Update your Knowledge with MKSAP 19 Q&A: Answer and Critique


A: CT of the sinuses

Educational Objective

Evaluate a patient with suspected chronic sinusitis.


The most appropriate diagnostic test to perform next is CT of the sinuses (Option A). Chronic sinusitis manifests with at least 12 weeks of nasal congestion with purulent drainage, diminished sense of smell, or facial pain/pressure. It may be associated with nasal polyposis (with a strong association with asthma). Demonstration of mucosal involvement by nasal endoscopy or imaging (typically CT) is necessary for diagnosis. The findings most commonly seen on CT scan include mucosal thickening, sinus ostial obstruction, polyps, and sinus opacification. Treatment includes glucocorticoids and antibiotics. CT without contrast is the most commonly used imaging modality for the diagnosis of chronic sinusitis.

Although mucosal disease can be demonstrated with MRI (Option B), CT has higher resolution and better diagnostic accuracy for mucosal disease and sinus ostial occlusion. In addition, MRI is more costly than CT and does not provide a more accurate diagnosis. MRI should be considered when there is suspicion for infection or inflammation that extends beyond the sinus cavities.

The possibility of infection with unusual or resistant organisms is suggested by the persistence of symptoms despite previous antibiotic therapy. In this case, it is important to obtain bacterial and/or fungal cultures directly from the sinus via nasal endoscopy or by sinus puncture. Nasal swabs (Option C) are inadequate because they do not accurately predict the infecting organism and cannot be used to guide therapy. This patient has no indication for bacterial and/or fungal culture at this time. Findings on CT may suggest the need for more aggressive evaluation.

Plain radiography of the sinuses (Option D) may show changes suggestive of chronic sinusitis, including sinus opacification and mucosal thickening. These findings, however, are nonspecific. Furthermore, plain radiography lacks sufficient sensitivity to determine the presence or extent of potential bony erosion by infection.

Key Points

Patients with chronic sinusitis, characterized by nasal congestion, purulent rhinorrhea, and headache for more than 12 weeks, should undergo either nasal endoscopy or CT of the sinuses for diagnostic purposes.

In patients with chronic sinusitis, the findings most commonly seen on CT include mucosal thickening, sinus ostial obstruction, polyps, and sinus opacification.


Kwah JH, Peters AT. Nasal polyps and rhinosinusitis. Allergy Asthma Proc. 2019;40:380-4. [PMID: 31690375] doi:10.2500/aap.2019.40.4252

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