Todani classification
- Type I (most common, ~80%) — fusiform dilatation of the extrahepatic bile duct
- Type II — supraduodenal diverticulum
- Type III (choledochocele) — intra-duodenal cyst
- Type IV — multiple intra- and extrahepatic cysts
- Type V (Caroli disease) — intrahepatic only; may require liver resection or transplant

