title: Whether intravenous contrast is necessary for CT diagnosis of acute appendicitis in adult ED patients?
abstract: OBJECTIVE
  To assess the necessity of intravenous contrast medium for abdominopelvic computed tomography (CT) diagnosis of acute appendicitis (APP) among adult patients with right lower quadrant (RLQ) abdominal pain at emergency department (ED).
  
  
  METHODS
  ED patients with clinical suspicion of APP from RLQ pain for a period of 8 months were enrolled retrospectively. Both pre- and postintravenous contrast-enhanced CT scans were performed for these patients. The visibility of vermiform appendix and specific CT findings of APP were recorded separately for noncontrast CT (NCT) and contrast-enhanced CT (CCT) images without knowledge of the patient's identity and final diagnosis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CT diagnosis for APP were compared between the two groups. The ease of identifying appendix was also compared.
  
  
  RESULTS
  Forty-two (42.0%) of the 100 patients (55 males, 45 females; age range, 16-90 years; mean age, 49.3 years) were APP. There was no significant difference for the visibility of appendix (94% vs. 91%; P = .589) and radiological characters between the CCT and NCT groups. There were significant differences between the two groups for sensitivity (100% vs. 90.5%; P = .036), specificity (94.8% vs. 100%; P = .038), PPV (93.3% vs. 100%; P = .021), NPV (100% vs. 93.5%; P = .021), but no significant difference for accuracy (97% vs. 96%; P = 1). The appendix was easier to detect on CCT than NCT images (P = .013).
  
  
  CONCLUSIONS
  The diagnostic sensitivity of CCT was significantly better than that of NCT. Intravenous contrast administration could also make doctors easier in indentifying appendixes.
authors.affiliation: Department of Emergency Medicine, Wan-Fang Hospital, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yu-Hui
authors.initials: YH
authors.lastname: Chiu
authors.forename: Jen-Dar
authors.initials: JD
authors.lastname: Chen
authors.forename: Shih-Hao
authors.initials: SH
authors.lastname: Wang
authors.forename: Chui-Mei
authors.initials: CM
authors.lastname: Tiu
authors.forename: Chorng-Kuang
authors.initials: CK
authors.lastname: How
authors.forename: Jiun-I
authors.initials: JI
authors.lastname: Lai
authors.forename: Yi-Hong
authors.initials: YH
authors.lastname: Chou
authors.forename: Carlos
authors.initials: C
authors.lastname: Lam
authors.forename: Ray-Jade
authors.initials: RJ
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001064:Appendicitis / Q000000981:diagnostic imaging*; D016009:Chi-Square Distribution; D003287:Contrast Media / Q000008:administration & dosage; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D007902:Length of Stay / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media