Congenital diaphragmatic hernia pathophysiology

Congenital diaphragmatic hernia occurs when the development of the diaphragm during the 12th week of gestation is inadequate leading to a discontinuity. Such a defect leads to herniation into the thoracic cavity and resultant lung hypoplasia. Affected children often experience decreased lung volume, reduced blood circulation through the lungs and resultant respiratory complications.

To best understand the underlying cause of CDH, there are some anatomical aspects that should be explained. The main components of the diaphragms development are completed by the 12th week of gestation, and primarily include the septum transversum and pleuroperitoneal membranes. In the event of any disturbance to this process, there may be some discontinuity leading to weakness of the wall and the potential for a hernia to develop. Once herniation occurs into the thoracic cavity, normal pulmonary development is often compromised resulting in lung hypoplasia and a marked decrease in the airways of terminal bronchioles and alveoli.^[1] Pulmonary hypertension is a restriction of blood flow through the lungs thought to be caused by defects in the lung.

It involves three major defects:

• A failure of the diaphragm to completely close during development
• Herniation of the abdominal contents into the chest
• Pulmonary hypoplasia or decreased lung volume is directly related to the abdominal organs presence in the chest cavity which causes the lungs to be severely undersized, especially on the side of the hernia