title: Important CT findings for prediction of severe appendicitis: involvement of retroperitoneal space.
abstract: BACKGROUND
  Determination of the severity of appendicitis and differentiation between complicated and uncomplicated appendicitis are clinically important. Severe appendicitis frequently affects extraperitoneal spaces. We have investigated CT findings of retroperitoneal space (RPS) in patients with appendicitis to create a model for identification of complicated appendicitis.
  
  
  METHODS
  CT images of 223 patients with pathologically proven appendicitis were reviewed. The total number of the segments in RPS where inflammatory changes were located (RPS count) was obtained as well as appendiceal diameter, appendicolithiasis, WBC count, and CRP level. Data were analyzed to identify factors indicating complicated appendicitis. Univariate analysis was conducted to identify statistically significant variables. A multivariable logistic regression analysis was performed in order to find independent predictors of complicated appendicitis.
  
  
  RESULTS
  Patients with complicated appendicitis were more likely to have higher RPS count (P < 0.001), appendicolithiasis (P = 0.002), higher CRP level (P < 0.001), and greater appendix diameter (P < 0.001) than patients with uncomplicated appendicitis. Statistical analysis showed RPS count was the most helpful predictor of complicated appendicitis.
  
  
  CONCLUSIONS
  Radiologists and surgeons should be aware of the importance of CT findings in RPS when treating patients with appendicitis. Complicated appendicitis can be predicted by RPS count, diameter of the appendix, appendicolithiasis, and CRP level.
authors.affiliation: Department of Radiology Tokyo Medical University Hospital, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023 Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Kitaoka
authors.affiliation: Department of Radiology Tokyo Medical University Hospital, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023 Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Saito
authors.affiliation: Department of Radiology Tokyo Medical University Hospital, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023 Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Tokuuye
keywords: Appendicitis; CT; Complicated; Extraperitoneal space; Retroperitoneal space