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A peritonsillar abscess is the most common deep infection of the head and neck encountered in young adults in the Emergency Department.1 The incidence is approximately 45,000 cases per year.2 This infection can occur in all age groups, although it is a relatively rare before the age of 5 years. The highest incidence occurs in adults 20 to 40 years of age. There remains a fair amount of controversy in the literature regarding the optimal antibiotic choice and the mechanism of drainage. The objective for the Emergency Physician remains to make an accurate diagnosis, to institute appropriate care, and to arrange timely follow-up.

Knowledge of oropharynx anatomy is imperative. The anatomy of the oral cavity is relatively simple (Figure 175-1). The peritonsillar abscess can be found posterolateral to the palatine tonsil and posterior to the palatoglossal fold (or arch). Note the close proximity of the internal carotid artery and the facial artery to the peritonsillar abscess (Figure 175-2). Use extreme care to not penetrate too deeply and lacerate these arteries.

Figure 175-1.

Anatomy of the oropharynx as seen through the open mouth.

Figure 175-2.

Horizontal section through the mouth and oropharynx. Note the close proximity of the peritonsillar abscess to the internal carotid artery and the facial artery.

Most patients will have had symptoms for approximately 4 days by the time abscess formation has occurred. The most common symptoms include fever, sore throat, dysphagia, muffled voice (the “hot potato” voice), and trismus. Physical examination will reveal a nonexudative pharyngitis in the majority of cases, soft palate edema, a bulging prominent tonsil, and uveal deviation away from the abscessed tonsil (Figure 175-3). The differential diagnosis includes intratonsillar abscess, peritonsillar cellulitis, infectious mononucleosis, leukemias, odontogenic infections, and aneurysms of the internal carotid artery.

Figure 175-3.

A peritonsillar abscess. The abscess displaces the tonsil forward and medially. The uvula is deviated toward the contralateral side.

Intraoral ultrasound (US) for a peritonsillar abscess has been performed since the 1990s. It was first described in the Otolaryngology literature and subsequently in the Emergency Medicine literature. The first case series of patients whose peritonsillar abscesses were drained under US guidance was described by Blaivas and colleagues.3 Since that time, US guidance has been shown to have a high degree of sensitivity (85% to 92%) and specificity (80% to 100%).4,5 US offers the advantage of confirming the presence of an abscess prior to aspiration attempts as well allowing visualization of important neighboring structures (e.g., the internal carotid artery). Some patients with a peritonsillar abscess may be misdiagnosed with cellulitis and not undergo drainage. The use of US can prevent this. A significant proportion of ...

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