How is the dx of choledocholethiasis?

US (visualizes stones in only 50% cases, but can see dilation of duct 75%, cannot exclude it definitely) MRCP (non invasive, visualizes duct more accurately, can exclude or confirm choledocholithiasis) EUS (more invasive than US, visualizes duct more accurately, sensitivity 98% compared w/ERCP) If low probability we use EUS/MRCP (less invasive than ERCP) ERCP (sensitive and specific 95%, but only therapeutic usually)