title: Abdominal imaging utilization in the emergency department: trends over two decades.
abstract: BACKGROUND
  To assess patterns of use of abdominal imaging in the emergency department (ED) from 1990 to 2009.
  
  
  METHODS
  We retrospectively reviewed data on adult ED patients treated between 1990 and 2009 at our university-affiliated quaternary care institution. Examinations were coded by abdominal imaging modality: x-ray, sonography, CT, or MRI. Proportional costs for each imaging modality were evaluated using relative value units (RVUs). Chi-square tests were used to assess for significant trends.
  
  
  RESULTS
  The intensity of abdominal imaging per 1,000 ED visits increased 19.3% from 1990-2009 (p = 0.0050). The number of abdominal CT scans per 1,000 ED visits increased 17.5-fold (p < 0.0001). Similarly, the number of abdominal MRIs per 1,000 ED visits increased from 0 to 1.0 (p < 0.0001), and the number of abdominal sonographs per 1,000 ED visits increased 51.6% (p = 0.0198). However, the number of x-ray examinations per 1,000 ED visits decreased 81.6% (p < 0.0001). Abdominal imaging RVUs per 1,000 ED visits increased 2.7-fold (p < 0.0001), due primarily to CT imaging, which accounted for 14% of RVUs in 1990 and 76% of RVUs in 2009.
  
  
  CONCLUSIONS
  The intensity of abdominal imaging examinations per 1,000 ED visits and the number of abdominal imaging RVUs increased significantly over a 20-year period. CT replaced x-ray as the most common abdominal imaging modality for evaluation of ED patients. In light of these increasing costs as well as the increased radiation exposure of CT, clinical decision rules and computerized decision support may be needed to ensure appropriate utilization of abdominal CT in the ED.
authors.affiliation: Center for Evidence-Based Imaging, Brigham and Women's Hospital, 75 Francis St., Boston, MA, USA.
authors.forename: Ali S
authors.initials: AS
authors.lastname: Raja
authors.forename: Koenraad J
authors.initials: KJ
authors.lastname: Mortele
authors.forename: Richard
authors.initials: R
authors.lastname: Hanson
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Sodickson
authors.forename: Richard
authors.initials: R
authors.lastname: Zane
authors.forename: Ramin
authors.initials: R
authors.lastname: Khorasani