What is a Congenital Diaphragmatic Hernia / CDH?                       The wide, flat muscle that separates the chest and abdominal cavities is called the diaphragm. The diaphragm forms when a fetus is at 8 weeks’ gestation. When it does not form completely, a defect, called a congenital diaphragmatic hernia (CDH), is created. This is a hole in the muscle between the chest and the abdomen.

The majority of CDHs occur on the left side. The hole allows the contents of the abdomen (stomach, intestine, liver, spleen, and kidneys) to go up into the fetal chest. The herniation of these abdominal organs into the chest occupies that space and prevents the lungs from growing to normal size. The growth of both lungs can be affected. This is called pulmonary hypoplasia

While in the uterus, a fetus does not need its lungs to breathe, because the placenta performs this function. However, if the lungs are too small after the baby is born, the baby will not be able to provide itself with enough oxygen to survive.

What Causes Congenital Diaphragmatic Hernia?
The cause of Congenital Diaphragmatic Hernia is thought to be failure of the diaphragm to develop at nine to 10 weeks of gestation. When closure does not occur, the intestinal organs may herniate into the chest cavity through the defect in the diaphragm. What causes the failure of the diaphragm to close is unknown.

What is the Incidence of Congenital Diaphragmatic Hernia?
The incidence of Congenital Diaphragmatic Hernia is estimated at one in 2,200 births. Survival rate depends, in large part, on the delivery at or the immediate transfer to a tertiary-care hospital where the newborn can be treated promptly by a staff skilled in Congenital Diaphragmatic Hernia care.

How is Congenital Diaphragmatic Hernia Diagnosed?
An ultrasound can detect characteristics of Congenital Diaphragmatic Hernia. Physicians, performing ultrasound, closely examine the entire chest and abdominal area to look for what can be very subtle signs of Congenital Diaphragmatic Hernia. This diagnosis can also be aided by fetal MRI.

Schematic drawing showing a severe left-sided congenital diaphragmatic hernia with liver and bowel herniation in to the fetal chest.

Close-up of schematic drawing showing a severe left-sided congenital diaphragmatic hernia with liver and bowel herniation into the fetal chest.

This ultrasound of a congenital diaphragmatic hernia case shows a cross-section through the fetal chest, including severe mediastinal shift and posterior stomach. The Level II ultrasound provides a lung-to-head ratio to help predict those fetuses most severely affected with congenital diaphragmatic hernia.