This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'The preferred bypass procedure in case of non resectable carcinoma of head of pancreas is- \nSelect and explain. \nA. Cholecystojejunostomy, B. Cholecystogastrostomy, C. Choledochoduodenostomy, D. Choledochojejunostomy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Surgery for advanced, non-resectable pancreatic adenocarcinoma can palliate obstruction of CBD or duodenum, as well as control visceral pain.\nHepaticojejunostomy, choledochojejunostomy or choledochoduodenostomy offers durable drainage of an obstructed bile duct.\nCholecystojejunostomy is less reliable but can be employed when tumor bulk precludes common duct procedure.\nGastrojejunostomy (antecolic anastomosis) palliates gastric outlet obstruction.\nAntecolic anastomosis\xa0is done to avoid complications from an expanding lesser sac tumor.', 'role': 'assistant'}]