A 2-day-old term neonate presents with tachypnea, grunting, and cyanosis. Chest X-ray shows a 'white-out' left lung with mediastinal shift to the right and a scaphoid abdomen. The MOST likely diagnosis and the embryological defect responsible are:

• A Congenital lobar emphysema; failure of cartilage maturation
• B Cystic adenomatoid malformation; abnormal bronchial budding at 5–7 weeks
• C Pulmonary sequestration; anomalous systemic arterial supply to aberrant lung tissue
• D Left congenital diaphragmatic hernia (Bochdalek); failure of pleuroperitoneal membrane closure ✓

Explanation

The combination of respiratory distress, opacified hemithorax with contralateral mediastinal shift, and scaphoid abdomen (bowel in chest) is diagnostic of congenital diaphragmatic hernia (CDH), most commonly Bochdalek type (posterolateral, >95% on left side). The embryological defect is failure of the pleuroperitoneal membrane (posterior diaphragm) to close between weeks 8–10 of gestation, allowing herniation of abdominal viscera and resulting in ipsilateral pulmonary hypoplasia. The scaphoid abdomen distinguishes CDH from other causes of neonatal respiratory distress.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.