title: Factors related to the failure of radiographic recognition of occult posttraumatic pneumothoraces.
abstract: OBJECTIVE
  Although posttraumatic pneumothoraces (PTXs) are common and potentially life threatening, the supine chest radiograph (CXR) is an insensitive test for their detection. Computed tomography (CT) often identifies occult pneumothoraces (OPTXs). Previous descriptions of OPTX topography have been poor. Our purpose was to define their distribution and aid in the targeting of thoracic ultrasound.
  
  
  METHODS
  Posttraumatic supine CXRs and CTs were reviewed for occult, overt, and residual PTXs. PTXs were compared according to their apical, basal, anterior, lateral, medial, and posterior components. A comparative size index was calculated.
  
  
  RESULTS
  Among 761 patients, 338 CT scans revealed 103 PTXs in 89 patients; 55% were OPTXs. OPTXs were apical (57%), basal (41%), anterior (84%), lateral (24%), and medial (27%), with 0% posterior.
  
  
  CONCLUSIONS
  CXR missed over half of all PTXs. OPTXs had a greater anterior versus lateral (nearly 4-fold) and both basal and apical versus lateral (2-fold) distribution. OPTXs are often located at easily accessible sonographic windows.
authors.affiliation: Department of Surgery, Foothills Medical Centre, Room EG23, 1403-29 Street NW, Calgary, Alberta, Canada.
authors.forename: Chad G
authors.initials: CG
authors.lastname: Ball
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Kirkpatrick
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Laupland
authors.forename: Dan L
authors.initials: DL
authors.lastname: Fox
authors.forename: Stacey
authors.initials: S
authors.lastname: Litvinchuk
authors.forename: Dianne M M
authors.initials: DM
authors.lastname: Dyer
authors.forename: Ian B
authors.initials: IB
authors.lastname: Anderson
authors.forename: S Morad
authors.initials: SM
authors.lastname: Hameed
authors.forename: John B
authors.initials: JB
authors.lastname: Kortbeek
authors.forename: Rob
authors.initials: R
authors.lastname: Mulloy
mesh_terms: D005260:Female; D006801:Humans; D015601:Injury Severity Score; D008297:Male; D011030:Pneumothorax / Q000000981:diagnostic imaging*; D013902:Radiography, Thoracic / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D016683:Supine Position; D013898:Thoracic Injuries / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D014949:Wounds, Nonpenetrating / Q000000981:diagnostic imaging*