This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Stomach & Duodenum, Subject name: Surgery
String sign on barium meal is seen in: 
Select and explain. 
A. Duodenal atresia, B. Intestinal obstruction, C. Duodenal ulcer, D. Congenital hyperophic pyloric stenosis
D: Congenital hyperophic pyloric stenosis
Answer: D: Congenital hyperophic pyloric stenosis 
Explanation: Diagnosis: Palpation of the pyloric tumor or olive in the epigastrium or right upper quadrant by a skilled examiner is pathognomonic of the diagnosis of HPSQ If the olive is palpated, no additional diagnostic testing is necessaryQ. IOC - USG ABDOMEN. Barium Meal: - String SignQ:indicating a narrowed elongated pyloric canal that does not relax is seen - Shoulder SignQ caused by t he hyperophied muscle indenting the antrum - Double - track signQ: Caused by the redundant mucosa.