Topic Editor: Becky Box, MBBS
Review Date: 10/16/2012
Definition 
A Peritonsillar Abscess (PTA) is a collection of pus in the peritonsillar tissue, which is the space between the palatine tonsil and its capsule. PTA usually forms as a result of acute tonsillitis or peritonsillar cellulitis. In some cases it can occur in the absence of preceding infection, or as a result of infected Weber's glands (mucous glands on posterior border of the tongue and superior pole of the tonsil).
Description
- PTA is one of the most common deep tissue infections of the head and neck. The typical presentation is sore throat, trismus, muffed voice, severe pain, dysphagia, and sometimes dehydration
- Anatomically, the peritonsillar tissue is between the capsule surrounding the palatine tonsils and the lateral wall of the oropharynx. The palatine tonsils lie in the depression between the palatoglossal and palatopharyngeal arches, which form the two tonsillar pillars (formed by the glossopalatine & pharyngopalatine muscles)
- Peritonsillar abscess is typically a polymicrobial infection involving gram positive cocci & anaerobic organisms
- Treatment of superior pole peritonsillar abscess usually requires repeated aspiration or simple incisional drainage of pus and management with antibiotics for residual infection.
- Inferior pole peritonsillar abscess is rare, and is easily missed due to its anatomic location. This condition usually requires definitive surgical management due to technical difficulties in aspirating this location
- The appropriate and prompt management of peritonsillar abscess is necessary to avoid the development of life-threatening complications including extension of infection into retropharyngeal and parapharygeal spaces. Such extension can lead to airway obstruction, posterior mediastinitis, or septic necrosis with carotid sheath hemorrhage
Epidemiology
Incidence/Prevalence
- Incidence of PTA in United States is 30/100,000 person-years representing about 45,000 new cases per year
- A Scandinavian study reports similar incidence with a range between 19-37/100,000 person-years
Age
- Adults between 20-40 years of age have the highest incidence of PTA
- PTA can occur in all age groups
Gender
- Genders are equally affected
Risk factors
- Age (young adults)
- Periodontal caries may increase risk, but further studies are required to confirm this as an independent risk factor
- Prior episodes of tonsillitis
- Smoking
Etiology
- The etiology of PTA has come under scrutiny in several recent review articles. Traditionally PTA was felt to result from progression of acute exudative tonsillitis with extension into the peritonsillar tissues leading to a discrete abscess. Contrary to this, some PTAs occur spontaneously without a preceding sore throat. Other cases demonstrate abscess despite minimal time from onset of sore throat. There may be alternate etiologies in such patients
- One commonly accepted theory for the development of PTA includes obstruction of Weber's glands (small salivary glands at the posterior aspect of the tongue and superior pole of the tonsil)
- The most common aerobic organisms associated with PTA are Streptococcus pyogenes, Staphylococcus aureus, Haemophilus influenza, Neisseria species,and Pneumococci. Anaerobic organisms include Fusobacterium, Peptostreptococcus, Prevotella and Bacteroides
[Outline]
History
- PTA may present with a history of acute pharyngitis accompanied by tonsillitis and worsening of unilateral pharyngeal discomfort
- The median duration of symptom onset to time of presentation is 3-5 days
- Constitutional symptoms at the time of presentation may include malaise and fever
- Disease specific symptoms include:
- Sore throat (more severe on affected side)
- Dysphagia (sometimes as severe to limit the ability to swallow saliva)
- Otalgia
- Headache
Physical findings on examination
- Patients commonly present with trismus due to pain from inflammation and spasm of masticator muscles
- Pooling or drooling of saliva may be present due to swallowing difficulty
- Patients often speak in a muffled voice known as 'hot potato voice'
- Patients may have associated rancid breath
- Palpable tender cervical lymphadenitis may be present on the affected side
- Oropharyngeal examination should reveal an erythematous swollen anterior tonsillar pillar, usually with erythema extending to the soft palate. The affected tonsil is generally displaced inferiorly and medially with contralateral deviation of the uvula
[Outline]
It is important to note that experienced clinicians can manage and diagnose many PTA cases with no laboratory testing or imaging. In certain cases, cultures, blood testing, and/or radiographic evaluation is valuable, even essential.
