title: Computed tomography in the assessment of suspected large bowel obstruction.
abstract: BACKGROUND
  The aim of this study was to assess the efficacy of computed tomography (CT) scanning in the diagnosis of acute large bowel obstruction.
  
  
  METHODS
  Forty-four patients (22 men; 22 women, ages 39-94 years, mean 71 years) with clinical features and abdominal radiographic findings suggesting acute large bowel obstruction (LBO) or pseudo-obstruction were examined with CT. Supine scans were obtained with i.v. contrast medium (unless contraindicated), but (in the majority) without oral contrast. Additional prone and/or decubitus scans were obtained in 33 patients when clarification of a possible transition point on the supine scan was required. CT diagnosis of LBO was made by finding a transition point +/- mass. Final diagnosis was confirmed by surgery, further imaging and/or clinical course.
  
  
  RESULTS
  Twenty-two patients had proven mechanical acute LBO of whom 18 had an obstructing carcinoma; 22 patients had no mechanical obstruction. Sensitivity, specificity, Positive Predictive Value, Negative Predictive Value of CT for diagnosis of mechanical LBO were each 91%. Positive and negative likelihood ratios were 10.1 and 0.1, respectively. There were two false-negative CT scans, although one of these was reported as showing segmental mural thickening. A mass was identified on 14 of 17 patients with true-positive CT, subsequently found to have carcinoma.
  
  
  CONCLUSIONS
  Computed tomography with additional selective prone and/or decubitus scanning is highly effective in the diagnosis of mechanical LBO. It is suggested that it replace contrast enema as the initial imaging method.
authors.affiliation: Department of Colorectal Surgery, Royal Perth Hospital, Perth, Western Australia, Australia.
authors.forename: Garth C
authors.initials: GC
authors.lastname: Beattie
authors.forename: Robert T
authors.initials: RT
authors.lastname: Peters
authors.forename: Susanne
authors.initials: S
authors.lastname: Guy
authors.forename: Richard M
authors.initials: RM
authors.lastname: Mendelson
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007415:Intestinal Obstruction / Q000000981:diagnostic imaging*; D007420:Intestine, Large; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome