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
Investigation of choice for gall bladder stone is: March 2010 
Select and explain. 
A. OCG, B. USG, C. PTC, D. X-ray
B: USG
Answer: B: USG 
Explanation: Ans. B: USG Investigation for gall stones: Ultrasound is the initial investigation of choice Diagnostic features on ultrasound include - Presence of gallstones - Distended thick-walled gallbladder - Pericholecystic fluid - Murphy's sign demonstrated with ultrasound probe If diagnostic doubt a HIDA scan may be useful-Will show failure of isotope (hydroxyiminodiacetic acid) uptake by gallbladder