What is CDH?

What is a congenital diaphragmatic hernia?
Congenital Diaphragmatic Hernia "Congenital" means "born with." The diaphragm is the breathing muscle that separates the chest cavity and the abdominal cavity. The diaphragm develops when the fetus is about two months old. Congenital diaphragmatic hernia (CDH) is the absence of the diaphragm, or a hole in the diaphragm. This can occur on either the left or right side, but is most common on the left. The contents of the abdomen, including the stomach, intestines, liver and spleen, may go through the hole and into the chest. The contents prevent the normal development of the lung (pulmonary hypoplasia) on that side, and may affect the growth of the other lung. After birth the infant will have difficulty breathing if the lungs are not developed enough.
Normal chest cavity There are two types of diaphragmatic hernia: Bochdalek hernia: This type involves an opening on the back side of the diaphragm. The stomach, intestines and liver or spleen usually move up into the chest cavity. Morgagni hernia: This type is rare and involves an opening in the front of the diaphragm, just behind the breast bone. The liver or intestines may move up into the chest cavity.
What causes a diaphragmatic hernia?
As a fetus grows in its mother's uterus before birth, different organ systems are developing and maturing. The diaphragm forms between the 7th and 10th week of pregnancy. The esophagus (the tube that leads from the throat to the stomach), the stomach, and the intestines are also developing at this time. In a Bochdalek hernia, the diaphragm may not develop properly, or the intestine may become trapped in the chest cavity as the diaphragm is forming. At times, the tendon that should develop in the middle of the diaphragm does not develop properly. In both cases, normal development of the diaphragm and the digestive tract does not occur. Diaphragmatic hernia is a multifactorial condition, which means that "many factors," both genetic and environmental, are involved. It is thought that multiple genes from both parents, as well as a number of environmental factors that scientists do not yet fully understand, contribute to diaphragmatic hernia.
How often does a diaphragmatic hernia occur?
CDH occurs in about 1 in every 2,500 births. Bochdalek hernias make up about ninety percent of all cases.
Why is a diaphragmatic hernia of concern?
The lungs are developing at the same time as the diaphragm and the digestive system. A diaphragmatic hernia allows abdominal organs to move into the chest cavity, instead of remaining in the abdomen as they are developing. With the heart, lungs, and abdominal organs all taking up space in the chest cavity, the lungs do not have space to develop properly. This underdevelopment of the lungs is called pulmonary hypoplasia. A diaphragmatic hernia is a life-threatening illness. When the lungs do not develop properly during pregnancy, it can be difficult for the baby to breathe after birth. Healthy lungs have millions of small air sacs (alveoli), which resemble a balloon filled with air. With pulmonary hypoplasia: There are fewer air sacs than normal. The air sacs that are present are only able to partially fill with air. The air sacs deflate easily due to a lack of a lubricating fluid called surfactant. When these conditions are present, the baby is unable to take in enough oxygen to stay healthy. The intestines, when relocated in the chest, also may not develop properly, especially if they are not receiving enough blood supply while they are developing. A good blood supply is necessary for the intestines to develop correctly, and to be healthy and function properly. CDH is also of concern due to possible associated anomalies, which in some cases may include heart, genitourinary, gastrointestinal, central nervous system or chromosomal anomalies.