Today’s post is inspired by real-life events and comes with a video (consent given by the patient and providers).

The case:

29M presents with dysphonia, odynophagia, and drooling.

He is hypertensive, with a low-grade fever, but he is maintaining his airway and has a good respiratory rate/o2 saturation. Examination of the posterior oropharynx shows a uvula deviated to the right, and fullness of the left peritonsillar area.

You think you have your diagnosis, but this could be just really bad cellulitis.  You want to be sure, so you grab an ultrasound. First question, do you have to use the endocavitary probe? and second, does this even matter?

We’ll skip the first question for now and head to the second part…It definitely matters. The development from tonsillar cellulitis to frank abscess can be difficult to differentiate because they have overlapping clinical presentations, as both may have similar signs and symptoms. The ability of clinicians to reliably differentiate PTA from peritonsillar cellulitis by physical examination alone is limited. In one study of ENT providers, the physical exam was 78% sensitive, 50% specific for diagnosing PTAs. When using endocavitary ultrasound, the sensitivity approaches 95%.

The endocavitary probe is thus undeniably better than physical exam for diagnosis, and possibly better than CT (specifically in pediatric populations). It also increases the chance for successful I&D when compared to using a landmark approach. It can, however, be unwieldy, uncomfortable, and near impossible for a patient with really bad trismus (not uncommon in PTA.) If only there was an ultrasound approach to evaluate and treat PTAs that didn’t require sticking a probe into the mouth…I’m sure you see where this is going.

In comes the submandibular or transcutaneous ultrasound for evaluation of PTA. The first paper detailing the use of transcutaneous ultrasound for PTA by EPs was published in 2012. It consists of a single case and describes how transcutaneous ultrasound can be an effective backup to intraoral ultrasound in a pinch.  Here’s how to do it.

  1. Place a high-frequency linear transducer (or abdominal probe for a wider field) under the mandible with the probe marker facing the right of the patient.
  2. Evaluate the unaffected side to identify the normal tonsillar tissue and then proceed to the affected side.
  3. Locate the internal jugular vein and carotid artery and then fanning cephalad until the pharyngeal tonsil is located.
  4. The probe should be moved laterally after identifying the pharyngeal tonsil. If a heterogeneous structure suspicious for an abscess is identified adjacent to the tonsil, place color flow on the structure to differentiate it from vascular structures or hyperemic tonsillar tissue. The heterogeneous structure is most likely an abscess if no flow is seen compared with tonsillar tissue or vascular structures that will demonstrate color enhancement.
  5. If an abscess is not identified, Use the intraoral technique if the patient will tolerate it.

For the statistician in all of us, it bears mentioning that transcutaneous is less sensitive than intraoral ultrasound for the diagnosis of PTAs (at least in Brazilian radiologist it is), but transcutaneous is more specific. When a patient has trismus, the sensitivity of transcutaneous ultrasound is higher since patients with trismus generally have larger collections. These exams (intraoral vs. transcutaneous) showed similar accuracy.  So if a patient presents with a possible PTA and trismus, don’t fret. Just use a transcutaneous probe instead.

If all goes well, you’ll have a syringe filled with sanguinopurulent fluid in no time.

Just ask these guys…


  1. Scott, P.M., Loftus, W.K., Kew, J., Ahuja, A., Yue, V., and van Hasselt, C.A. Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis. J Laryngol Otol1999113229
  2. Costantino, T. G., Satz, W. A., Dehnkamp, W. and Goett, H. (2012), Randomized Trial Comparing Intraoral Ultrasound to Landmark‐based Needle Aspiration in Patients with Suspected Peritonsillar Abscess. Academic Emergency Medicine, 19: 626-631. doi:10.1111/j.1553-2712.2012.01380.x
  3. Rehrer, Matthew et al. Identification of peritonsillar abscess by transcutaneous cervical ultrasound. The American Journal of Emergency Medicine , Volume 31 , Issue 1 , 267.e1 – 267.e3

  4. Filho, B et al. Intraoral and transcutaneous cervical ultrasound in the differential diagnosis of peritonsillar cellulitis and abscesses,Brazilian Journal of Otorhinolaryngology,Volume 72, Issue 3, 2006, 377-381, doi:10.1016/S1808-8694(15)30972-1.