Figure 1: Patient selection for MRCP and ERCP based on risk stratification. *For those individuals in whom CBD stones are suspected, the combination of abnormal liver function tests and a dilated CBD diameter (>7 mm) identify the vast majority of patients who have true, intraductal calculi. In this group, it is not unreasonable to proceed directly to ERCP. However, in those individuals who have only 1 of the 2 abnormalities present, the risk is intermediate, and hence MRCP as a noninvasive modality is needed. Those patients in whom neither liver function tests nor TAUS features are abnormal are at low risk of having intraductal stones and may proceed directly to cholecystectomy.