This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdominal Radiography, Subject name: Radiology
Double bubble sign is seen in:- 
Select and explain. 
A. Duodenal Atresia, B. Jejunal atresia, C. Ileal atresia, D. Hypertrophic pyloric stenosis
A: Duodenal Atresia
Answer: A: Duodenal Atresia 
Explanation: Ans. (a) Duodenal AtresiaRef.: SRB manual of Surgery, 4th ed. /1280* The diagnosis of duodenal atresia on X ray abdomen shows two large air filled spaces, called "double bubble" sign.* The air is trapped in the stomach and proximal duodenum, which are separated by the pyloric sphincter, creating the appearance of two bubbles visible on x-ray.* Since the closure of the duodenum is complete in duodenal atresia, no air is seen in the distal duodenum.