Blood test findings
PTA can be diagnosed on clinical history and physical findings alone. The presence of pus on needle aspiration or radiologic imaging showing fluid collection can be helpful in differentiating PTA from peritonsillar cellulitis
- Blood testing adds very little value, except in cases of a septic or bacteremic appearing patient
- Some practitioners obtain a full blood count, and more rarely a CRP (adds little to no value over experienced clinical evaluation)
- Basic metabolic panel (electrolytes, urea and creatinine) can be obtained in dehydrated patients; but is also adds little value to the clinical evaluation
- Monospot test [to detect infectious mononucleosis (IM)]: IM is on the differential diagnosis for PTA as it is present a co-infection in 1.4 -5% of cases. Monospot test should be considered in patients with a history and examination consistent with IM i.e. lethargy, myalgia, hepato/splenomegaly or bilateral cervical lymphadenopathy
- If IM is present, liver function tests may be indicated
Other laboratory test findings
- Throat culture: The utility of throat culture in management is debatable. Culture and gram stain of abscess aspirate is recommended by many experts, with the goal of providing aid in selection of appropriate antibiotics
- A 2008 study suggests that due to the time required for return of culture results, follow-up and modification of therapy is rare (except admitted patients). It has also been shown that the results of such cultures rarely alters antibiotic therapy, as most patients are already improving by the time of return of such results
- Some studies indicate that the utilization of gram stain alone may be sufficient to indicate antibiotic choice, and culture could be abandoned in most cases
Radiographic findings
- Transcutaneous or intraoral ultrasonography: Can be helpful in identifying an abscess and in distinguishing PTA from peritonsillar cellulitis. Trismus can limit the ability to perform this examination
- Computed tomography (CT) scan or magnetic resonance imaging (MRI):
- CT (with IV contrast) is only indicated in cases where there is clinical suspicion of spread of infection beyond the peritonsillar space or concern of a complication in the lateral neck space including erosion into the carotid sheath or jugular venous thrombosis
- MRI gives greater soft tissue definition and is more effective in detecting complications, however it has limited availability and is more expensive and time consuming. CT is usually the first line investigation in such cases
Other diagnostic test findings
- Needle aspiration is the gold standard for the diagnosis of PTA. It is obtained by aspirating pus from the abscess through a large bore needle. Although not a complex procedure, appropriate training is essential, especially given the proximity to the carotid artery. This aspirate can be sent for laboratory testing, such as gram stain +/- culture
[Outline]
General treatment items
- The mainstay of treatment for PTA includes drainage of the abscess, antibiotics, analgesics/antipyretics, and maintenance of hydration
- Cases where dehydration is present require intravenous fluids until the patient is again capable of resuming adequate oral fluid intake
- Analgesia should be titrated to control the patient's pain. It is common to require a combination acetaminophen, NSAID and often parenteral opioids
- Use of steroids is common, but is not fully proven. One study showed statistically significant improvement in pain relief with a single IV dose of methylprednisone
- Drainage of the Abscess
- The procedure options for drainage of PTA are needle aspiration, incision and drainage, or immediate tonsillectomy. Drainage using any of these methods, along with antibiotic treatment results in resolution of PTA in >90% of cases
- There is limited evidence as to the efficacy of incision and drainage over needle aspiration. Current research suggests that needle aspiration is the preferred patient choice
- Needle aspiration has advantages as it can be done in the emergency department setting and does not require an otolaryngologist or surgeon
- Aspiration can be performed with the patient being managed as an outpatient
- I&D usually requires a trained surgeon and is more likely to require an overnight stay for observation of the airway and hemorrhagic complications
- One study indicates that I&D is more painful during the procedure, but has the benefit of more rapid resolution of pain and time of recovery to swallow
- Whether aspiration or I&D is performed, the rate of recurrence is similar, at 10%
- Immediate tonsillectomy is generally not required for treatment of PTA
- 1998 Pediatric guidelines indicate that needle aspiration is the treatment of choice in pediatric patients without recurrent tonsillitis. Patients with recurrent tonsillitis and PTA (~ 20%) should be considered for abscess tonsillectomy. These guidelines indicate a 95% tolerance rate for aspiration in patients given appropriate analgesia/sedation
- Tonsillectomy should be performed 3-6 months after abscess resolution in patients with recurrent tonsillitis or PTA. There is no evidence for Interval tonsillectomy in other patients
- Antibiotic Choice
- Antibiotic selection is initially empiric, but can later be modified based upon gram stain and/or culture of aspirated abscess fluid
- Penicillin had formerly been the choice for the treatment of PTA, although emergence of beta-lactamase-producing organisms may require consideration of other options. A common approach includes choosing one of the following:
- Cephalexin
- Cefuroxime
- Cefpodoxime
- Other cephalosporin
- AND either adding metronidazole or not to this
- Other options include clindamycin or amoxicillin/clavulanate (if infectious mononucleosis has been ruled out)
- Oral antibiotics should be initiated when oral intake is tolerated. The duration of treatment should be 7-10 days modified in length depending upon clinical response
- An alternative approach to antibiotic choice, is basing decisions on the gram stain result, without obtaining a culture. Patients with gram stains that show only gram positive cocci have a high probability of penicillin susceptibility and should be managed empirically with penicillin. Patients with gram negative rods will have a greater incidence of beta-lactamase resistance and should be given a broader spectrum cover including anaerobe cover
- When implementing a non-culture approach, consideration of high risk patients, such as those who are immunocompromised, have recurrent infections, or are otherwise are at higher risk of resistant organisms, should usually have broader antibiotic cover and may be more likely to benefit from abscess fluid culture
Medications indicated with specific doses
Antibiotics
- Amoxicillin/clavulanate
- Cefpodoxime
- Cefuroxime [Oral]
- Cephalexin
- Clindamycin [Oral]
- Metronidazole [Oral]
- Penicillin V potassium
- Penicillin G benzathine [IM]
Dietary or Activity restrictions
- No restrictions; however, following abscess drainage, a liquid diet is recommended until solids are tolerated
Disposition
Admission Criteria
- Airway compromise
- Altered mental status
- Dehydration and inadequate oral intake
- Extension of infection beyond PTA (e.g., deep space neck infections)
- Sepsis
Discharge Criteria
- Most patients with PTA can be discharged home on oral antibiotics after abscess drainage
- Must be able to tolerate sufficient oral intake and antibiotics
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