This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Definite indication of intra -operative cholangiogram is? 
Select and explain. 
A. Preoperative USG showing non dilated CBD, B. Unclear biliary anatomy of the patient, C. Acute cholecystitis, D. Cholelithiasis
B: Unclear biliary anatomy of the patient
Answer: B: Unclear biliary anatomy of the patient 
Explanation: Intra/Preoperative cholangiography defines the biliary anatomy & is mainly used to exclude the presence of stones within the bileduct.In this technique,a catheter can be placed in cystic duct and contrast injected directly into the biliary tree Reference:Bailey & Love's manual of surgery,25th edition,page no:1116