Peritonsillar abscess, also known as quinsy, is the localized collection of pus in peritonsillar space between the tonsillar capsule and superior constrictor muscle. It was first described in the 14th century and became more extensively known in the 20th century after the antibiotic era started.
Peritonsillar space consists of loose connective tissue between the fibrous capsule of palatine tonsils medially and superior constrictor muscle laterally. The anterior and posterior tonsillar pillar contribute to anterior and posterior limits, respectively. Superiorly, this space is related to torus tubarius, while pyriform sinus forms the inferior limit. Since this space is composed of loose connective tissue, it is highly susceptible to abscess formation following infection.
Peritonsillar abscess usually occurs following acute tonsillitis. Infectious mononucleosis can also result in abscess formation. Rarely, it may occur de novo without any prior history of a sore throat. Smoking and chronic periodontal disease could also cause quinsy.
Cultures most commonly reveal Group A beta-hemolytic streptococcus. The next most commonly found organisms include staphylococcal, pneumococcal, and hemophilic organisms. Rarely, Lactobacillus and filamentous forms like Actinomyces and Micrococcus may be present. Most of the time, the growth is mixed, with both aerobic and anaerobic organisms.
Peritonsillar abscess is a common infection of the head and neck region. With an incidence of approximately 1 in 10,000, it is the most common deep head and neck space infection that presents in the emergency department.
It is more common among the adolescent population although it can occur in any group. There is no sexual or racial predilection. In the United States, the incidence is 30 per 100,000 among patients who are 5 to 59 years of age. Peritonsillar abscess is rare below five years of age.
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.
The patient mainly complains of progressively increasing pain in the throat which is usually unilateral. There may be referred earache on the same side. Associated odynophagia (painful swallowing) is present, which in certain cases becomes so severe that the patient cannot swallow his or her saliva. This results in poor oral hygiene and oral sepsis-causing halitosis (foul breath). As the abscess size progresses, it may result in muffled speech or "hot potato" voice. Neck pain develops secondary to inflamed cervical lymph nodes. Trismus (inability to open mouth) of varying severity occurs in almost every case due to inflammation of the pterygoid muscles, which lie near the superior constrictor muscles. Other accompanying features include fever with rigors and chills, malaise, body aches, headache, nausea, and constipation.
As the inflammation proceeds, an abscess may extend to the parapharyngeal and prevertebral space, causing respiratory distress.
On examination, the patient is usually ill-looking and febrile. Clinical presentation may vary from acute tonsillitis with a minimal unilateral pharyngeal bulge to dehydration and sepsis. On local examination, there is trismus of varying degree. The tonsil is found pushed downward and medially; it blanches on applying slight pressure. The uvula is swollen and edematous and pushed to the opposite side. There is a bulge on the soft palate and anterior tonsillar pillar. Mucous may be seen overlying the tonsillar region.
Cervical lymphadenopathy is seen, usually in the jugulodigastric lymph nodes. Torticollis may be seen as the patient keeps the neck tilted on the affected side.
Diagnosis and Work Up
Diagnosis of peritonsillar abscess is usually made clinically by any of the following features:
A suitable intravenous antibiotic is started. The antibacterial spectrum should include gram-positive, gram-negative, and anaerobes. Commonly used empirical antibiotics are penicillins like ampicillin/amoxicillin in combination with metronidazole or clindamycin. (Ideally, antibiotic therapy should be started as per culture sensitivity reports). A patient is shifted to oral antibiotics once he improves and can tolerate orally.
Analgesics and antipyretics are given to relieve pain and fever.
The role of steroids is controversial. A study shows that a single dose of intravenous (IV) dexamethasone reduces the hospital stay and severity of symptoms.
These conservative measures can cure peritonsillitis; however, for peritonsillar abscess, drainage is a must along with medical management.
Aspiration with a wide-bore needle serves both diagnostic and therapeutic purposes. The aspirated pus can be sent for culture sensitivity, and in some cases, further incision and drainage may not be required.
Intraoral incision and drainage are carried out in a sitting position to prevent aspiration of pus. Oral and laryngeal mucosa is anesthetized with lidocaine 10% spray. The incision is given at the point of the maximum bulge above the upper pole of the tonsil. Another alternative site for incision is lateral to the point of junction of the anterior pillar with a line drawn through the base of the uvula. Quinsy forceps or No. 11 guarded blade and then sinus forceps are inserted to break the loculi. The opening created is left open to drain, and the patient is asked to gargle with sodium chloride solution. This helps in self-drainage of accumulated material.
In uncooperative, young patients or those affected in an unusual location, the procedure might have to be done under general anesthesia.
Rare complications of peritonsillar abscess include:
The prognosis in most patients is excellent. However, if there are airway compromise and delay in treatment, death can occur.
Peritonsillar abscess is usually managed by a team of healthcare professionals which include an ENT surgeon, primary care physician, emergency department physician, nurse, and pharmacist. Following treatment, followup is necessary to ensure recovery and the ability to consume an oral diet. The peritonsillar area must be examined at the clinic visit to ensure that there is no more abscess or reaccumulation of an abscess. In addition, the head and neck should be examined to ensure that the cervical adenopathy is resolving. Any patient with signs of recurrence should be referred back to the ENT surgeon for a formal tonsillectomy. (Level V)
The majority of patients with peritonsillar abscess who undergo prompt drainage and are treated with antibiotics recover within 4-7 days. About 1-5% of patients may develop a recurrent abscess and require a formal tonsillectomy. The risk of recurrence is highest in young people who have experienced five or more episodes of tonsillitis. After treatment, there is usually no residual sequelae. Complications like bleeding have been reported in less than 0.1% of patients. (Level V)