Emergency department ultrasonography for the diagnosis of maxillary sinus fluid

Abstract

Study objectives: Diagnosis of sinusitis by history and physical examination alone is unreliable. Sinus computed tomography (CT) is the imaging modality of choice, but it is impractical in most cases. Presence of fluid in the sinus is the main CT finding in sinusitis, and maxillary sinus fluid can be seen with ultrasonography. We determine the sensitivity and specificity of emergency department (ED) sinus ultrasonography in the diagnosis of maxillary sinus fluid. Methods: This study took place in the ED and ICU of an urban, county medical center. A convenience sample of 48 patients with suspected maxillary sinusitis was prospectively enrolled. Sinus ultrasonography was performed with a 3.5-mHz microconvex probe, by attending or senior resident emergency physicians trained briefly in the technique of sinus ultrasonography. Sonographers were blinded to CT results. Partial or complete visualization of the posterior maxillary wall by sinus ultrasonography, indicative of fluid in the sinus, was considered to be a positive result. A limited sinus CT was obtained on the same day as sinus ultrasonography and read by an attending radiologist blinded to sinus ultrasonography results. Sinus CT showing partial or complete sinus opacification was considered positive. Defining sinus CT results as the criterion standard, sensitivity, and specificity of sinus ultrasonography were calculated. Results: Of 48 patients enrolled over a 17-month period, 40% were found to have sinusitis by CT. Sinus ultrasonography results were in agreement with CT in 86% cases. Compared with that of CT, the sensitivity of sinus ultrasonography was 81%, and the specificity was 89%, with a positive predictive value and negative predictive value of 78% and 91%, respectively. Conclusion: Sinus ultrasonography had a high sensitivity and specificity for maxillary sinusitis diagnosed by sinus CT. Sinus ultrasonography may be a useful adjunct to medical history and physical examination in the rapid bedside diagnosis of maxillary sinusitis.