Stella Kang MD, Abstract Co-Author: Nothing to Disclose

Laura Heacock MS, MD, Presenter: Nothing to Disclose

The American Society of Gastroenterology (ASGE) guidelines on evaluation of suspected choledocholithiasis generally support MRCP for intermediate risk patients, and direct evaluation with ERCP for high-risk patients. However, frail patients at high risk of choledocholithiasis but also procedural complications may benefit from MRCP, with the tradeoff of possible delay in necessary stone extraction. We evaluated the predictive utility of ASGE guideline variables and imaging parameters in risk stratification as a potential decision aid for choosing MRCP or ERCP.

We retrospectively reviewed inpatient cases at our institution with clinically suspected choledocholithiasis. Included patients had US or CT of the abdomen followed by MRCP within 48 hours. Reference standard included ERCP, endoscopic ultrasound, intraoperative cholangiogram, or documented clinical resolution. We used binary logistic regression to test 5 variables in ASGE risk assessment (total bilirubin, age, common duct (CD) dilatation, pancreatitis, liver function test (LFT) abnormality) according to published guidelines, as well as CD size at US/CT, for prediction of choledocholithiasis.

78 cases were included in regression analysis with 25 cases of CD stones. Among ASGE variables for risk assessment, abnormal LFT and CD dilatation were significant predictors of choledocholithiasis (p = 0.031, 0.017). Inclusion of all ASGE variables was slightly more accurate than the two-variable model (77 vs 75% accuracy).  Within the ASGE high risk group, CD dilatation was a significant predictor of choledocholithiasis.  In the ASGE high risk class, CD stone prevalence was 53%, and CD dilatation had positive predictive value (PPV) of 75%; meanwhile, ASGE intermediate risk patients had 22% CD stone prevalence, and CD dilatation had a PPV of only 26%.

For acutely ill patients, CD dilatation is the strongest predictor of choledocholithiasis and may aid the decision for MRCP versus ERCP. Patients classified as ASGE high risk for choledocholithiasis with CBD dilatation on initial imaging have high pretest probability not warranting MRCP.  ASGE intermediate risk patients cannot be reclassified to high risk using CD dilatation.

CD dilatation at initial imaging is the strongest predictor of choledocholithiasis in hospitalized patients and use with established clinical guidelines aids the decision for MRCP versus ERCP.

Kang, S, Heacock, L, Role of Initial Imaging in Risk Stratification for Suspected Choledocholithiasis in Hospitalized Patients.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045622.html