Dynamic liver test patterns do not predict bile duct stones

Numerous models have been developed to predict choledocholithiasis. Recent work has shown that these algorithms perform suboptimally. Identification of clinical predictors with high positive and negative predictive value would minimize adverse events associated with unnecessary diagnostic endoscopic retrograde cholangiopancreatography (ERCP) while limiting the use of expensive tests including magnetic resonance cholangiopancreatography (MRCP) and endoscopic ultrasound (EUS) for indeterminate cases.

Consecutive unique inpatients who received their first ERCP at Los Angeles County Medical Center between January 2010 and November 2016 for suspected bile duct stones were reviewed. The primary outcome was the proportion of patients with specific combinations of liver enzyme patterns, transabdominal ultrasound, and clinical features who had stones confirmed on ERCP. As a secondary outcome, we assessed the performance of the American Society for Gastrointestinal Endoscopy (ASGE) risk stratification algorithm in our population.

Of the 604 included patients, bile duct stones were confirmed in 410 (67.9%). Detailed assessment of liver enzyme patterns alone and in combination with clinical features and imaging findings yielded no highly predictive algorithms. Additionally, the ASGE high-risk criterion had a positive predictive value of only 68% for stones. For the 236 patients for whom MRCP was performed, this imaging modality was shown to have highest predictive value for the presence of stones on ERCP.

Exhaustive exploration of various threshold values and dynamic patterns of liver enzymes combined with clinical features and basic imaging findings did not reveal an algorithm to accurately predict the presence of stones on ERCP. The ASGE risk stratification criteria were also insensitive in our population. Though desirable, there may be no "perfect" combination of clinical features that correlate with persistent bile duct stones. MRCP or EUS may be considered to avoid unnecessary ERCP and associated complications.