Impact of helical computed tomography on the rate of negative appendicitis

To assess the impact of helical computed tomography (HCT) on the rate of negative appendicitis (NA). A before-and-after comparison study comparing data from a prospective consecutive case series to data from a retrospective chart review. The prospective series included all patients presenting to the ED during a 19-month period, during which patients with suspected appendicitis were managed in accordance with a guideline that stipulated HCT in selected cases. The retrospective group included patients taken to the operating room (OR) with a preoperative diagnosis of appendicitis over a 4-year time frame before the use of HCT. The primary outcome variable was the rate of NA. During the HCT era, 104 of 310 patients, 71 (68%; 95% confidence interval [CI], 59-76) men and 33 (32%; 95% CI, 24-41) women, were taken to the OR with a diagnosis of appendicitis. Fourteen (13.5%; 95% CI, 8-21) were NA. During the pre-HCT period, 445 patients, 280 (62.9%; 95% CI, 58-67) men and 165 (37.1%; 95% CI, 33-42) women were taken to the OR with the preoperative diagnosis of appendicitis, and 66 (14.8%; 95% CI, 12-19) were NA. At the study institution, the selective use of HCT did not result in a significant decline in the rate of NA.