Deep Neck Infections Workup

Updated: Apr 07, 2022
  • Author: Alan D Murray, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Laboratory Studies

See the list below:

  • A high index of suspicion is important when diagnosing a deep neck space infection. A careful history and physical examination (see Clinical) are critical to the workup. In addition, tests, including the following, may be useful in the workup of a patient in whom a deep neck space infection is suspected:

    • Blood chemistries

    • Complete blood cell count

    • Clotting profile (particularly important in patients who require surgical drainage)

    • Blood cultures (may be indicated in septic patients)

    • Abscess cultures with Gram stains (critical to direct antimicrobial therapy)


Imaging Studies

See the list below:

  • Lateral neck radiography

    • These tests may reveal soft tissue swelling in the prevertebral region. Lateral neck radiographs can also demonstrate radiopaque foreign bodies, subcutaneous air, air fluid levels, and erosion of the vertebral bodies.

    • Prevertebral soft tissue thickening greater than 7 mm over C2 or greater than 14 mm in children and 22 mm in adults over C6 is highly suggestive of a retropharyngeal process.

  • Mandible series

    • When a dental source of the infection is suggested, a Panorex can help evaluate the patient for a dental abscess.

    • Particular attention should be given to the second and third mandibular molars because the apices of these teeth extend below the mylohyoid line, giving them access to the submandibular space.

  • Chest radiography: To evaluate the mediastinum, check for subcutaneous air or pneumomediastinum, displacement of the air stripe, or concurrent pneumonia suggesting aspiration.

  • CT scanning

    • CT scans with contrast are the gold standard in evaluation of deep neck infections. The importance of CT scanning is highlighted in a study by Crespo et al, who found that clinical examination alone underestimated the extent of deep neck space infections in 70% of patients. CT scans indicate the location, boundaries, and relation of infection to surrounding neurovascular structures. Abscesses are seen as low-density lesions with rim enhancement, occasional air fluid levels, and loculations (see the images below). A study by Kirse and Roberson also notes the association between irregularity of the abscess wall on CT as predictive of pus within the cavity. [22] CT scans are fast, relatively inexpensive, and fairly widely available today. CT scanning of the chest may be helpful if extension into the mediastinum is suspected.

      CT scan of the neck demonstrating left peritonsill CT scan of the neck demonstrating left peritonsillar abscess.
      Right lateral pharyngeal (parapharyngeal) abscess Right lateral pharyngeal (parapharyngeal) abscess as seen on CT scan. Note the medial extension in the retropharyngeal area.
      Same patient as in the previous image. Lower cut C Same patient as in the previous image. Lower cut CT scan showing the abscess cavity. The rim enhancement and partial loculation are well demonstrated.
    • A prospective, blinded study of the effectiveness of CT scanning in diagnosing deep neck infections in adults over the age of 18 showed that CT scan with contrast is 95% sensitive and 53% specific for distinguishing a drainable fluid collection. When CT findings were combined with clinical exam findings, the sensitivity remained about 95%, but the specificity increased to about 80%. The data regarding the utility of CT scans in diagnosing deep neck infections in children are not as clear as in adults.

  • MRI: Because of the increased time and expense involved in obtaining an MRI result, MRI is not the initial modality of choice. However, when obtained, MRI scans can give excellent soft tissue resolution to help localize the region of involvement.

  • Ultrasound: Ultrasounds do not reveal anatomic details but can help distinguish between phlegmon and abscess, give information about the condition of surrounding vessels, and guide fine-needle aspiration (FNA) attempts.

  • Arteriography: This may be helpful when carotid, jugular, or innominate involvement is suggested.