Ryan Erwin, MS4
The Article: Costantino, et al. “Randomized Trial Comparing Intraoral Ultrasound to Landmark-based Needle Aspiration in Patients with Suspected Peritonsillar Abscess.” Academic Emergency Medicine 2012 19:6
The Idea: Peritonsillar abscess (PTA) is a relatively common infection presenting to the emergency department, with an incidence of about 1 in 10,000. Diagnosis is often made based on physical findings, such as peritonsillar swelling and uvular deviation. However, studies have shown physical examination to have only around 75% sensitivity and 50% specificity. This ambiguity can lead to unnecessary imaging and ENT consultation. To remedy this, clinicians have begun to use intraoral ultrasound (US) to improve diagnostic accuracy. The goal of this study was to compare the diagnostic accuracy for detecting PTA or peritonsillar cellulitis (PTC) using either intraoral US or initial needle aspiration after visual inspection (the landmark technique [LM]).
The Study: This was a prospective, randomized, controlled clinical trial using a convenience sample of adult patients who presented to a single, large, urban university hospital between October 2008 and December 2010.
Inclusion criteria: Age >18 years, able to give consent, and presenting with constellation of signs and symptoms that, in the judgment of the treating attending physician, represented a PTA, and that physician was ready to perform a needle aspiration of the PTA.
Exclusion criteria: Clinical instability due to airway or hemodynamic compromise
All patients were enrolled by an attending physician credentialed for US-guided procedures. Procedures were performed by either a second- or third-year EM resident under the supervision of the attending physician. Patients in the LM arm had needle aspiration attempted according to an established protocol. Patients in the US arm underwent intraoral US, where abscess and carotid artery were identified. The probe was withdrawn and needle aspiration was attempted (unless no abscess was identified). A maximum of three aspiration attempts were made in each arm, then clinical care proceeded at the discretion of the attending physician. All patients were instructed to follow up in the ED in 2 calendar days.
Primary Endpoint: Successful diagnosis
Secondary Endpoint: Successful aspiration of purulent material from patients with PTA, frequency of CT scanning, and ENT consultation
Results: A total of 28 patients were enrolled, with 14 in each arm. There were 8 PTA and 6 PTC in the US arm, and 10 PTA and 6 PTC in the LM arm. The diagnostic accuracy for US was 100% versus 64% for LM (p=0.04). US led to more successful aspiration of purulent material then LM in patients with PTA (100% vs 50%, p=0.04). ENT consult rate in US was 7% vs 50% in LM (p=0.04). CT was not used on any patients in the US arm, compared to 35% in LM arm (p=0.04). One patient in each arm had evidence of increased PTA on follow-up 2 days later, requiring further drainage. No other delayed complications or recurrence were identified.
Take-Away: The results of this study suggest that intraoral US can be used to distinguish between PTA and PTC and guide abscess drainage, as well as decrease the usage of CT and ENT consults. A potential limitation of this study was the convenience sampling, as the treating clinicians may have been more inclined to attempt US visualization when the study authors were present. Additionally, the treating clinicians were all experienced with performing US scans, which may limit generalizability to practicing physicians.