UMEM Educational Pearls

Category: Visual Diagnosis

Title: What's the Diagnosis?

Posted: 10/25/2016 by Tu Carol Nguyen, DO (Updated: 10/26/2016)
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20 year-old female presents with sore throat, right throat fullness, difficulty speaking for 2-3 days. A bedside ultrasound and subsequent CT was obtained as seen below. What's the diagnosis?






Peritonsillar Abscess




The ultrasound image is a transcutaneous approach with a linear transducer that is placed at the angle of the mandible of the affected side. This is an alternative approach to an intra-oral ultrasound with the endocavitary transducer if the patient has trismus.

  • Peritonsillar abscess (PTA) is often taught as a clinical diagnosis; however, 36% are often peritonsillar cellulitis (PTC)
    • Sensitivity and specificity of clinical diagnosis of PTA are 78% and 50%, respectively
  • Classically, providers attempt blind needle aspirations (landmark-based)
    • Blind needle aspiration is unreliable for diagnosis of PTA with a false-negative rate of 10-24%
  • Intraoral sonography sensitivity: 90-100%
    • Using ultrasound can avoid unnecessary use of CTs and blind needle asprations


Take Home Points:

  • Consider intra-oral US for diagnosis of PTA vs. PTC and to reduce unecessary radiation with CT
  • Consider transcutaneous US to evaluate for PTA in the setting of trismus
  • Consider intra-oral US-guided needle aspiration of PTA vs. blind needle aspiration


How to do an intra-oral US-guided needle aspiration of PTA, check out:


For a brief video on how to perform a transcutaneous US for PTA:



Constantino TG, Satz WA, Dehnkamp W, Goett H. Randomized Trial Comparing Intraoral Ultrasound to Landmark-based Needle Aspiration in Patients with Suspected Peritonsillar Abscess. Academic Emergency Medicine. June 2012; Vol. 19 No. 6: 626-631.

Halm BM, Ng C, Larrabee YC. Diagnosis of a Peritonsillar Abscess by Transcutaneous Point-of-Care Ultrasound in the Pediatric Emergency Department. Pediatr Emerg Care. 2016;32(7):489-92.

Rehrer M, Mantuani D, Nagdev A. Identification of peritonsillar abscess by transcutaneous cervical ultrasound. Am J Emerg Med. 2013;31(1):267.e1-3.