Diagnosis of peritonsillar abscess: value of intraoral sonography.

Objective: Clinical differentiation of peritonsillar abscess from peritonsillar cellulitis can be difficult and often relies on blind needle aspiration of the tonsillar fossa to locate pus. The objective of this study was to establish a noninvasive and reliable sonographic technique for differentiating peritonsillar abscess from peritonsillar cellulitis in equivocal cases and to thereby avoid unnecessary needle aspiration.

Subjects And Methods: The study population included three healthy volunteers and 18 patients with clinically suspected peritonsillar abscess. The tonsils were assessed by using transcutaneous and intraoral sonography.

Results: The tonsils were visualized on both transcutaneous and intraoral sonograms in all three volunteers and in 16 patients. In one patient, the tonsils were not visualized on transcutaneous imaging; intraoral imaging showed cellulitis. In another patient, the intraoral examination was unsuccessful, whereas transcutaneous sonograms showed normal tonsils. On the basis of findings on transcutaneous sonograms, tonsils were considered normal in seven patients. Subsequent intraoral sonograms showed peritonsillar abscesses in four and peritonsillar cellulitis in two. Intraoral imaging was unsuccessful in one patient. On the basis of findings on transcutaneous sonograms, nine patients were thought to have peritonsillar cellulitis. Subsequent intraoral sonograms confirmed cellulitis in four and showed peritonsillar abscess in five. Transcutaneous sonography showed one peritonsillar abscess that was confirmed by findings on intraoral sonography. Surgical confirmation of sonographic findings was obtained in 12 of 18 patients; nine of 10 peritonsillar abscesses had surgical drainage, and three of seven cases of peritonsillar cellulitis had a dry, blind needle aspiration.

Conclusion: These results show that enlarged tonsils can be visualized with transcutaneous sonography, but intraoral sonography is necessary to adequately define the heterogeneous or cystic nature of a peritonsillar abscess. Intraoral sonography is a useful, simple, and well-tolerated noninvasive technique that can be used to accurately differentiate peritonsillar abscess from peritonsillar cellulitis in clinically equivocal cases. This technique eliminates the need for blind needle aspiration of the tonsillar fossa before surgical drainage. Intraoral sonography also can be used to monitor patients' responses after treatment.