Prediction of common bile duct stones in the earliest stages of acute biliary pancreatitis

Background and study aims: Accurate prediction of common bile duct (CBD) stones in acute biliary pancreatitis is warranted to select patients for early therapeutic endoscopic retrograde cholangiopancreatography (ERCP). We evaluated commonly used biochemical and radiological predictors of CBD stones in a large prospective cohort of patients with acute biliary pancreatitis who were undergoing early ERCP. Patients and methods: 167 patients with acute biliary pancreatitis who were undergoing early ERCP (< 72 hours after symptom onset) in 15 Dutch hospitals in 2004-2007 were prospectively included. Abdominal ultrasonography and/or computed tomography (CT) was performed on admission and complete liver biochemistry determined daily. We used univariate logistic regression to assess associations between CBD stones found during ERCP (gold standard) and the following parameters: (1) clinical: age, sex, predicted severity; (2) radiological: dilated CBD, impacted stone in CBD; and (3) biochemical: bilirubin, gamma-glutamyl-transferase (GGT), alkaline phosphatase, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Results: Out of 167 patients, 94 (56%) had predicted severe acute biliary pancreatitis, 51 (31%) exhibited a dilated CBD and 15 (9%) had CBD stones on ultrasonography and/or CT. ERCP was performed at a median of 0 days (interquartile range 0-1) after admission. CBD stones were found during ERCP in 89/167 patients (53%). In univariate analysis, the only parameters significantly associated with CBD stones were GGT (per 10 units increase: odds ratio 1.02, 95% CI 1.01-1.03, P = 0.001) and alkaline phosphatase (per 10 units increase: odds ratio 1.03, 95% CI 1.00-1.05, P = 0.028). These and all other tested parameters, however, showed poor positive predictive value (ranging from 0.53 to 0.69) and poor negative predictive value (ranging from 0.46 to 0.67). Conclusions: The results of this study suggest that commonly used biochemical and radiological predictors of the presence of CBD stones during ERCP in the earliest stages of acute biliary pancreatitis are unreliable.