title: Does ultrasonography accurately diagnose acute cholecystitis? Improving diagnostic accuracy based on a review at a regional hospital.
abstract: BACKGROUND
  Acute cholecystitis is one of the most common diseases requiring emergency surgery. Ultrasonography is an accurate test for cholelithiasis but has a high false-negative rate for acute cholecystitis. The Murphy sign and laboratory tests performed independently are also not particularly accurate. This study was designed to review the accuracy of ultrasonography for diagnosing acute cholecystitis in a regional hospital.
  
  
  METHODS
  We studied all emergency cholecystectomies performed over a 1-year period. All imaging studies were reviewed by a single radiologist, and all pathology was reviewed by a single pathologist. The reviewers were blinded to each other's results.
  
  
  RESULTS
  A total of 107 patients required an emergency cholecystectomy in the study period; 83 of them underwent ultrasonography. Interradiologist agreement was 92% for ultrasonography. For cholelithiasis, ultrasonography had 100% sensitivity, 18% specificity, 81% positive predictive value (PPV) and 100% negative predictive value (NPV). For acute cholecystitis, it had 54% sensitivity, 81% specificity, 85% PPV and 47% NPV. All patients had chronic cholecystitis and 67% had acute cholecystitis on histology. When combined with positive Murphy sign and elevated neutrophil count, an ultrasound showing cholelithiasis or acute cholecystitis yielded a sensitivity of 74%, specificity of 62%, PPV of 80% and NPV of 53% for the diagnosis of acute cholecystitis.
  
  
  CONCLUSIONS
  Ultrasonography alone has a high rate of false-negative studies for acute cholecystitis. However, a higher rate of accurate diagnosis can be achieved using a triad of positive Murphy sign, elevated neutrophil count and an ultrasound showing cholelithiasis or cholecystitis.
authors.affiliation: The Vernon Jubilee Hospital, Vernon, BC, and the Faculty of Medicine, University of British Columbia, Vancouver, BC.
authors.forename: Hamish
authors.initials: H
authors.lastname: Hwang
authors.affiliation: The Vernon Jubilee Hospital, Vernon, BC.
authors.forename: Ian
authors.initials: I
authors.lastname: Marsh
authors.affiliation: The Vernon Jubilee Hospital, Vernon, BC, and the Faculty of Medicine, University of British Columbia, Vancouver, BC.
authors.forename: Jason
authors.initials: J
authors.lastname: Doyle
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002763:Cholecystectomy; D041881:Cholecystitis, Acute / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000601:surgery; D042883:Choledocholithiasis / Q000175:diagnosis / Q000000981:diagnostic imaging; D002769:Cholelithiasis / Q000175:diagnosis / Q000000981:diagnostic imaging; D003937:Diagnosis, Differential; D004630:Emergencies; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011785:Quality Assurance, Health Care; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D018615:Ultrasonography, Doppler, Color; D055815:Young Adult