Double bubble sign in children seen in A/E –: (A) Ladds band, (B) Annular pancreas, (C) Pancreatic pseudocyst, (D) Diaphragmatic hernia
Answer is D. Obstruction of 2nd part of duodenum cause double bubble sign on plain abdominal radiograph. OIt may be due to -

i)  Annular pancreas
ii) Pancreatic pseudocyst
iii) Ladds band                         
iv) Tumor in the head of the pancrease