What is the major contributor to risk for pulmonary hemorrhage among preterm infants?

• A. Patent ductus arteriosus (PDA)
• B. Pneumothorax
• C. Pulmonary interstitial emphysema (PIE)
• D. Pneumonia

Answer: (A)

The key idea is that a patent ductus arteriosus (PDA) with a significant left-to-right shunt increases pulmonary blood flow and elevates pulmonary capillary pressure. In a preterm infant, this added pressure stretches and can rupture the fragile pulmonary capillaries, leading to blood leaking into the airways and lung tissue—the hemorrhage. Closing the PDA or reducing its shunt lowers pulmonary pressures and reduces the risk of this bleed.

Other listed conditions can complicate the lungs, but they don’t create the sustained high pulmonary capillary pressures that a large PDA does, so they’re less directly linked to pulmonary hemorrhage in this context.