title: Impact of helical computed tomography on the rate of negative appendicitis.
abstract: OBJECTIVE
  To assess the impact of helical computed tomography (HCT) on the rate of negative appendicitis (NA).
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  At the study institution, the selective use of HCT did not result in a significant decline in the rate of NA.
authors.affiliation: Department of Emergency Medicine, San Diego Medical Center, University of California, 92103, USA.
authors.forename: Tyler F
authors.initials: TF
authors.lastname: Vadeboncoeur
authors.forename: Robyn R
authors.initials: RR
authors.lastname: Heister
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Behling
authors.forename: David A
authors.initials: DA
authors.lastname: Guss
mesh_terms: D000293:Adolescent; D000328:Adult; D001062:Appendectomy; D001064:Appendicitis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D003287:Contrast Media; D004636:Emergency Service, Hospital; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D010043:Outcome and Process Assessment, Health Care; D011446:Prospective Studies; D012189:Retrospective Studies; D036542:Tomography, Spiral Computed
chemical_list: D003287:Contrast Media