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
Initial investigation of choice for biliary obstruction
assistant
The correct answer is  Ultrasonography Initial imaging modality of choice in obstructive jaundice It is operator dependent and may be suboptimal due to excessive body fat and intraluminal bowel gas USG can demonstrate Biliary calculi Size of GB and CBD Thickness of GB wall Presence of inflammation around GB Occasionally, presence of stones within the biliary tree Ref: Sabiston 20th edition Pgno : 1487