You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Which of the following is an etiological factor in Mirizzi's syndrome? and explain in detail?
Mirizzi's syndrome refers to obstruction of common hepatic duct resulting from compression by a gallstone impacted in the cystic duct. Two types of Mirizzi's syndrome are: Type I : Hepatic duct is compressed by a large stone impacted in the cystic duct or Haman's pouch. Type II: Calculus has eroded into the hepatic duct to produce a cholecystocholedochal fistula. Investigations: Ultrasonography reveals gallstones with a contracted gallbladder and moderate intrahepatic ductal dilatation with normal extrahepatic biliary anatomy.