title: Rate of intra-abdominal injury after a normal abdominal computed tomographic scan in adults with blunt trauma.
abstract: OBJECTIVE
  The objective of this study is to determine the rate of intra-abdominal injury (IAI) in adults with blunt abdominal trauma after a normal abdominal computed tomographic (CT) scan. We hypothesize that the risk of subsequent IAI is so low that hospital admission and observation for possible IAI are unnecessary.
  
  
  METHODS
  We conducted a prospective, observational cohort study of adults (>18 years) with blunt trauma who underwent abdominal CT scanning in the emergency department. Computed tomographic scans were obtained with intravenous contrast but no oral contrast. Abnormalities on abdominal CT included all visualized IAIs or any finding suggestive of possible IAI. Patients were followed up to determine the presence or absence of IAI and the need for therapeutic intervention if IAI was identified.
  
  
  RESULTS
  Of the 3103 patients undergoing abdominal CT, 2734 (88%) had normal CT scans. The median age was 39 years (interquartile range, 26-51 years); and 2141 (78%) were admitted to the hospital. Eight (0.3%; 95% confidence interval, 0.1%-0.6%) were identified with IAIs after normal abdominal CT scans including the following injuries: pancreas (5), liver (4), gastrointestinal (2), and spleen (2). Five underwent therapy at laparotomy. Abdominal CT had a likelihood ratio (+) of 20.9 (95% confidence interval, 17.7-24.8) and likelihood ratio (-) of 0.034 (0.017-0.068).
  
  
  CONCLUSIONS
  Adult patients with blunt torso trauma and normal abdominal CT scans are at low risk for subsequently identified IAI. Thus, hospitalization for evaluation of possible IAI after a normal abdominal CT scan is unnecessary in most cases.
authors.affiliation: Department of Emergency Medicine, UC Davis School of Medicine, Sacramento, CA, USA. jfholmes@ucdavis.edu
authors.forename: James F
authors.initials: JF
authors.lastname: Holmes
authors.forename: John P
authors.initials: JP
authors.lastname: McGahan
authors.forename: David H
authors.initials: DH
authors.lastname: Wisner
mesh_terms: D000007:Abdominal Injuries / Q000000981:diagnostic imaging*; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data; D011446:Prospective Studies; D012307:Risk Factors; D014057:Tomography, X-Ray Computed; D014193:Trauma Centers / Q000706:statistics & numerical data; D014949:Wounds, Nonpenetrating / Q000000981:diagnostic imaging*; D055815:Young Adult