[Sonographic diagnosis of choledochus cysts]. 
Patients suffering from choledochus cysts are rare among the patients of a District Hospital.  We found only four choledochus cysts among about 70,000 sonographies performed during the past ten years, all of them in young women.  These patients show sonographically a liquid space-occupying lesion in the hepatic porta next to the gallbladder.  To safeguard the sonographic diagnosis an ERC or an i.v.  cholangiogram should always be performed preoperatively.  Operative removal should always be aimed at because of chronic recurring cholangitis and the relatively high risk of malignancy in the future.