This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pancreas, Subject name: Surgery
In Carcinoma head of pancreas, Nausea & vomiting is due to: 
Select and explain. 
A. External Compression of duodenum, B. Portal vein infiltration, C. Proliferation infiltration of tumor into duodenum, D. Chemotherapy related
A: External Compression of duodenum
Answer: A: External Compression of duodenum 
Explanation: Ans. (a) External Compression of duodenumRef: Blumgarts 6th ed; pg. 979; Sabiston 20th ed; pg. 1544* Pancreatic adenocarcinoma develops in the ductal cells and are called Ductal Adenocarcinoma.* They most commonly occur on the Right side, i.e., Head and Uncinate Process (60-70%) than left side, i.e., Body and Tail of pancreas (20-25%)* Features of Carcinoma Head of Pancreas are# Jaundice 75%# Weight loss 51%# Abdominal pain 39%# Nausea/vomiting 13%# Pruritus 11%# Fever 3%# Gastrointestinal bleeding 1%* For tumors at the body and tail of pancreas, Pain (most common) and weight loss are the presenting features as they present at a late advanced stage* Regarding Nausea and vomiting, they occur due to tumor extrinsic compression of duodenum C loop presenting a state of Gastric outlet obstruction.* In unresectable cases, these patients should be offered Endoluminal duodenal metal stent as palliation.