The use of ultrasound imaging in evaluation of peritonsillar infections.

OBJECTIVES/HYPOTHESIS The objectives of this study were to evaluate safety and patient tolerance of intraoral ultrasound and to evaluate efficacy of intraoral ultrasound in the diagnosis of peritonsillar infections. STUDY DESIGN Prospective single-cohort study involving adult patients (age>18 years) with evaluation consistent with possible peritonsillar abscess. METHODS Twenty-four patients were evaluated in the emergency department for peritonsillar infection. Signs and symptoms were recorded including uvular deviation, trismus, and fluctuance. Intraoral ultrasound was performed, and presence or absence of abscess was recorded. Eight patients had a computed tomography (CT) scan. Needle aspiration was performed by the otolaryngology physician in appropriate patients. Presence of purulence confirmed peritonsillar abscess. RESULTS Intraoral ultrasound was successfully performed on 87.5% (21/24) of patients. The probe could not access the peritonsillar space in 12.5% (3/24) of patients due to trismus. The positive predictive value of ultrasound in diagnosing abscess was 78.6% (11/14). The negative predictive value was 100% (7/7). The specificity was 70% (7/10), and the sensitivity was 100% (11/11). CT scan of the neck was obtained in 8/24 patients and found to be 100% sensitive and specific in diagnosing abscess. CONCLUSIONS Intraoral ultrasound is a sensitive imaging modality at our institution, making it a strong initial imaging choice in patients with peritonsillar infections. Ultrasound can reliably rule out the presence of abscess and make CT of the neck unnecessary in most patients. Although ultrasound is generally well tolerated, diagnosis in patients with severe trismus can be made clinically or with CT scan. Intraoral ultrasound is a useful tool in diagnosing and treating peritonsillar infections when imaging is required. LEVEL OF EVIDENCE 4.