The least common form of neonatal air leak syndrome is:

• A. Pneumomediastinum
• B. Pneumopericardium
• C. Pneumothorax
• D. Pneumoperitoneum

Answer: (D)

Air leaks in newborns happen when alveolar rupture allows air to escape into tissue planes. The air tends to travel along the peribronchovascular sheaths into the mediastinum, so pneumomediastinum is the most common form. From there, air can spread into the pleural space to cause a pneumothorax or into the pericardial sac to cause pneumopericardium, which are progressively less common. Reaching the abdominal cavity requires air to cross diaphragmatic barriers, a much less likely route, so pneumoperitoneum is the least common form of neonatal air leak syndrome.