• Clinical science

Congenital diaphragmatic hernias

Summary

A diaphragmatic hernia is the protrusion of intra-abdominal contents through an abnormal opening in the diaphragm. Congenital diaphragmatic hernias (CDH) are a common developmental defect, resulting from an incomplete fusion of embryonic components of the diaphragm. Left-sided postero-lateral diaphragmatic defects (Bochdalek hernias) are the most common, followed by anterior defects (Morgagni hernias). About 50% of babies with CDH have additional congenital malformations. CDH are often diagnosed prenatally on routine antenatal ultrasound. Neonates with CDH present postnatally with respiratory distress and a characteristic absence of breath sounds in the ipsilateral chest. The respiratory distress is due to severe pulmonary hypoplasia, persistent pulmonary hypertension of the newborn (PPHN), and poor surfactant production, all of which are typical characteristics of CDH. Postnatal diagnosis is confirmed on a chest x-ray which reveals abdominal contents in the thorax. Neonates with CDH should be medically stabilized (mechanical ventilation, inotropic support, gastric decompression) before surgical repair, which is then done within the first week of life. Also see our learning card “Acquired diaphragmatic hernias”.

Epidemiology

  • Incidence: one in 3000 live births[1]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

  • Impaired development and/or fusion of embryonic structures (pleuroperitoneal membrane) → defect in the diaphragm persists during fetal development → displacement of abdominal contents into the pleural cavity → compression of lung tissue pulmonary hypoplasia
  • Types:
    • Failure of fusion of the septum transversum postero-laterally with the pleuroperitoneal membranesBochdalek hernia.
      • Most common CDH, accounting for 90% of cases.
      • Postero-lateral (lumbocostal) CDH (85% are left-sided)
    • Failure of fusion of the septum transversum anteriorly with the sternum and ribsMorgagni hernia (Morgagni-Larrey hernia)
      • Rare: < 5% of CDH
      • Anterior (sternocostal/parasternal) CDH (90% are right-sided)[2]
      • Infants with Morgagni hernia often present late.

Because the liver protects the right hemidiaphragm, diaphragmatic hernias most commonly occur on the left side!

References:[3][4][5][6]

Clinical features

  • Presentation depends on the degree of pulmonary hypoplasia and pulmonary hypertension
  • Respiratory distress (e.g., nasal flaring, tachypnea, cyanosis, intercostal retractions, grunting)
  • Barrel-shaped chest, scaphoid abdomen, and auscultation of bowel sounds in the chest[2]
  • Absent breath sounds on the ipsilateral side
  • Mediastinal shift: shift of heart sounds/apex beat to the right side
  • Possible syndromic dysmorphism (e.g., craniofacial, spinal dysraphism, cardiac)

References:[4][7]

Diagnostics

  • Antenatal ultrasound[8]: most cases are diagnosed on routine antenatal ultrasound[5]
    • Fluid-filled stomach/bowel seen in the thorax
    • Peristalsis may also be noted in the chest, confirming the diagnosis.
    • Esophageal compression can cause polyhydramnios
    • Hydrops fetalis may also be seen in severe cases
  • Chest x-ray[4]
    • Abdominal contents, air/fluid-filled bowel, and poorly aerated lung in the ipsilateral hemithorax
    • Mediastinal shift to the right + compression of the contralateral lung
    • In doubtful cases, a naso-gastric tube is inserted and a chest radiograph is taken: the feeding tube will be seen in the thorax.
    • In right-sided CDH: the liver appears as an intrathoracic soft tissue mass + absence of the normal intra-abdominal liver shadow

Avoid pleurocentesis in a suspected diaphragmatic hernia because of the risk of bowel perforation, which is suggested by bile in the chest tube!

Differential diagnoses

  • Prenatal CDH
    • Congenital diaphragmatic eventration
    • Bronchogenic cysts;
      • Clinical features
        • Usually asymptomatic
        • In some cases, failure to drain can cause airway compression with significant respiratory distress or recurrent respiratory tract infections
      • Diagnostics
        • Chest x-ray: discrete, round, and sharply defined fluid-filled densities
      Pathogenesis: abnormal budding of the ventral foregut → dilation of the terminal or large bronchi → unilateral or bilateral unilocular cysts
    • Congenital cystic adenomatoid malformation (CCAM)
  • Postnatal CDH

References:[4]

The differential diagnoses listed here are not exhaustive.

Treatment

Complications

  • Bowel complications: obstruction, strangulation, incarceration, ileus, ulceration, perforation

References:[1]

We list the most important complications. The selection is not exhaustive.