This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hereditary Hyperbilirubinemia & Jaundice, Subject name: Medicine
In Bouveret syndrome, gall stone is impacted in: 
Select and explain. 
A. Pylorus, B. Jejunum, C. Terminal ileum, D. Ileocaecal valve
A: Pylorus
Answer: A: Pylorus 
Explanation: Bouveret syndrome: Impaction of a gallstone in the pylorus or proximal duodenum Resulting in gastric outlet obstruction Usually seen in elderly women Clinical presentation is usually nausea, vomiting, and epigastric pain due to gastric outlet obstruction