Tests
1st tests to order
CBC
Test
Part of routine workup. Confirms neutrophilia.
Result
elevated WBC count, especially neutrophils
erythrocyte sedimentation rate
Test
Part of routine workup. Establishes degree of inflammatory disease in absence of significant neutrophilia.
Result
elevated
CT neck with contrast
Test
Definitive investigation.
Differentiates between phlegmon and confirms presence of abscess and aids in planning surgical approach. Air within or adjacent to a fluid collection or excessive free air between the neck fascial planes is highly predictive of an abscess.[20][27]
Result
ring-enhancing lesion in retropharyngeal space
x-ray of neck
Test
Lateral soft tissue x-ray of neck.
Ordered only if diagnosis is suspected and CT is not available, or diagnosis is less likely based on history and examination.[23]
Result
increased swelling of prevertebral space (>7 mm at C2 and >14 mm at C6)
ultrasonography of neck
Test
Quick and reliable investigation to differentiate between cervical lymphadenopathy or liquefaction within a group of matted lymph nodes in the neck. Can facilitate aspiration of small, uniloculated abscesses.
Result
lymphadenopathy; collection of fluid
examination under anesthetic (EUA)
Test
Should be performed if diagnosis is strongly suspected and the airway is compromised or if CT scanner is not available.
May also be performed if CT scan (or other imaging investigation) has been performed and the result is consistent with RPA. EUA confirms diagnosis and allows transoral incision and drainage with collection of pus for culture.
Result
bulging of posterior oropharyngeal wall
culture
Test
Pus collected from surgical drainage should be sent for culture and sensitivities.
Result
positive for infecting organism
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