What structure is most at risk for injury during the management of a peritonsillar abscess?

Structure Most at Risk During Peritonsillar Abscess Management

The internal carotid artery is the structure most at risk for injury during peritonsillar abscess drainage, though recent evidence suggests this risk is minimal when proper technique is employed.

Anatomical Considerations

The internal carotid artery lies posterior and lateral to the peritonsillar space, making it the most feared—albeit rare—complication during drainage procedures. 1, 2

Key Anatomical Measurements

• The mean distance between the peritonsillar abscess and the internal carotid artery is approximately 13.4 mm (range 5.3-19.1 mm), which is significantly closer than the contralateral side. 2
• The anterior border of the abscess typically lies 36.2 mm from the internal carotid artery. 2
• The angle between the abscess and the internal carotid artery averages 33.4 degrees, which is critical for understanding safe drainage trajectories. 2

Risk Stratification

• In a radiographic analysis of 34 patients, 82.4% were classified as low risk and 17.6% as moderate risk for internal carotid artery injury based on anatomical proximity. 2
• Despite theoretical concerns, actual injury to the internal carotid artery during peritonsillar abscess drainage is extremely rare when proper technique is used. 1

Safe Drainage Technique

The surgeon must pay meticulous attention to both the depth and angle of incision during abscess drainage to avoid vascular injury. 2

Technical Recommendations

• Limit needle or blade penetration depth to no more than 1 cm to minimize risk of deep structure injury. 2
• Direct the drainage instrument medially and anteriorly, avoiding posterior and lateral trajectories that approach the carotid artery. 2
• Consider ultrasound guidance, particularly in cases where anatomy is unclear or when the abscess-carotid distance may be reduced. 3, 4

Role of Imaging

• Transoral pharyngeal ultrasonography (TOPU) can delineate the anatomical relationship between the abscess and carotid artery before drainage, enhancing safety. 3, 4
• Point-of-care ultrasound in the emergency department can both diagnose peritonsillar abscess and facilitate safe drainage by visualizing vascular structures. 1
• CT imaging of the neck may be obtained when diagnosis is unclear, there is concern for deeper extension, or to rule out other pathologies, though it is not routinely required for straightforward cases. 1

Other Structures at Risk

While the internal carotid artery represents the most catastrophic potential complication, other structures in proximity include:

• Internal jugular vein: Located lateral to the carotid artery but generally at lower risk due to its more lateral position. 2
• Vagus nerve: Runs within the carotid sheath but injury is less commonly reported than vascular complications. 2
• The phrenic nerve is not anatomically relevant to peritonsillar abscess drainage as it courses through the neck at a much more anterior and lateral position.

Common Pitfalls to Avoid

• Excessive depth of penetration: The single most important factor in preventing carotid injury is limiting penetration depth to less than 1 cm. 2
• Incorrect angle of approach: Directing the needle or blade posterolaterally increases risk; always aim medially and anteriorly. 2
• Failure to use ultrasound when available: In cases with anatomical uncertainty or high-risk features, ultrasound guidance significantly enhances safety. 3, 4
• Inadequate visualization: Ensure proper lighting and patient positioning to clearly identify landmarks before proceeding. 5