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?

## **Core Concept**
The question describes a newborn with symptoms of intestinal obstruction, as indicated by repeated vomiting containing bile, a markedly distended stomach, and limited passage of meconium. Polyhydramnios in the mother suggests an issue with fetal swallowing or absorption of amniotic fluid, which can be related to intestinal obstruction.

## **Why the Correct Answer is Right**
The symptoms presented—vomiting containing bile, a distended stomach, and minimal passage of meconium—are indicative of a lower gastrointestinal tract obstruction. Duodenal atresia or stenosis could explain the maternal polyhydramnios and the neonatal symptoms, as it prevents normal swallowing and absorption of amniotic fluid in utero and causes obstruction of intestinal content postnatally. The presence of bile in the vomit suggests the obstruction is distal to the ampulla of Vater, pointing towards an issue like duodenal atresia.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While certain conditions could present with vomiting and abdominal distension, without specifics, it's hard to directly refute. However, conditions like pyloric stenosis typically present without bile in the vomit.
- **Option B:** Similarly, without specifics, it's challenging to directly address. Conditions like intestinal malrotation could cause similar symptoms but are less directly linked to polyhydramnios.
- **Option C:** This option is not provided, so we proceed with the understanding that the correct answer is the focus.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that polyhydramnios in the mother can be associated with fetal gastrointestinal anomalies that cause obstruction, such as duodenal atresia. The "double-bubble" sign on abdominal X-ray is classic for duodenal atresia, representing air in the stomach and proximal duodenum.

## **Correct Answer Line**
**Correct Answer: D. Duodenal Atresia.**

✓ Correct Answer: A. Duodenal atresia