Congenital diaphragmatic hernia

🕳️ Anatomy - A Hole in the Floor

A developmental defect in the diaphragm from incomplete fusion of pleuroperitoneal membranes, typically by week 8-10 of gestation. This allows abdominal viscera to enter the thorax.

• Bochdalek Hernia (Posterolateral):
  • Most common type (~85%).
  • Defect in the foramen of Bochdalek.
  • 📌 Bochdalek = Back & lateral.
• Morgagni Hernia (Anteromedial):
  • Rare, defect in the foramen of Morgagni.

⭐ 85% of Bochdalek hernias are on the left. The liver's position on the right may physically block herniation, and the right pleuroperitoneal canal closes earlier.

🌬️ Pathophysiology - Lungs Under Pressure

• Primary issue: Pulmonary hypoplasia & pulmonary hypertension, not the diaphragmatic hole itself. Herniation during lung organogenesis compresses the developing lungs, leading to:
  • ↓ Alveoli & bronchioles.
  • Thickened pulmonary arterioles → ↑ Pulmonary Vascular Resistance (PVR).
  • Commonly, surfactant deficiency.

⭐ The main cause of mortality is severe pulmonary hypoplasia and persistent pulmonary hypertension (PPHN), leading to right-to-left shunting and profound hypoxemia.

👶 Clinical Manifestations - The Empty Belly Blues

• Immediate Postnatal Distress:

  • Severe respiratory distress (cyanosis, tachypnea, retractions).
  • Often requires immediate intubation.

• Physical Exam Findings:

  • Scaphoid abdomen: "Empty belly" as contents are in the chest.
  • Barrel-shaped chest: Due to herniated viscera.
  • Auscultation: Bowel sounds in chest; ↓/absent breath sounds on affected side.
  • Displaced heart sounds: Apex beat shifted away from hernia.

⭐ Left-sided (Bochdalek) hernias are most common (~85%), leading to a rightward mediastinal shift.

🩺 Diagnosis - Seeing the Unseen

• Prenatal: Routine ultrasound may show polyhydramnios, an intrathoracic stomach bubble, and mediastinal shift.
• Postnatal:
  • Clinical: Severe respiratory distress at birth, scaphoid abdomen, barrel-shaped chest.
  • Auscultation: Bowel sounds in the chest; absent breath sounds on the affected side (usually left).

⭐ Chest X-ray is the definitive diagnostic test, showing gas-filled loops of bowel in the hemithorax and contralateral mediastinal shift.

🛠️ Management - The Repair Crew

• Initial: Intubate immediately, place NG tube for bowel decompression. ⚠️ Avoid bag-mask ventilation (insufflates stomach/bowel).
• Ventilation: Gentle, low-pressure ventilation; permissive hypercapnia is often targeted.
• Pulmonary HTN: Treat aggressively with inhaled nitric oxide (iNO), sildenafil.
• ECMO: Bridge to surgery for severe respiratory failure or refractory pulmonary hypertension.

⭐ The primary cause of mortality is pulmonary hypoplasia and persistent pulmonary hypertension (PPHN), not the hernia itself. Surgery is delayed until the patient is stable.

⚡ Biggest Takeaways

• Most common type is a left posterolateral Bochdalek hernia, allowing abdominal contents into the thorax.
• Pulmonary hypoplasia and pulmonary hypertension are the primary drivers of mortality, not the defect itself.
• Classic triad: respiratory distress from birth, a scaphoid abdomen, and bowel sounds in the chest.
• Initial management is critical: intubate immediately and place an orogastric tube. AVOID bag-mask ventilation.
• Surgical repair is performed only after medical stabilization, focusing on managing pulmonary hypertension.