Comparison of graded compression ultrasonography and unenhanced spiral computed tomography in the diagnosis of acute appendicitis.

INTRODUCTION To compare the accuracy of graded compression ultrasonography (US) and unenhanced spiral computed tomography (CT) in the diagnosis of acute appendicitis. METHODS This prospective study comprised 58 consecutive patients with high clinical suspicion of acute appendicitis. After careful clinical assessment and laboratory investigations, all the patients were independently evaluated by graded compression US followed by unenhanced spiral CT, in order to establish the diagnosis. CT was performed from the level of the third lumbar vertebral body to the pubic symphysis, and no patient was given oral, rectal or intravenous contrast agents. The results were compared with operative findings and clinical follow-up. RESULTS Out of the 58 patients evaluated, surgical confirmation was obtained in 52 patients and the remaining six patients were managed conservatively. Statistical analysis was based on the 52 patients who were surgically confirmed. 48 of the operated patients had evidence of appendicitis and four patients had negative findings. In our study, 90 percent of patients were adults and the following results were more applicable to the adult age group. Analysis of the data for US and CT, respectively, revealed a sensitivity of 67.3 percent versus 95.8 percent, specificity of 100 percent versus 75 percent, accuracy of 71.2 percent versus 90.3 percent, positive predictive value of 100 percent versus 97.8 percent, and negative predictive value of 15.8 percent versus 60 percent. Out of the operated patients, four patients did not have acute appendicitis and alternative diagnosis was suggested by US and CT in one patient. Of the six patients managed conservatively, an alternative diagnosis was reached both by US and CT in two patients. CONCLUSION We conclude that unenhanced spiral CT is more sensitive than US in detecting appendicitis, especially in adult patients.