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Congenital Diaphragmatic Hernia Learn More

• What is Congenital Diaphragmatic Hernia?
• What is the outcome for a fetus with CDH?
• How serious is my fetus’s diaphragmatic hernia?

What is Congenital Diaphragmatic Hernia?

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 is the outcome for a fetus with CDH?

There is a wide range of severity and outcomes for CDH. In the best cases, some infants do very well with routine treatment after birth. In the worst cases, some will not survive no matter how hard we try. And in the middle, some will live normally while others will have a difficult time and have to deal with some handicaps ranging from mild learning problems to breathing and growth problems. How the baby does after birth is determined by how well the lung grows before birth.

Fetuses on the best end of the spectrum have an excellent chance to lead a perfectly normal life. They do not require special prenatal management in terms of the timing or type of delivery, but should be delivered in a perinatal center with a Level III intensive care nursery with good neonatal and pediatric surgery support. The place of delivery is very important because transporting these babies after birth can be dangerous for the infant. Many babies still have to have the defect repaired after birth and will be in the intensive care nursery for several weeks. Even though the lung isn’t of normal size at birth, it has the capacity to grow and adapt for many years, so these kids will lead normal active lives without restriction.

On the other end of the spectrum, babies with severe CDH and very small lungs are guaranteed to have a difficult struggle after birth, and some will not survive. These babies require very skilled intensive care to stay alive—things like high-frequency or oscillatory ventilation, inhaled nitric oxide and, in some cases, extracorporeal membrane oxygenation (ECMO). ECMO provides temporary support for lung failure by circulating the baby’s blood through a heart-lung type machine. It can be life-saving, but can be used for only limited time before complications become excessive.

These babies must be delivered in a very experienced tertiary perinatal center with ECMO capability. The surgery to repair diaphragmatic hernia after birth is not an extreme emergency and is usually performed when the baby has stabilized in the first week of life. After repair, these babies will need intensive support for many weeks or even months. Even when the CDH is severe, greater than 70% of affected babies can be saved with intensive support. However, there will be long term health issues related to breathing, feeding, growth and development problems.

Most fetuses with CDH fall between these extremes of severity.

How serious is my fetus’s diaphragmatic hernia?

In order to determine the severity of your fetus's condition it is important to gather information from a variety of tests and determine if there are any additional problems. These tests along with expert guidance are important for you to make the best decision about the proper treatment.

This includes:

1. The type of defect—distinguishing it from other similar appearing problems.
2. The severity of the defect—is your fetus’s defect mild or severe.
3. Associated defects—is there another problem or a cluster of problems (syndrome).

Amniocentesis may be necessary for chromosome testing. Sonography is the best imaging tool, but is dependent on the experience and expertise of the operator. Magnetic resonance imaging may be necessary in some cases. Many problems are first detected during routine screening procedures performed in your doctor’s office (amniocentesis, maternal serum screening, routine sonography). However a through assessment usually requires a tertiary perinatal/neonatal center with experience managing complex and rare fetal problems. We can work with your doctor to find a center convenient for you.

Fortunately, we can now predict before birth how good or bad your fetus’s CDH is. Careful and accurate prenatal assessment [level II sonogram, echocardiogram, sometimes magnetic resonance imaging (MRI)] is critical for your decision-making and planning. One of the most important issues is to make sure there are no other birth defects (like heart problems) that will affect outcome.

Major Factors in Determining Severity

When CDH is the only problem, we have learned that severity and, thus, outcome is determined by two factors: 1) liver position, and 2) lung-to-head ratio or LHR. Liver position refers to whether or not any portion of the liver has herniated, or gone up into the chest of the fetus. Fetuses with the liver up in the chest have a more severe form of CDH and a low survival rate. About 75% of all CDH patients have some portion of the liver herniated into the chest. The lung-to-head ratio, or LHR, is a numeric estimate of the size of the fetal lungs, based on measurement of the amount of visible lung. High LHR values are associated with a good outcome.

Fetuses on the best end of the spectrum do not have liver herniated into the chest (liver down) and have a high lung-to-head ratio LHR greater than 1.4, indicating a relatively large lung. In our experience evaluating many hundreds of CDH patients, about 25% are on the best end of the spectrum (liver down and/or high LHR greater than 1.4), and they all do well after birth. We are, of course, delighted when we can confidently predict a good outcome. We recommend these babies be delivered normally near term in a center with a very good intensive care nursery and good pediatric surgery.

Fetuses with liver herniated into the chest and a lung-head ratio less than 1.0 are on the worst end of the spectrum. We can be sure that they will have a very difficult time after birth. Most can be helped with very high level intensive care, including ECMO. However, the very intensive care required for the most severe cases can lead to complications and long-term problems, including breathing and feeding difficulties for many years. In our experience, about 25% of fetuses have this severe form of CDH, and about 70% of these survive with very intensive management, but often with some handicap.

About half of all fetuses with CDH are neither very good nor very bad, but are somewhere in the middle of this spectrum. With good intensive care and surgery at an experienced medical center, most (more than 90%) will survive and do quite well.