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Congenital Diaphragmatic Hernia Repair
Herniation of the bowel through the diaphragm into the chest

Congenital diaphragmatic hernia is the herniation of the bowel through the diaphragm into the chest. There is usually a defect in the development of the left side of the diaphragm. It occurs in approximately 1 in 2500 newborns. The herniation occurs in the 8-10th week of gestation.

Anatomy

  • The diaphragm is the main muscle of respiration (breathing)
  • The diaphragm is a sheet of tissue composed of muscle and fascia (layer of connective tissue) that separates the thoracic (chest) cavity from the abdominal cavity
  • It is composed of three muscles parts about the rim that lead to a central tendinous portion (Figure 1)
  • The muscle parts are:
    1. The sternal portion that attaches to the breastbone area
    2. The costal (rib) portion that attaches along the ribs
    3. The lumbar portion that attaches along the back
  • The tissue formed by the fusion of the various parts of the diaphragm is called the pleuroperitoneal membrane
  • The are three openings in the diaphragm that allow passage of:
    1. The inferior vena cava
    2. The esophagus
    3. The aorta
  • The diaphragm is covered on both sides by a membranous layer of fascia. The transversalis fascia covers the abdominal side (under side), and the endothoracic fascia covers the thoracic side (top side)
  • The phrenic nerves (one on each side) are the only nerves that control the muscles of the diaphragm
  • The arteries come from both sides of the diaphragm
Figure 1 - Anatomy of the diaphragm as seen from below. © C. McKee

Pathology

  • Diaphragmatic hernias occur because of failure of normal formation of the various parts of the diaphragm
    1. Morgagni hernia occurs where the sternal and costal muscle portions come together (Figure 2)
    2. Bochdalek hernia involves failure to close the left pleuroperitoneal membrane (Fig. 2). The Bochdalek hernia is the more common of the hernias
  • The herniated bowel is covered with a peritoneal covering and occupies the left chest preventing normal lung development (Figure 3)
    1. The greater the amount of herniated bowel, the greater is the lung compression and underdevelopment (hypoplasia)
    2. The major bronchi (tubes going into the lungs) are reduced in size with decreased alveolar surface (cell membrane through which oxygen passes into the lung capillaries) and abnormal blood vessels. Associated anomalies are common
    3. These infants present with varying degrees of respiratory distress. The degree of respiratory distress is a major factor in survival with underdevelopment of the lung a critical issue
Figure 2 - Sites of common diaphragmatic hernias.© C. McKeeFigure 3 - Bochdalek diaphragmatic hernia with bowel in left chest with compression of the lung. © C. McKee

History and Exam

  • These infants present with respiratory distress at birth
  • Examination reveals the absent breath sounds from the left chest

Tests

  • A chest X-ray will show bowel in the left chest with a hypoplastic left lung. Additional imaging studies are usually not necessary
  • Blood gas studies are performed to determine the level of oxygen
  • This defect may be diagnosed with prenatal ultrasound examinations as early as fifteen weeks gestation

Surgical Indications

  • The defect will have to be repaired at some time. Emergency surgery, however, is not as common today because of new ways to treat these situations
    1. As a temporary measure blood can be oxygenated using an extracorporeal membrane oxygenator, a form of cardiopulmonary bypass that oxygenates the infants blood. Blood is withdrawn from the venous side of the circulation and passed into the membrane oxygenator and then returned to infant on the arterial side
    2. Improved respiratory ventilators and ventilator techniques using permissive hypercapnia (allows carbon dioxide to build up in the blood stream) have improved infant survival
  • Loss of blood supply to the herniated bowel is rare

Surgery

  • Surgery is undertaken as soon as the child is felt to be stable enough to tolerate an operation
  • The operation is performed under general anesthesia with extensive monitoring in a warmed operating room
  • An incision is usually made below the left ribs
  • The abdominal contents are removed from the thoracic cavity and inspected for any other anomalies (abnormalities)
  • The hernia sac is separated from the bowel and removed
  • The compressed hypoplastic left lung is gently inflated
  • The defect in the diaphragm is closed by bringing the infants tissues together or by using a synthetic material (Figures 4 and 5)
  • A chest tube is placed in the left chest to remove air from between the lung and chest wall
  • The abdominal cavity will usually accommodate the herniated bowel without causing compression within the abdomen
  • The incision is closed and the infant returned to the Pediatric Intensive Care Unit
Figure 4 - After the hernia is placed back in the abdominal cavity, sutures are placed in the edges of the hernia.(as seen from above through the thoracotomy incision). © C. McKee Figure 5 - The sutures are brought together to close the hole in the diaphragm. © C. McKee

Complications

The complications associated with any major operation may occur including:

  • Bleeding
  • Respiratory distress
  • Hypothermia (low body temperature)
  • Low urine output
  • Infection
  • Bowel obstruction

Post Operative Care

  • The child is cared for in the Pediatric Intensive Care Unit
  • The infant requires ventilator support. The infant is monitored to ensure adequate breathing
  • Temperature is monitored
  • Urine output is monitored
  • Intravenous fluids are given and monitored
  • A tube is placed through the nose into the stomach to decompress the stomach
  • Antibiotics are usually given
  • Prolonged intensive care may be required

Follow Up

  • These children may be hospitalized for long periods and require special follow up
  • The goal is to have a healthy baby able to eat, urinate, and eliminate stool at the time of discharge without need for respiratory or special nutritional support
  • Follow up will be determined by the complexity of the diaphragmatic hernia