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
Features of pyloric stenosis : 
Select and explain. 
A. Hypokalemic alkalosis, B. Peristalsis right to left, C. Commonly caused by carcinoma stomach, D. Retention vomiting present
A: Hypokalemic alkalosis
Answer: A: Hypokalemic alkalosis 
Explanation: Ans. is 'a' i.e. hypokalemic alkalosis Gastric peristalsis is seen passing from left to right across the upper abdomen. Retention vomiting means vomiting due to any mechanical obstruction occurring usually hours after ingestion of a meal. In hyperophic pyloric stenosis the vomiting usually occurs 10 to 30 min. after the feed (Though in neglected undiagnosed cases the stomach becomes dilated and the vomiting becomes regurgitant in type occurring only once or twice every 24 hrs)