The rational use of computed tomography scans in the diagnosis of appendicitis

Background: Recently, limited abdominal computed tomography (CT) scans have been reported (Rao, New England Journal of Medicine, 1998) to have accuracy as high as 98%. We compare our hospital's CT accuracy ordered by emergency room (ER) physicians with that of experienced surgeons provided only with the ER history and physical examination in the evaluation of appendicitis. Methods: All charts of patients 16 years or older with limited CT scans ordered by ER from January 1, 1996, through February 28, 1998, were reviewed. CT scans ordered when appendicitis was not in the differential were excluded from analysis. Pathology and clinical follow-up were criterion standards. Four surgeons reviewed ER history and physical and placed them into one of three categories: appendectomy, observe to rule out appendicitis, or discharge with follow-up (included admitting to another service or treating for another disorder). Results: A total of 526 charts were reviewed; 129 met the criteria for the study. The accuracy of CT scans as used by our ER was not as high as reported in the literature. In addition, surgeon accuracy approached that of the CT scan even without the ability to evaluate the patients in person. Noncontrast CTs were ordered before surgical evaluation in contrast to the Rao protocol, likely reducing their accuracy. Conclusions: Ordering CT scans to evaluate for appendicitis prior to surgical evaluation is of limited value.