52 Decline in Total Serum Bilirubin Level Is Sensitive but Not Specific Marker for Spontaneous Common Bile Duct Stones Passage

Abstract

INTRODUCTION: Increased serum total bilirubin (T. bili: mg/dl) on presentation is one of the commonly used markers for the presence of common bile duct (CBD) stones. We sought to examine the relationship between the decrease in T. bili level and the probability of spontaneous stone passage in patients (pts) with suspected or confirmed choledocholithiasis. METHODS: Pts who were 18 or older and admitted to our institution between October 2015 and December 2017 with ICD 10 code(s) used in pts with confirmed or suspected choledocholithiasis were identified through the University of Kentucky Medical Services Database. Only pts with documented elevated T. bili with at least 3 measurements 12 hours apart were included for further review. Only pts with high-probability of choledocholithiasis based on very strong and/or strong clinical predictors of choledocholithiasis per ASGE guidelines were included in the final analysis. All selected pts underwent one or more of the following confirmatory studies: MRCP, ERCP, EUS or IOC. Categorical variables were compared using chi square tests and continuous variables using two-sample t-tests. Regression analysis was performed to identify independent variables associated with retained stone despite consistent decline in T. bili level. RESULTS: 825 pts were identified according to the screening criteria. 723 pts were excluded due to having pathologies and 102 pts were included in this study (48 males & 54 females). Mean age of 57.4 years ± 22. 33 pts had fluctuation or no decline in T. bili level and 30 of them (92%) were confirmed to have retained stones. Among the 75 pts with consistent decline in T. bili level after 48 hours from initial presentation, 26 (34.7%) were found to have retained stone while 49 (65.3%) were confirmed to have no retained stones (passed spontaneously). On regression analysis, predictors of the presence of retained CBD stone(s) despite consistent decline in T. bili level included: pts older than 55 (OR 1.9; 95% CI: 1.1, 3.4) and pts presented with severe cholangitis defined as WBC > 16,000 and hypotension (OR 1.6; 95% CI 1.2–2.7). CONCLUSION: Although consistent decline in T. bili level is a sensitive predictor for spontaneous CBD stone passage, it is not specific and can be seen in at least one third of patients with documented retained stones. Possible explanations for decreased specificity include vigorous medical support (hydration & antibiotics) that may contribute to decline in T. bili level even in the setting of retained stones.