This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Stomach and Intestines, Subject name: Pediatrics
3 month infants with abdominal palpable mass & non bilious vomiting - 
Select and explain. 
A. Hypertrophic biliary stenosis, B. Hypertrophic pyloric stenosis, C. Tracheoesophageal fistula, D. Duodenal atresia
B: Hypertrophic pyloric stenosis
Answer: B: Hypertrophic pyloric stenosis 
Explanation: Ans. is 'b' i.e., Hypertrophic pyloric stenosis Hypertophic pyloric stenosiso Most common cause of nonbilious vomiting is Hypertrophic pyloric stenosis,o Male > female.o Vomiting starts with 3 week of age.o Palpable mass is seen in epigastric region,o Visible peristalsis is seen soon after feeding,o Confirmed by USG abdomen,o Contrast study shows :Shoulder signDouble tract sign.o Treatment surgery = Ramstedt procedure.