A term newborn develops severe respiratory distress within hours of birth. Chest X-ray shows multiple air-filled bowel loops in the left hemithorax with mediastinal shift to the right and a scaphoid abdomen. The defect arises from failure of which structure?

• A Pleuroperitoneal membrane on the left ✓
• B Septum transversum
• C Dorsal mesentery of the oesophagus
• D Pleuropericardial folds

Explanation

Congenital diaphragmatic hernia of Bochdalek results from failure of the pleuroperitoneal membrane to close the pericardioperitoneal canal, usually on the left where this membrane closes later. Abdominal contents herniate into the thorax, causing pulmonary hypoplasia and respiratory distress. The septum transversum forms the central tendon, the dorsal mesentery forms the crura, and pleuropericardial folds form the fibrous pericardium, none of which explains a posterolateral hernia.

Reference: Langman's Medical Embryology, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.