Recurrent common bile duct stones composed of ursodeoxycholic acid: a report of four cases.

Ursodeoxycholic acid (UDCA) is often used to treat cholesterol gallstones. UDCA makes cholesterol stones soluble, thereby improving biliary emptying. Conversely, however, UDCA can also form stones via an unknown mechanism, as shown in a few previous reports of cholangitis caused by the formation of UDCA stones in the common bile duct (CBD). We herein report four cases of recurrent cholangitis resulting from UDCA stones. The withdrawal of UDCA administration was highly effective in these patients. The details of these four cases suggest that clinicians must rethink the indications for UDCA treatment in cases in which cholangitis caused by CBD stones frequently recurs over a short period of time.