A prospective trial of computed tomography and ultrasonography for diagnosing appendicitis in the atypical patient

BACKGROUND: The surgical diagnosis of acute appendicitis is customarily mad e on clinical grounds alone using history, physical examination, and white blood cell count. In the atypical patient, ie, the patient with prolonged s ymptoms, inconsistent history, or misleading physical examination, diagnost ic studies should be helpful in establishing the appropriate diagnosis. Com puted tomography (CT) scan and ultrasonography (US) have demonstrated utili ty in diagnosing appendicitis but have not been studied in the atypical pat ient population. METHODS: A retrospective review of 500 consecutive appendectomy patients, c oupled with a review of the literature, resulted in the development of an a lgorithm to help the medical physician to differentiate the atypical patien t requiring an imaging study from those requiring immediate surgical consul tation. This patient population was entered into a prospective, randomized study of CT scan or US examination. RESULTS: Between May 1997 and May 1999, 106 patients were enrolled in the s tudy; 17 were later excluded from the study because of typical presentation and direct admission to surgery without diagnostic imaging. Forty-nine pat ients were randomly assigned to CT scan and 40 to US examination. CT scan w as 100% specific and 97% sensitive (P = 0.018). US was 90% specific and 76% sensitive. Based on the results of these imaging studies, 70 of the study patients underwent exploration for suspected appendicitis or other acute in flammatory process. CONCLUSION: A subset Of patients presenting with possible acute appendiciti s has been identified that should benefit from imaging of the appendix prio r to surgical consultation. For this group, CT scan appears superior to abd ominal and pelvic US in terms of diagnostic accuracy and reliability. With this approach, a low incidence of negative laparotomies was achieved. (C) 2 000 by Excerpta Medica, Inc.