Approach to the diagnosis and treatment of peritonsillar abscess in the emergency department

IV: intravenous; OR: operating room; PTA: peritonsillar abscess; US: ultrasound.

* There are no normative values for sizing of PTA on US. Patients with a small PTA are nontoxic, have minimal to no trismus; patients with a moderate to large PTA are more ill-appearing and have moderate to severe trismus. However, in our experience, trismus is associated with abscesses 1 to 2 cm or greater in diameter. Patients with equivocal findings or no abscess on US are presumed to have peritonsillar cellulitis in the appropriate clinical context. Refer to UpToDate topics for the differential diagnosis and clinical manifestations of PTA.

¶ For suggested antibiotic regimens, refer to UpToDate topics on peritonsillar abscess. Patients with peritonsillar cellulitis, small peritonsillar abscess not undergoing drainage, and patients with improvement after drainage of a peritonsillar abscess may be discharged home if they are well hydrated, have no airway compromise, and can tolerate oral intake including oral antibiotics. They should have ensured reevaluation within 24 to 36 hours. Otherwise, hospitalization is warranted. 

Δ Intraoral or submandibular US has significantly better sensitivity for distinguishing peritonsillar abscess from peritonsillar cellulitis than physical examination alone and improves the success of needle aspiration. Needle aspiration should be performed by a properly trained and experienced physician, typically an otolaryngologist. However, if US is not available, then patients who have a nontoxic appearance may undergo a trial of IV antibiotics and hospital observation instead of needle aspiration. Patients with a toxic appearance should receive treatment as for patients with moderate or large PTA by US.