<prompt> A 7-day old infant presents with bilious vomiting and gross abdominal distention with absent bowel sounds. X ray abdomen shows multiple gas filled loops. Diagnosis is?Hirschsprung diseaseCongenital Hyperophic pyloric stenosisDuodenal atresiaMalrotation of gut  <response>: Hirschsprung disease: No passage of meconium within 24 hours Abdominal distension Involvement rectum sigmoid No vomiting Congenital Hyperophic pyloric stenosis: Misnomer hyperophic pyloric stenosis is acquired Therefore, known as infantile hyperophic pyloric stenosis Age of presentation is 4th to 6th week after bih Non bilious vomiting Duodenal atresia: Symptomatic just after bih Bilious vomiting Double bubble sign therefore multiple gas filled loops are not seen Malrotation of gut: Bilious vomiting Abdominal distention Multiple gas filled loops 