title: The negative appendectomy rate: who benefits from preoperative CT?
abstract: OBJECTIVE
  The purpose of this article is to determine the negative appendectomy rates of patients who did and did not undergo preoperative CT and to determine, more specifically, whether men benefit from preoperative CT.
  
  
  METHODS
  We identified 512 patients who had a nonincidental appendectomy between July 1, 2002, and June 30, 2007. Pathology records were compared with a radiology records search to determine which patients underwent preoperative CT. Proportions of patients were compared between groups using the Fisher exact test.
  
  
  RESULTS
  Of 512 patients who had a nonincidental appendectomy, 465 (91%) underwent preoperative CT, and 47 (9%) underwent appendectomy only on the basis of clinical findings. Overall, 22 of 465 patients (4.7%) who underwent preoperative CT had a negative appendectomy compared with six of 47 patients who did not undergo preoperative imaging (negative appendectomy rate, 12.7%; p = 0.03). Among men, six of 237 (2.5%) with preoperative CT had a negative appendectomy, versus five of 42 without imaging (negative appendectomy rate, 11.9%; p = 0.01).
  
  
  CONCLUSIONS
  The negative appendectomy rate was decreased for adult patients who underwent preoperative CT compared with patients who did not undergo preoperative imaging. Although most prior studies have suggested that CT is efficacious only in decreasing the negative appendectomy rate among women, we found that men benefit from CT as well.
authors.affiliation: Department of Radiology, University of California, San Francisco, M372, Box 0628, 505 Parnassus Ave, San Francisco, CA 94143-0628, USA. emma.webb@radiology.ucsf.edu
authors.forename: Emily M
authors.initials: EM
authors.lastname: Webb
authors.forename: Alexander
authors.initials: A
authors.lastname: Nguyen
authors.forename: Zhen J
authors.initials: ZJ
authors.lastname: Wang
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Stengel
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Westphalen
authors.forename: Fergus V
authors.initials: FV
authors.lastname: Coakley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy / Q000706:statistics & numerical data*; D001064:Appendicitis / Q000000981:diagnostic imaging* / Q000601:surgery*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012737:Sex Factors; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media; D007472:Iohexol