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
Water loss is severe if intestinal obstruction occurs at? 
Select and explain. 
A. First pa of duodenum, B. Third pa of duodenum, C. Mid jejunum, D. Ileum
A: First pa of duodenum
Answer: A: First pa of duodenum 
Explanation: In high small bowel obstruction there is rapid vomiting and dehydration. Ref: Bailey & Love 25/e, Page 1193.