Analysis of false-negative diagnoses on endoscopic brush cytology of biliary and pancreatic duct strictures - The experience at 2 university hospitals

Context.-Endoscopic brush cytology is a valuable technique for the diagnosi s of pancreatobiliary malignancy. Despite its widespread use, the sensitivi ty of this method has been reported as approximately 50%. The specificity i s usually higher than 95%. Few reports have systematically analyzed the rea sons for this relatively low sensitivity. Objectives.-To determine the rate and reasons for false-negative diagnoses in endoscopic brushing cytology of biliary and pancreatic ducts based on th e results of sensitivity, specificity, accuracy, and positive and negative predictive values. Design.-Retrospective analysis of laboratory data and slide review of false -negative cases. Setting.-Two tertiary care state university hospitals. Patients.-A total of 183 pancreatobiliary brushing; specimens obtained from patients undergoing endoscopic retrograde cholangiopancreatography for bil iary or pancreatic duct disease for a 4- to 5-year period. Intervention.-Endoscopic retrograde cholangiopancreatography brushings. Main Outcome Measures.-Determination of sensitivity, specificity, accuracy, and positive and negative predictive values. Analysis of false-negative re sults. Results.-The sensitivity, specificity, accuracy, and positive and negative predictive values, overall, were 48%, 98%, 79%, 92%, and 76%, respectively. Sampling error was a major cause of false-negative diagnoses (67%), follow ed by interpretive (17%) and technical errors (17%). Conclusions.-Improvements in sensitivity and diagnostic accuracy for cancer of the pancreatobiliary tract can be achieved by optimizing slide preparat ory techniques. Also, enhancement of the cytologist's diagnostic skills ena bles the identification of the morphologic features of premalignant lesions . Repeat brushings are indicated for suspicious or negative results not con sistent with the clinical or radiologic findings.