A 25-days-old newborn presents to the emergency department with his parents. He has a distended abdomen and looks lethargic. The parents report that he has been feeding less during the last three days and vomited repeatedly. They describe the vomit as
bilious. This morning he produced stools with blood in them but he has
no fever. He was born at 35 weeks following premature rupture of membranes. Now he is otherwise healthy.
Given the most likely diagnosis, which one of the following investigations should be performed?
Abdominal U/S?
Abdominal x-ray?✅️
Laparotomy?
Test feed?
Upper gastrointestinal tract contrast study?