The Bismuth-Corlette classification is used to describe the extent of hilar cholangiocarcinoma (Klatskin tumour). Type IV involvement means:

• A Tumour is confined to the common hepatic duct below the confluence
• B Tumour involves the confluence plus both right and left second-order intrahepatic ducts ✓
• C Tumour extends to the right second-order ducts but not left
• D Tumour involves the cystic duct and gallbladder only

Explanation

In Bismuth-Corlette classification: Type I — tumour below the confluence; Type II — involves the confluence only; Type IIIa — extends to right second-order ducts; Type IIIb — extends to left second-order ducts; Type IV — involves both right and left second-order intrahepatic ducts (multifocal or bilateral). Type IV carries the poorest prognosis and is typically considered unresectable as it prevents adequate biliary reconstruction after hepatectomy.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.