Objective: To evaluate paranasal sinuses in patients with stable or acute asthma in order to determine the prevalence of acute bacterial rhinosinusitis. Methods: A cross-sectional study including 30 patients with acute asthma (73% females) treated in the emergency room and 30 patients with stable asthma (80% females) regularly monitored as outpatients. All patients completed a questionnaire on respiratory signs and symptoms and were submitted to ear, nose and throat (ENT) examination, as well as to X-ray and computed tomography (CT) imaging of the sinuses. Results: Based on the clinical diagnosis, the prevalence of acute bacterial rhinosinusitis was 40% in the patients with acute asthma and 3% in those with stable asthma. The ENT examination findings and the imaging findings in isolation were not useful to confirm the diagnosis. Conclusions: In themselves, ENT examination findings, X-ray findings and CT findings were not useful for the diagnosis of acute bacterial rhinosinusitis. Our results provide further evidence that a clinical diagnosis of bacterial rhinosinusitis should be made with caution.

Keywords: Asthma; Sinusitis; Radiography; Tomography, X-ray computed; Endoscopy.