ACCURACY OF ULTRASOUND IN THE DIAGNOSIS OF ACUTE APPENDICITIS COMPARED WITH THE SURGEONS CLINICAL IMPRESSION

Objective: To compare the accuracy of the surgeon's clinical diagnosis of acute appendicitis with that of an ultrasonographic examination of the abdomen. Design: Prospective trial. Setting: US Naval Hospital, S an Diego, Calif. Patients: One hundred ten patients admitted to the ho spital with suspected appendicitis from May 1990 to June 1992. Interve ntion: Symptoms and signs for each patient were recorded, along with t he surgeon's clinical impression of immediate surgery or observation. The patient then underwent an ultrasound examination performed by a st aff radiologist. On the basis of the ultrasound findings the patient w as placed into one of three categories: appendicitis, normal examinati on results, or other conditions. Patients with an ultrasound-based dia gnosis of appendicitis proceeded to the operation, regardless of the s urgeon's clinical impression. Those with other conditions diagnosed wi th ultrasonography were treated as was appropriate for the condition. Results: The ultrasound-derived diagnosis of appendicitis had a sensit ivity of 85.5%, a specificity of 84.4%, a positive predictive value of 88.3%, a negative predictive value of 80.1%, and an overall accuracy of 85.0%. The surgeon's clinical impression at the time of admission h ad a sensitivity of 62.9%, a specificity of 82.2%, a positive predicti ve value of 82.9%, a negative predictive value of 61.7%, and an overal l accuracy of 71.2%. Conclusion: The overall accuracy of ultrasonograp hy in the diagnosis of appendicitis was statistically superior to that of the surgeon's clinical impression (P<.0001). However, 24% of the p atients with normal ultrasound findings were ultimately found to have appendicitis at operation, emphasizing the point that ultrasonography cannot be relied on to the exclusion of the surgeon's careful and repe ated evaluation.