Medical Treatment for Acute Sinusitis Workup

Updated: Mar 31, 2022
  • Author: Ted L Tewfik, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Laboratory Studies

Some authors have reported on the use of laboratory tests including sedimentation rate, white blood cell counts, and C-reactive protein levels to help diagnose acute sinusitis. [4] These tests appear to add little to the predictive value of clinical findings in the diagnosis.

Cultures are not routinely obtained in the evaluation of acute sinusitis but should be obtained in a patient in intensive care or with immunocompromise, in children not responding to appropriate medical management, and in patients with complications of sinusitis. Because the nose is colonized with multiple nonpathogenic species of bacteria, care must be taken when evaluating culture results. A specific organism is considered pathogenic when more than 104 colony-forming units of the species are grown on culture or when polymorph counts are greater than 5000 cells/mL.


Imaging Studies

Imaging studies are not necessary when the probability of sinusitis is either high or low but may be useful when the diagnosis is in doubt, based upon a thorough history and physical examination. Plain sinus radiographs may demonstrate mucosal thickening, air-fluid levels, and sinus opacification. Limitations of plain films include interobserver variability, inability to distinguish infection from a polyp or tumor disease, and poor depiction of the ethmoid and sphenoid sinuses.

CT scanning has poor specificity for the diagnosis of acute sinusitis, demonstrating sinus air-fluid levels in 87% of individuals with simple URTIs and 40% of asymptomatic individuals. CT scanning is the modality of choice, however, in specific circumstances such as in the evaluation of a patient in intensive care, when complications are suspected, or in the preoperative evaluation of surgical candidates. CT scanning can give valuable information regarding the anatomical and mechanical contributions in the development of acute sinusitis. Coronal views with bone windows are the preferred sinus study for evaluating each of the sinuses as well as the ostiomeatal complex.

Magnetic resonance imaging (MRI) is excellent for evaluating soft tissue disease within the sinuses, but it is of little value in the diagnostic workup for acute sinusitis.