Written by Chris Thom
Spoon Feed
In this retrospective study of 74 peritonsillar abscess (PTA) patients, there were no instances of inadvertent carotid puncture.
Big red can be easily avoided
This was a single-center retrospective study of 74 PTA patients aged 18 and older. The PTA was on the left side in 36, right side in 25, bilateral in 12, and indeterminate in one patient. The ED physician performed needle aspiration in 17, ENT in 14 cases. There were no procedural-related complications identified. Computed tomography (CT) scans were reviewed, and the distance from the posterior wall of the abscess to the anterior wall of the internal carotid artery (ICA) was measured. The median distance was 1.55 cm and the median abscess cavity was 2 cm in depth. This suggests the ICA should be at least 2.5 cm from the needle tip if a 1 to 1.5 cm exposed needle length is used. In addition, the ICA was almost always posterolateral to the abscess cavity.
How does this change my practice?
PTA drainage is rewarding and can result in immediate pain relief and improvement in oral intake tolerance. It is considered safe and within the scope of the practicing emergency physician, though the fear of “big red” is often discussed. To avoid carotid puncture, cut the plastic sheath of a 18 or 19 gauge needle, exposing 1 to 1.5 cm of needle, which should safely avoid the ICA. Also, avoid a posterolateral approach. POCUS is useful for PTA identification and allows direct visualization of the ICA and its depth prior to needle aspiration. Patients have improved outcomes when POCUS is used for PTA.
POCUS pro-tips and clips:
This might seem intimidating, but it tends to be well tolerated, with high-quality imaging. Atomize 5 to 10 mL of 1% lidocaine first and consider viscous lidocaine gargle, similar to what one might do for an NP scope. Use the endocavitary ultrasound probe with a sterile probe cover. Sterile gel can be applied but is not mandatory. Walk the probe back along the hard palate until you reach the posterior oropharynx and peritonsillar space. Sweep the probe from cephalad to caudal to visualize the space and any potential PTA. If present, a PTA will appear as a hypoechoic signal with internal echoes and complexity that are hallmarks of abscess. The ICA is the pulsatile structure posterior to the abscess, with color doppler often highlighting this anatomy well. See below.
Source
Risk of internal carotid injury during Peritonsillar abscess drainage in the emergency department. Am J Emerg Med. 2025 Apr 2;93:132-134. doi: 10.1016/j.ajem.2025.04.005. Epub ahead of print. PMID: 40199173
Increases efficiency of procedure and safety