What is the best imaging study to evaluate an abscess under the tongue?

Imaging for Sublingual Abscess

CT with IV contrast is the imaging modality of choice to evaluate an abscess under the tongue (sublingual abscess). 1, 2

Primary Imaging Recommendation

Obtain a CT scan with intravenous contrast for suspected sublingual or lingual abscess. 1, 2 This provides:

• Rapid acquisition and high availability in emergency settings where airway compromise is a concern 1
• Precise anatomical localization of the abscess collection, critical for determining whether the abscess is anterior (more common) versus posterior tongue, which dictates different surgical approaches 1, 2
• Assessment of abscess extent and relationship to surrounding structures, including potential spread to deep neck spaces 1
• Guidance for surgical planning or needle aspiration approach 2

Clinical Context and Urgency

Sublingual abscesses are rare but potentially life-threatening due to risk of acute airway compromise. 3, 1, 4 Key clinical features to recognize include:

• Severe tongue pain and swelling (typically anterolateral location) 3
• Dysphagia, drooling, and difficulty opening the mouth 3
• Progressive dyspnea indicating impending airway obstruction 1
• Fever and systemic signs of infection 3, 4

Imaging is essential because clinical examination alone can be difficult, particularly for posterior tongue abscesses which are harder to visualize on physical exam. 1

Why CT Over Other Modalities

While the ACR Appropriateness Criteria do not specifically address tongue abscesses, extrapolating from guidelines on soft tissue infections and intra-abdominal abscesses:

• CT with IV contrast has superior accuracy (85-95% sensitivity and specificity) for detecting and characterizing abscesses compared to ultrasound or clinical examination alone 5
• IV contrast enhancement helps distinguish abscess walls from surrounding edematous tissue and identifies complications 5
• MRI, while highly accurate for soft tissue infections (86-100% sensitivity for abscesses), requires longer acquisition time and may not be immediately available in emergency settings 5, 6

MRI as Alternative

MRI without and with IV contrast is an excellent alternative if CT is contraindicated or for complex cases requiring detailed soft tissue characterization. 6 The ACR notes MRI provides:

• Superior spatial and contrast resolution for soft tissue infections 6
• Excellent definition of anatomical relationships for surgical planning 6
• Avoidance of radiation exposure 6

However, MRI is typically not the first-line study due to longer scan times and limited availability when urgent airway management may be needed. 5, 6

Ultrasound Limitations

Ultrasound is not recommended for sublingual abscess evaluation because:

• It has limited ability to visualize deep tongue structures 6
• Operator-dependent technique may miss collections 5
• Tongue pain and swelling make adequate probe contact difficult 5

Critical Pitfalls to Avoid

• Do not delay imaging in patients with progressive tongue swelling and dyspnea—airway compromise can develop rapidly 1
• Differentiate anterior from posterior tongue abscesses on imaging, as posterior abscesses are more likely to cause airway obstruction and require different surgical approaches 1, 2
• Consider immunocompromised status (diabetes, immunosuppressive medications) as a risk factor for spontaneous lingual abscess even without trauma history 7
• Ensure anesthesia/airway management team is available before any intervention, as manipulation can precipitate acute obstruction 1