Congenital diaphragmatic hernia natural history, complications and prognosis

CDH can present as small or large defects, both of which can be detected antenatally and present with varying symptoms depending on the size. Many neonates are initially stable for 24-48 hours, after which they experience acute respiratory distress. Some concerning complications include tracheobronchomalacia, pneumothorax, pulmonary hypertension, pulmonary infections and respiratory failure. Children often experience reduced exercise tolerance, stunted growth due to aversion to oral feeding, gastroesophageal reflux and anatomical chest deformities. Prognosis varies and is dependent on multiple factors. These include defect size, degree of pulmonary hypoplasia, development of pulmonary hypertension and other factors like birth weight and gestational age at birth. Due to ongoing advances in neonatal care, survival rate is now greater than 60%-80%.

CDH can be affected by a multitude of genetic syndromes and environmental factors. Approximately 2/3 cases of CDH can be detected antenatally and its presentation in the postnatal period largely depends upon the size of the defect. Smaller hernias often have a delayed presentation and are accompanied by mild respiratory symptoms and feeding difficulties. Comparatively, large defects present upon birth with decreased breath sounds, displaced heart sounds as well as abdominal changes such as a scaphoid abdomen.^[1]

In many neonates, there is an initial period of 24-48 hours of stability after which acute respiratory distress develops. Pulmonary hypoplasia is a common complication amongst almost all affected children.^[2] Major complications include:

• Tracheobronchomalacia
• Pneumothorax
• Pulmonary Hypertension
• Pulmonary infection; especially viral pneumonia and aspiration pneumonia
• Respiratory failure
• Increased incidence of congenital heart disease^[3]
• Reduced exercise tolerance
• Stunted growth due to aversion to oral feeding
• Gastroesophageal reflux^[4]
• Chest asymmetry, pectus excavatum and scoliosis following surgical repair of the chest wall
• Sensorineural hearing loss^[5]
• Uncommon complications: bowel obstruction, pectus excavatum, varying degrees of scoliosis, cryptorchidism, vesicoureteral reflux, and kidney stones^[6]

A diaphragmatic hernia is a very serious disorder. The outcome of surgery depends on how well the baby’s lungs have developed. Usually, the outlook is very good for infants who have enough lung tissue. Affected infants often require mechanical ventilation and oxygenation, followed by the use of diuretics after surgical correction. The use of oxygen and diuretics can be discontinued, often within the first two years of life.^[2] For children presenting with intermittent wheezing, bronchodilators are required. Some children require continued nutritional supplements. With advances in neonatal and surgical care, survival is now greater than 60%-80%. Ventilation strategies have also contributed to this increased survival rate. Although survival rates have increased, affected patients continue to have an increased risk of long term complications due to which continuous follow up in required.^[7]

Some important factors contributing to the prognosis include:^[8][9][10]

• Defect size
• Degree of pulmonary hypoplasia
• Development of pulmonary hypertension; this is often unresponsive to medical therapy
• Isolated or complex defect; complex defects are associated with higher mortality rates
• Presence of CVS malformations
• Birth weight
• Gestational age at birth
• Need for oxygenation

Proposed indicative methods include prenatal estimates of lung-to-head ratio, observed/expected-total fetal lung volume, as well as liver herniation percentage. Liver herniation is associated with a poor prognosis.