A newborn infant develops respiratory distress immediately after birth. His abdomen is scaphoid. No breath sounds are heard on the left side of his chest, but they are audible on the right. Immediate intubation is successful with little or no improvement in clinical status. Emergency chest x-ray is shown (A) along with an x-ray 2 hours later (B). Which of the following is the most likely explanation for this infant’s condition?

**Core Concept**
Diaphragmatic hernia is a congenital anomaly where there is a defect in the diaphragm, allowing abdominal contents to herniate into the thoracic cavity, which can cause respiratory distress in newborns.

**Why the Correct Answer is Right**
The infant's scaphoid abdomen and absence of breath sounds on the left side suggest a left-sided diaphragmatic hernia. The chest x-ray shows bowel loops and possibly the stomach within the left thoracic cavity, confirming the diagnosis. The herniated abdominal contents compress the left lung, causing respiratory distress. The immediate improvement with intubation is due to the relief of the respiratory compression.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not explain the scaphoid abdomen and the absence of breath sounds on the left side.
**Option B:** This option is incorrect as it does not account for the herniated abdominal contents seen on the chest x-ray.
**Option C:** This option is incorrect as it does not explain the specific findings of scaphoid abdomen and absent breath sounds on the left side.

**Clinical Pearl / High-Yield Fact**
A scaphoid abdomen in a newborn should raise the suspicion of congenital diaphragmatic hernia, which is a surgical emergency requiring prompt diagnosis and intervention.

**Correct Answer: D. Congenital diaphragmatic hernia.**

✓ Correct Answer: C. Diaphragmatic hernia