What is a congenital diaphragmatic hernia (CDH)?

CDH stands for congenital diaphragmatic hernia. Simply put, it is a hole in the diaphragm. At some point early in fetal development, the diaphragm does not completely form. It is believed that this occurs between 4 and 10 weeks gestation. The malformation can be large or small. There is no definitive answer on why this happens although there is a study suggesting that it has something to do with the fetus’ lack of ability to absorb vitamin A.

CDH occurs in approximately one out of every 2000-3000 births. That number can be misleading because it does not take into account those who choose to terminate their pregnancies or pregnancies that end in miscarriage.

At the same time the diaphragm is forming, other vital organs are also developing. Because of the hole in the diaphragm, abdominal organs can and do migrate into the chest cavity. Depending on the size of the hole, the entire abdominal contents can be located in the chest or just a small loop of intestine, part of the stomach, etc. There is a wide variety in the severity of CDH from person to person.

Because the organs that are normally in the abdomen are in the chest cavity, lung development is impaired. Again, depending on the severity of the defect, lung development can be severely limited or almost normal. The air sacs on the surface of the lungs (alveoli) can also be affected. These sacs inflate and help rid the body of carbon dioxide.

Another big concern with CDH is PPHN, persistent pulmonary hypertension. Information on PPHN can be found here.

With modern technology, many cases of CDH can be diagnosed at a routine ultrasound around the 20th week of pregnancy. The more severe the defect and the better the individual performing the ultrasound, the earlier the diagnosis can be made. However, there are cases not diagnosed until birth or even later in life.