Description

• Defect in the diaphragm allowing herniation of abdominal contents into the thoracic cavity, causing varying degrees of pulmonary hypoplasia
• There are four types of congenital diaphragmatic hernia (CDH):
  • Bochdalek hernia (posterolateral location)
  • Morgagni hernia (lateral retrosternal location)
  • Pars sternalis (medial retrosternal)
  • Anterolateral

Epidemiology

• 1:2,000 to 5,000 live births
• Left sided in 85–90%
• Right-sided and bilateral defects less common
• Familial recurrence 2%

Risk Factors

Pregestational diabetes and alcohol use associated with increased risk

Pathophysiology

• Diaphragm arises from four elements and is complete by 8 weeks’ gestation.
  • Septum transversum, which becomes the central tendon of the diaphragm
  • Pleuroperitoneal membranes, which extend from the lateral body wall and fuse with the septum transversum and esophageal mesentery
  • Mesentery of the esophagus, which becomes the crura of the diaphragm
  • Lateral body wall from which myocytes migrate to muscularize the diaphragm
• Posterolateral (Bochdalek defect) in 70%, anterior (Morgagni) in 25–30%, central in 2–5%
• Main problem concerns pulmonary hypoplasia, which results in pulmonary hypertension.
  • Smaller lungs with fewer airway branches, fewer alveoli per terminal lung unit, and decreased surfactant production
  • Decreased pulmonary vascular surface area and smaller muscular arterioles with abnormal vasoreactivity results in pulmonary hypertension.
• Both ipsilateral and contralateral lungs are hypoplastic, worse on ipsilateral side.
• Degree of pulmonary hypoplasia and pulmonary hypertension determines illness severity both in acute and chronic settings.

Etiology

• Unknown
• Most cases occur sporadically.
• Experimental rat models suggest role of vitamin A deficiency in pathogenesis.

Commonly Associated Conditions

40–50% of cases associated with another type of congenital malformation

• Cardiac: 10–35%
• Genitourinary: 23%
• Gastrointestinal malformations: 14%
• Central nervous system abnormalities: 10%
  • Approximately 10% of cases with associated congenital anomalies have a syndrome.
  • Associated syndromes include Beckwith-Wiedemann and trisomies 13, 18, and 21.