This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET 2018, Subject name: Surgery
Most appropriate initial method of investigation for carcinoma head of pancreas: 
Select and explain. 
A. Laparoscopic guided biopsy, B. MRI guided biopsy, C. CECT guided biopsy, D. EUS guided transgastric biopsy
D: EUS guided transgastric biopsy
Answer: D: EUS guided transgastric biopsy 
Explanation: -Sensitivity of the USG is max when - Dist. b/w probe and organ is min. PA OF PANCREAS PROBE LOCATION Tail of Pancreas Stomach Head & Uncinate Process Duodenum Investigation for carcinoma head of pancreas: If the tumour size is < 1 cm and localised to small ducts and acini the preferred investigation modality is endoscopic USG, trans gastric biopsy. EUS is preferred because the distance is less between the probe and pancreas endoscopically and field of view is higher. Though trans gastric biopsy is not mandatory. It can be performed for histological confirmation and also avoids spillage of tumour cells. Histological confirmation is desirable but not essential as there is intense desmoplastic reaction in Ca head of pancreas, hence biopsy not mandatory as it cannot rule out the malignancy.