The role of the Tokyo guidelines in the diagnosis of acute calculous cholecystitis. 
Acute calculous cholecystitis is a condition in which the gallbladder becomes inflamed due to cholelithiasis.  Early diagnosis reduces both mortality and morbidity.  The aim of this retrospective study was to assess the diagnostic value of the Tokyo guidelines in patients with acute cholecystitis.  The medical records of patients admitted for acute calculous cholecystitis proven by pathological findings were collected between January 2007 and June 2008.  Exclusion criteria included: acalculous cholecystitis, hepatobiliary malignancy, patients younger than 18 years and mortality unrelated to cholecystitis.  A total of 235 patients were classified into three groups according to the severity grading in the Tokyo guidelines.  Clinical characteristics among these patients were analyzed for comparison.  Among all diagnostic criteria, right upper quarter (RUQ) abdominal pain (97.9%) and thickened gallbladder wall (92.3%) had the highest sensitivity rates, whereas pericholecystic fluid collection (18.3%) and RUQ abdominal mass (0.8%) had the lowest sensitivity rates.  Higher sensitivity rates of diagnostic criteria were related to severe cholecystitis, except for Murphy's sign and white blood cell (WBC) count.  The presence of both RUQ abdominal pain and elevated C-reactive protein (55.1%), or both RUQ abdominal pain and elevated WBC count (53.7%), accounted for the highest sensitivity rates in making the definite diagnosis of acute cholecystitis.  Seventeen patients (7.2%) without comparable typical image findings were prone to be afebrile and had normal C-reactive protein values compared to those with typical image findings.  Among all diagnostic criteria in the Tokyo guidelines for acute cholecystitis, RUQ abdominal pain and thickened gallbladder wall had the highest sensitivity rates, and RUQ abdominal mass had the lowest sensitivity rate.  A combination of diagnostic criteria with different pathophysiologic findings, as noted in the Tokyo guidelines, can help clinicians make the correct diagnosis for patients with acute calculous cholecystitis.