Assessment of Effectiveness of Ultrasonography in Diagnosis of Acute Appendicitis: Correlation with Level of Initial Clinical Diagnostic Confidence.

Abstract

PURPOSE: To evaluate effectiveness of ultrasonography (US) in the diagnosis of acute appendicitis by comparing with initial level of clinical diagnostic confidence. MATERIALS AND METHODS: Graded compression US of one hundred forty eight with clinically suspected of acute appendicitis were prospectively evaluated. General surgeons classified patients into three groups based on the clinical probability before US examination: group 1 as cases with low probability (<25%), group 2 as cases with an intermediate probability (25-75%) and group 3 as cases with a high probability (>75%). Two radiologists performed US examination. Statistical significance of ultrasonographic results in each group was assessed. RESULTS: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of sonography for all patients were 91.3%, 97%, 97.3%, 90.4%, and 93.9% respectively. Those of group 1 were 100%, 95.5%, 84.6%, 100%, and 96.4%, and those of group 2, 95.8%, 100%, 100%, 95%, and 97.7% while those of group 3, 86.4%, 100%, 100%, 50%, and 88%. There was no statistical difference in each parameter among three groups. The accuracy and NPV in group 3 was significantly higher than those in groups with the low and intermediate probability (group 1 and 2). CONCLUSION: Ultrasonography in the diagnosis of acute appendicitis is an useful and reliable method, especially in case of low clinical diagnostic confidence.