Case # 7: A Case of Asymmetry

A 22 year old male presents to the emergency department with a sore throat for 1 week. The pain is predominately on the left side and is associated with difficulty opening his mouth and fever. He was placed on amoxicillin 3 days ago but notes that his symptoms have progressed. He appears uncomfortable.

Vitals: T 101.4 HR 105 BP 132/81  RR 14 O2 98% on RA

A bedside ultrasound is performed, what is the next best step in management?


Answer and Learning Point


Incision and drainage. The patient presents with lateralizing pharyngitis symptoms associated with fever and trismus concerning for peritonsillar abscess (PTA). The ultrasound clip demonstrates a well circumscribed, hypoechoic fluid collection abutting the left tonsil confirming this diagnosis (see color overlay below).

Previously, physicians relied solely on the physical exam findings of peritonsillar swelling and uvular deviation to make the diagnosis of PTA. However, this approach lacks accuracy, with studies showing a sensitivity and specificity of 75% and 50% respectively [1]. This uncertainty leads to increased CT utilization, repeat drainage attempts and ENT consultation. Intraoral ultrasound is a novel technique that can be used by emergency physicians (EP), both for diagnosis and drainage of PTA. A recent randomized control trial found the use of intraoral ultrasound (vs. traditional landmark technique) to be significantly more reliable for differentiating between PTA and peritonsillar cellulitis. Additionally, this study also demonstrated increased success in PTA drainage by EPs with the use of intraoral ultrasound guidance [2].

Data from Costantino et al

Learning Points

    • An endocavitary probe should be used when PTA is suspected to differentiated between PTA and peritonsillar cellulitis; and assist with drainage if necessary.
    • If an endocavitary probe is not available, or if the patient cannot open their mouth wide enough to pass the probe, an alternative approach, known as the telescopic submandibular approach can also be used and is explained here.
    • When using ultrasound, the distance from the oral mucosa to the center of the PTA should be measure. The plastic sheath of an 18-gauge needle (preferably a spinal needle to allow the barrel of the syringe to be outside of the patients mouth) should be cut to this length to prevent puncturing any deeper structures during drainage.


This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.


    1. Scott PM, e. (2017). Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis. - PubMed - NCBI . Retrieved 2 October 2017, from
    2. Costantino TG, e. (2017). Randomized trial comparing intraoral ultrasound to landmark-based needle aspiration in patients with suspected peritonsillar abscess. - PubMed - NCBI . Retrieved 2 October 2017, from
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