<Todani classification>
Type I: Most common variety (77-87%) involving saccular or fusiform dilatation of a portion or entire common bile duct (CBD) with normal intrahepatic duct.
![](https://blogimg.goo.ne.jp/user_image/16/5b/bac1c234ce9751b3fc5e1ed42ce18f98.jpg)
Type II: Isolated diverticulum protruding from the CBD(1.2-3%).
![](https://blogimg.goo.ne.jp/user_image/6f/83/2300debc0c194633a6bef2049349a004.jpg)
Type III or Choledochocele: Arise from dilatation of duodenal portion of CBD or where pancreatic duct meets(1.4-6%).
![](https://blogimg.goo.ne.jp/user_image/26/b9/35ccef6cf8682396ba513ac9662d7d9c.jpg)
Type IVa: Characterized by multiple dilatations of the intrahepatic and extrahepatic biliary tree(19%).
Type IVb: Multiple dilatations involving only the extrahepatic bile ducts(rare).
![](https://blogimg.goo.ne.jp/user_image/27/c6/8a6b1a78633725ffd63393ed5ce4ecf6.jpg)
Type V or Caroli's disease: Cystic dilatation of intra hepatic biliary ducts(rare).
Type I: Most common variety (77-87%) involving saccular or fusiform dilatation of a portion or entire common bile duct (CBD) with normal intrahepatic duct.
![](https://blogimg.goo.ne.jp/user_image/16/5b/bac1c234ce9751b3fc5e1ed42ce18f98.jpg)
Type II: Isolated diverticulum protruding from the CBD(1.2-3%).
![](https://blogimg.goo.ne.jp/user_image/6f/83/2300debc0c194633a6bef2049349a004.jpg)
Type III or Choledochocele: Arise from dilatation of duodenal portion of CBD or where pancreatic duct meets(1.4-6%).
![](https://blogimg.goo.ne.jp/user_image/26/b9/35ccef6cf8682396ba513ac9662d7d9c.jpg)
Type IVa: Characterized by multiple dilatations of the intrahepatic and extrahepatic biliary tree(19%).
Type IVb: Multiple dilatations involving only the extrahepatic bile ducts(rare).
![](https://blogimg.goo.ne.jp/user_image/27/c6/8a6b1a78633725ffd63393ed5ce4ecf6.jpg)
Type V or Caroli's disease: Cystic dilatation of intra hepatic biliary ducts(rare).
![](https://blogimg.goo.ne.jp/user_image/20/f3/6f7cdb343bfd5703b4c1f98cb6c9c49f.jpg)