A baby born to a young woman whose pregnancy was complicated by polyhydramnios was placed in the intensive care unit because of repeated vomiting containing bile. The stomach was markedly distended, and only small amounts of meconium had passed through the anus. What is the most likely diagnosis?

This baby is suffering from duodenal atresia at a level distal to the opening of the common bile duct. This causes a reflux of bile and its presence in the vomitus. The pregnancy was complicated by polyhydramnios because the duodenal atresia prevented passage of amniotic fluid into the intestines for absorption. This is not a case of esophageal atresia bcz in this case there is no bile in vomiting.