Predictive factors in the differential diagnosis of benign and malignant causes in patients undergoing endoscopic retrograde cholangiopancreatography for extrahepatic cholestasis

OBJECTIVE: Diagnosing benign vs. malignant extrahepatic cholestasis is challenging despite the currently available advanced imaging and endoscopic techniques. This study aims to determine the predictive accuracy of initial biochemical data and bile duct dilatation findings in transabdominal ultrasound (US) to differentiate between benign and malignant disease in patients with extrahepatic cholestasis. PATIENTS AND METHODS: We reviewed the case records of 814 patients who had undergone endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic cholangiography (in cases of unsuccessful ERCP) for extrahepatic cholestasis. The etiology of biliary obstruction was determined based on ERCP, endoscopic ultrasonography, radiology, cytology, biopsy, and/or clinical follow-up at one year. The patients were divided into benign and malignant groups according to the underlying etiology of biliary obstruction. A complete biochemical profile, transabdominal ultrasonography at presentation, and other demographic data were recorded. RESULTS: Alkaline phosphatase (p = 0.002), aspartate aminotransferase (p = 0.038), and bilirubin levels were significantly higher in malignant patients. The mean age of patients with malignancy was 69.5 years, vs. 60.6 years in benign patients (p < 0.001). The likelihood of malignancy increased with the increased bilirubin levels (> 200 mu mol/l: 30.0% sensitivity, 97.6% specificity). The total bilirubin level predicting malignancy as the best cut-off value was 111 mmol/L with optimum sensitivity and specificity (61.8% and 83.8%, respectively) and area under the curve = 0.756, (p < 0.001). Intrahepatic bile duct (IHBD) dilatation was significantly higher in malignant patients (p < 0.001). CONCLUSIONS: A serum bilirubin level of 111 mu mol/L or higher and the detection of IHBD dilatation on abdominal ultrasonography are important predictors in the differential diagnosis of benign and malignant causes of extrahepatic cholestasis