title: Alternative diagnoses to suspected appendicitis at CT.
abstract: OBJECTIVE
  To assess alternative diagnoses in adults undergoing computed tomography (CT) for suspected acute appendicitis in routine clinical practice.
  
  
  METHODS
  This retrospective study was HIPAA compliant and institutional review board approved; informed consent was waived. A total of 1571 consecutive adults were referred from emergency department or urgent care settings for evaluation of suspected acute appendicitis at a single academic medical center from January 2006 to December 2009. Diagnoses given by board-certified radiologists at nonfocused abdominopelvic CT and ultimate clinical diagnoses by a combination of clinical, surgical, pathologic, and other radiologic findings were analyzed. Comparisons were made by using the Fisher exact test and Mann-Whitney test, where appropriate, with a two-tailed P value of less than .05 used as the criterion for statistical significance.
  
  
  RESULTS
  A specific diagnosis at CT examination was made in 867 of 1571 (55.2%) patients. Acute appendicitis was favored in 371 of 1571 (23.6%) patients. An alternative diagnosis other than appendicitis was suggested in 496 of 1571 (31.6%) patients. Among patients with an alternative CT diagnosis, 204 of 496 (41.1%) were hospitalized and 109 of 496 (22.0%) underwent surgical or image-guided intervention for diagnoses other than appendicitis, compared with rates of 14.1% and 4.4%, respectively, among patients in whom a specific diagnosis was not made at CT (P < .0001). The most common broad categories of disease included nonappendiceal gastrointestinal conditions (46.0%), gynecologic conditions (21.6%), genitourinary conditions (16.9%), and hepatopancreaticobiliary conditions (7.7%).
  
  
  CONCLUSIONS
  In adult patients clinically suspected of having acute appendicitis, abdominopelvic CT frequently identifies an alternative cause for symptoms, which often requires hospitalization and surgery for treatment.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252, USA.
authors.forename: B Dustin
authors.initials: BD
authors.lastname: Pooler
authors.forename: Edward M
authors.initials: EM
authors.lastname: Lawrence
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001064:Appendicitis / Q000000981:diagnostic imaging*; D003287:Contrast Media; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol