Congenital diaphragmatic hernia (CDH)
Congenital diaphragmatic hernia (CDH) is a rare birth defect involving a 'rupture' (hernia) in the diaphragm. The diaphragm is a flat muscle that separates the abdominal cavity from the chest. It is formed during the tenth week of pregnancy. The diaphragm also helps with breathing. The hernia may cause part of the abdominal contents to enter the thoracic cavity. This leads to underdevelopment of the lungs (lung hypoplasia) and displacement of the heart to the other side of the body.
The defect usually occurs on the left side (80%), and sometimes on the right. On the right side it does not always cause problems because the liver on the right side of the abdomen can close the defect. If part of the liver ends up in the thoracic cavity, it does cause symptoms. With a left-sided defect, the stomach, intestines or spleen can end up in the thoracic cavity. The defect in the diaphragm causes the contents of the abdomen to enter the thoracic cavity and to displace the lung. This leads to underdevelopment of the lung, with less branching of the respiratory tract and an abnormal formation of blood vessels. This can lead to high pressure in the blood vessels of the lungs (pulmonary hypertension). The degree of underdevelopment of the lungs and the severity of the high blood pressure in the lungs determine the course of this disease and its long-term consequences.
The left-hand drawing shows the healthy situation in which the diaphragm is closed. In the middle drawing the diaphragm on the left has a rupture. The right-hand drawing shows that the intestines enter the thoracic cavity through the rupture, leaving the lungs with less space to develop. The life expectancy of children with congenital diaphragmatic depends largely on the location of the defect and the degree of development of the lungs.