title: American Association for the Surgery of Trauma grade 4 renal injury substratification into grades 4a (low risk) and 4b (high risk).
abstract: OBJECTIVE
  We identified computerized tomography findings associated with the need for urgent intervention for hemostasis after traumatic renal injury to update and refine the American Association for the Surgery of Trauma Organ Injury Scale for renal trauma.
  
  
  METHODS
  We retrospectively reviewed the records of consecutive patients presenting to our level I trauma center from 1999 to 2008 with American Association for the Surgery of Trauma grades 3 and 4 renal injury. In all patients initial abdominal computerized tomography was done soon after presentation to the emergency department before renal intervention. All images were interpreted by a staff radiologist and urologist blinded to clinical outcomes. Novel radiographic features (perirenal hematoma size, intravascular contrast extravasation and renal laceration site) were analyzed and correlated with the invasive intervention rate to control life threatening bleeding.
  
  
  RESULTS
  Of 299 patients hospitalized with renal injury 102 met study inclusion criteria. Increased perirenal hematoma size (perirenal hematoma rim distance greater than 3.5 cm), intravascular contrast extravasation and a medial renal laceration site were important radiographic risk factors significantly associated with intervention for bleeding after renal trauma. Analyzing these radiographic characteristics collectively showed that patients with 0 or 1 risk factor were at 7.1% risk for intervention and those with 2 or 3 were at remarkably higher risk, that is 66.7% (OR 26.0, 95% CI 7.20-93.9, p <0.0001).
  
  
  CONCLUSIONS
  On radiography a large perirenal hematoma, intravascular contrast extravasation and medial renal laceration are important risk factors associated with the need for urgent hemostatic intervention after renal trauma. Assessing these computerized tomography characteristics collectively shows that American Association for the Surgery of Trauma grade 4 renal injuries can and should be substratified into grades 4a (low risk) and 4b (high risk).
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, Texas 75390-9110, USA.
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Dugi
authors.forename: Allen F
authors.initials: AF
authors.lastname: Morey
authors.forename: Amit
authors.initials: A
authors.lastname: Gupta
authors.forename: Geoffrey R
authors.initials: GR
authors.lastname: Nuss
authors.forename: Geraldine L
authors.initials: GL
authors.lastname: Sheu
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Pruitt
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D015601:Injury Severity Score; D007668:Kidney / Q000000981:diagnostic imaging* / Q000293:injuries*; D022125:Lacerations / Q000145:classification* / Q000000981:diagnostic imaging*; D008297:Male; D012189:Retrospective Studies; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed; D014949:Wounds, Nonpenetrating / Q000145:classification* / Q000000981:diagnostic imaging*; D014950:Wounds, Penetrating / Q000145:classification* / Q000000981:diagnostic imaging*