bacterial infection, typically a complication of untreated strep throat or tonsillitis (inflammation of the tonsils). Peritonsillar abscesses are relatively rare and are more likely to occur in young adults, teenagers, and children. Cases often occur at the beginning or end of winter when illnesses like strep throat and tonsillitis are most common.

Causes

A peritonsillar abscess is most often caused by complications from tonsillitis. The bacteria responsible for a peritonsillar abscess are similar to those that cause strep throat, specifically Group A Streptococcus. Streptococcal bacterial infections most frequently affect the soft tissues around the tonsils and usually only on one side. The tissue is then invaded by anaerobic bacteria (bacteria that can live without oxygen), which enter through nearby glands, leading to pus accumulation in the tissue. 

The incidence of peritonsillar abscesses has decreased with the use of antibiotics to treat strep throat and tonsillitis. Additionally, infectious mononucleosis (commonly called mono) can cause a peritonsillar abscess, as can dental and gum infections. In rarer cases, a peritonsillar abscess might occur without a preceding infection, typically due to inflammation of the Weber glands, which are located under the tongue and produce saliva.

Risk factor

A peritonsillar abscess usually arises from tonsillitis. Other conditions and diseases that can increase the risk include:

• Dental infections (such as periodontitis and gingivitis)
• Frequent and prolonged tonsillitis
• Infectious mononucleosis
• Smoking
• Chronic lymphocytic leukemia (CLL)
• Tonsil stones or calcified deposits in the tonsils (tonsilloliths)

Symptoms

The first symptom of a peritonsillar abscess is typically a sore throat. Other symptoms that develop as the abscess forms include:

• Inflamed and swollen areas in the mouth and throat, usually on one side
• The uvula (the tissue structure hanging in the middle of the throat) may be pushed away from the swollen side
• Swollen and tender lymph nodes in the neck
• Painful swallowing
• Fever and chills
• Jaw (trismus) and neck (torticollis) stiffness, making it difficult to open the mouth fully
• Ear pain on the same side as the abscess
• Muffled voice, often described as a "hot potato voice" (sounding like there is a hot potato in the mouth)
• Difficulty swallowing saliva
• Headache
• Sore throat (usually worse on one side)
• Bad breath

Diagnosis

To diagnose a peritonsillar abscess, a doctor will start by asking about your symptoms and any history of tonsillitis. The doctor will then perform a physical examination, focusing on the inside of the mouth and throat. They might use a small light and a tongue depressor to assist the examination. Swelling and redness on one side of the tonsils may indicate an abscess. The doctor may also use a needle to puncture the swollen area to check for pus. If pus is present, a sample may be sent to a laboratory to identify the bacteria.

 Laboratory tests and X-rays are not often used to diagnose a peritonsillar abscess. Sometimes, an X-ray, CT scan, or ultrasound is performed to rule out other upper airway diseases, such as:

• Epiglottitis: inflammation of the epiglottis (the tissue structure in the throat that prevents food from entering the windpipe).
• Retropharyngeal abscess: a pus-filled pocket that forms behind the soft tissue in the back of the throat (similar to a peritonsillar abscess but in a different location).
• Peritonsillar cellulitis: an infection of the soft tissue around the tonsils.

Management

In managing a peritonsillar abscess, the doctor's primary concern will be the airway and your ability to breathe. If you have difficulty breathing due to a blocked throat, the first step may be to insert a needle into the pus pocket to drain it, allowing you to breathe comfortably.

The main treatment principle for a peritonsillar abscess is to drain the pus. If the abscess does not obstruct the airway, the doctor will choose a treatment method to minimize pain. You will receive local anesthesia injected into the skin over the abscess, and if necessary, pain relief and sedation (sleep medication) will be administered through an IV in your arm. 

Possible treatment options include:

• Needle aspiration: carefully inserting a needle into the abscess and drawing out the pus with a syringe.
• Incision and drainage: using a scalpel to make a small cut in the abscess so the pus can drain out.
• Tonsillectomy: a surgical procedure to remove the tonsils, which may be necessary if drainage procedures are not tolerable or if there is a history of frequent tonsillitis.

Additionally, the doctor will prescribe antibiotics. The first dose may be given through an IV. Penicillin is the best antibiotic for this type of infection, but if you are allergic, inform your doctor so an alternative like erythromycin or clindamycin can be used.

Complications

If treated quickly and appropriately, a peritonsillar abscess usually resolves without further problems. However, if left untreated, the abscess can cause more serious issues. Most complications occur in people with diabetes, weakened immune systems (such as those with AIDS, individuals taking immunosuppressive medications, or cancer patients), or those unaware of the severity of the condition and do not seek treatment. Major complications of a peritonsillar abscess include:

• Airway obstruction
• Bleeding
• Dehydration due to difficulty swallowing
• Infection spreading to the tissues under the breastbone
• Pneumonia
• Meningitis (inflammation of the membranes surrounding the brain and spinal cord)
• Endocarditis (infection of the inner lining of the heart)
• Sepsis (bacterial infection in the bloodstream that can spread throughout the body)
• Death

Prevention

There is no sure way to prevent a peritonsillar abscess, but you can reduce your risk by:

• Avoiding smoking
• Treating tonsillitis before it worsens (antibiotic treatment as prescribed by a doctor can help prevent complications)
• Treating mouth, tooth, and gum infections
• Maintaining good oral hygiene

When to see a doctor?

Consult a doctor if you have tonsillitis and experience symptoms of a peritonsillar abscess. If you have a sore throat and difficulty swallowing, breathing, or speaking, drooling, or any other signs of potential airway obstruction, you should go to the emergency room immediately.