system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 74-year-old woman complains of vomiting and intermittent colicky abdominal pain. X- rays reveal fluid levels and air in the biliary tree. What is the likely cause?
assistant
The correct answer is  Gallstone ileus results in "tumbling" intestinal obstruction due to the intermittent nature of the condition. Previous choledochoduodenostomy could give air in the biliary tree but not obstruction.