Congenital thoracic abnormality associated with pulmonary hypoplasia and increased PPHN risk?

• A. Tracheoesophageal fistula
• B. Congenital diaphragmatic hernia (correct)
• C. Pulmonary sequestration
• D. Pulmonary hemorrhage

Answer: (B)

A congenital diaphragmatic hernia is a thoracic abnormality where abdominal organs herniate into the chest through a diaphragmatic defect, usually on the left side. This intrusion disrupts normal lung development, leading to pulmonary hypoplasia with a reduced pulmonary vascular bed. After birth, the already high resistance in the small, hypoplastic lungs persists or worsens, promoting right-to-left shunting through fetal channels (foramen ovale and ductus arteriosus) and resulting in persistent pulmonary hypertension of the newborn.

Other congenital thoracic conditions listed don’t typically cause pulmonary hypoplasia with a high risk of PPHN in the same way. Tracheoesophageal fistula involves airway and esophageal continuity issues but isn’t primarily about lung underdevelopment. Pulmonary sequestration is an extra lung tissue anomaly with its own blood supply, not characteristically linked to hypoplastic lungs or PPHN. Pulmonary hemorrhage is a complication rather than a congenital thoracic malformation that drives primary hypoplasia and PPHN risk.