• Herniation of abdominal contents into the thoracic cavity through an opening in the diaphragm
• Two types of congenital diaphragmatic hernias
  • Bochdalek hernia (posterolateral location)
  • Morgagni hernia (retrosternal location)

• Diaphragm forms between 7 to 10 weeks of gestation
• Diaphragm is composed of two parts:
  • Pleuroperitoneal folds attach to the chest wall, develop a muscular lining and become the lateral and dorsal portions of the diaphragm
  • Septum transversum, which becomes the central tendon of the diaphragm
• Anything that interferes with the formation of the diaphragm allows an abdominal hernia to develop
• Bochdalek hernia develops when:
  • Midgut returns to the abdominal cavity prematurely or diaphragmatic development is delayed
  • Bowel is trapped in the thoracic cavity, preventing the pleuroperitoneal folds from connecting with the thoracic wall
    • This allows a communication to exist between the thoracic and abdominal cavities
• Morgagni hernia develops when:
  • A defect develops in the septum transversum

• Bochdalek hernia
  • Usually occurs on the left side (left-sided pleuroperitoneal folds close later than the right)
  • Bowel in the thoracic cavity
  • Bilateral lung hypoplasia (ipsilateral lung hypoplasia worse than contralateral side)
• Morgagni hernia
  • Usually occurs on the right side (left-sided defects are covered by the heart)
  • Hernia can contain: liver, bowel, and omentum
  • Less lung hypoplasia seen than with Bochdalek hernias

• Bochdalek hernia
  • Accounts for 90% of cases of congenital diaphragmatic hernias
  • Incidence: in 1/2200 to 1/5000 live births
  • 80% to 90% of cases on the left side (bilateral cases are rare)
  • Slightly more common in males
    • 40% of cases associated with some type of congenital malformation
    • 5% to 16% of cases with chromosomal abnormality
    • 18% associated with a congenital heart disease
• Morgagni hernia
  • Accounts for 2% of all diaphragmatic hernias more common in females

• Estimated 2% recurrence rate in first degree relatives

• Bochdalek hernia
  • Pulmonary hypertension
  • Persistent fetal circulation with right to left
  • Shunting
  • Pulmonary insufficiency
  • Death
• Morgagni hernia
  • 10% incidence of strangulation of the bowel if not repaired

• Pulmonary cysts
• Cystic adenomatoid malformation
• Pneumatocele
• Congenital lobar emphysema
• Pulmonary sequestration
• Eventration of the diaphragm
• Hiatal hernia
• Laryngotracheal obstruction
• Atelectasis
• Pneumothorax
• Anterior mediastinal mass
• Pneumonia
• Pleural effusion

• Dextrocardia
• Congenital heart disease

Question: Bochdalek hernia?
Significance: Presents at birth; patient frequently presents in severe cardiopulmonary distress.

Question: Morgagni hernia?
Significance: Usually asymptomatic. If symptomatic, usually presents later in life. May have complaints of: vague abdominal discomfort, vomiting, failure to thrive, chest pain, dyspnea, cough, and recurrent respiratory infections.

Finding: Bochdalek hernia
Significance:

Finding: Morgagni hernia
Significance: Examination may be normal

Test: Arterial blood gas
Significance:

Test: Chest radiograph
Significance:

Test: Fetal ultrasound
Significance: Abdominal viscera in the thoracic cavity; polyhydramnios

• Bochdalek hernia
  • Resuscitation of the patient
  • Stabilization of the patient:
    • Oxygenation
    • Correction of acidosis
    • Normalization of blood pressure
    • Decompression of the intrathoracic bowel (placement of a nasogastric tube to low suction allows the bowel to decompress, thus letting the ipsilateral hypoplastic lung expand)
  • Surgical repair of the defect:
    • Decreased morbidity and mortality if the patient can be stabilized prior to surgical repair
  • Post-operative management
  • ECMO (extracorporeal membrane oxygenation)
    • May prove useful in the peri-operative management:
    • Pre-operative: for patient stabilization
    • Post-operative: to allow the lungs to fully expand after the compressing intrathoracic bowel has been removed
  • If the diagnosis of a Bochdalek hernia is made early enough in gestation (i.e., 24–28 weeks gestation), fetal surgery to repair the defect may be considered
• Morgagni hernia
  • Surgical repair is indicated, even if the patient is asymptomatic, due to the high rate of strangulation of the intrathoracic bowel (10%)

• The development of pulmonary hypertension in the post-operative period
• Rapid development of hypoxia is associated with the development of a pneumothorax

• Bochdalek hernias:
  • Dependent on the degree of pulmonary hyperplasia and pulmonary hypertension:
    • If not surgically repaired: 100% mortality
    • If patient survives the peri-operative period: 33% to 65% survival
  • Poor prognostic factors:
    • Polyhydramnios in utero
    • Fetal stomach in the thoracic cavity
    • Early presentation (i.e., presenting in the first 6 hours versus after 24 hours)
    • Persistent elevated pCO₂ and decreased pO₂
• Morgagni hernias: excellent

• Not being able to stabilize the patient (suggestive of severe pulmonary hypoplasia and/or pulmonary hypertension)
• Delay in getting the patient to an appropriate medical center
• Not recognizing other congenital malformations or chromosomal abnormalities that may affect the patient’s ultimate outcome or which would represent a contraindication for surgical repair (i.e., Trisomy 18)

• Not considering the diagnosis when abnormalities seen on chest radiograph

Q: What is the long-term pulmonary function in survivors of Bochdalek hernias?
A: Dependent on the degree of pulmonary hypoplasia; pulmonary function testing shows evidence of both obstructive and/or restrictive lung disease. Decreased perfusion on the affected side.

Q: What long-term problems can be seen in survivors of Bochdalek hernias?
A: Dependent on the degree of pulmonary hypoplasia; recurrent respiratory infections of the hypoplastic lungs.

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