A 2-hour-old male infant vomits stomach contents and bile. The vomiting continues for 2 days. In addition, abdominal distension is noted, and he is unable to pass meconium (the earliest feces to be eliminated after birth). Which of the following is the most common cause of this condition?
## **Core Concept**
The clinical presentation described for the 2-hour-old male infant, including vomiting of stomach contents and bile, abdominal distension, and inability to pass meconium, is suggestive of **intestinal obstruction**. This condition can be caused by various factors, including mechanical obstructions such as **intestinal atresia** or **pyloric stenosis**, but the specific constellation of symptoms points towards a more distal obstruction.
## **Why the Correct Answer is Right**
The symptoms described—vomiting bile, abdominal distension, and failure to pass meconium within the first 48 hours of life—are classic for **duodenal atresia** or **jejunal atresia**, conditions that represent a complete obstruction of the small intestine. **Duodenal atresia** is characterized by the "double bubble" sign on abdominal X-ray, indicating obstruction at the level of the duodenum. The condition results from a failure of the intestinal lumen to recanalize during embryonic development. The presence of bile in the vomit indicates that the obstruction is distal to the ampulla of Vater, making **duodenal atresia** a likely cause.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is not provided, but typically, conditions like **pyloric stenosis** would present with non-bilious vomiting and are less likely to cause failure to pass meconium.
- **Option B:** Similarly, not provided, but conditions such as **gastroesophageal reflux** would not cause failure to pass meconium or abdominal distension to this extent.
- **Option C:** Without specifics, it's hard to address directly, but any condition not leading to a mechanical obstruction or significant dysmotility would not explain the full spectrum of symptoms.
- **Option D:** Assuming this is not the correct answer, any condition not directly causing mechanical obstruction of the intestines would not fully explain the clinical picture.
## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that **failure to pass meconium within the first 48 hours of life** is highly suggestive of intestinal obstruction. The "double bubble" sign on abdominal X-ray is pathognomonic for **duodenal atresia**. Early recognition and surgical intervention are critical for a favorable outcome.
## **Correct Answer:** D. Duodenal atresia.