Question: what is type 1 choledochal cyst?
Answer: Type 1 — a cyst of the extrahepatic bile duct, accounting for up to 90% of all choledochal cysts. Type 2 — an abnormal pouch or sac opening from the duct. Type 3 — a cyst inside the wall of the duodenum. Type 4 — cysts on both the intrahepatic and extrahepatic bile ducts.