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.
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. Babies still need 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 children can 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.
Babies with CDH should be delivered in an 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 can be long term health issues related to breathing, feeding, growth and development problems.
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.
Amniocentesis may be advised for chromosome testing. Sonography is the best imaging tool, but is dependent on the experience and expertise of the operator. Magnetic resonance imaging (MRI) 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.
Careful and accurate prenatal assessment [level II sonogram, echocardiogram, sometimes magnetic resonance imaging (MRI)] may help us predict before birth the severity of the CDH. One of the most important issues is to make sure there are no other birth defects (like heart problems) that will affect outcome.
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 lower survival rate. The majority of the CDH patients we evaluate 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 better outcomes.
Fetuses who do not have liver herniated into the chest (liver down) usually have a less sever form of CDH and therefore a better prognosis. In our experience evaluating many hundreds of CDH patients, many of these patients do well after birth. We are, of course, delighted when we can predict a good outcome. These babies will still need specialized care after birth. We recommend these babies be delivered normally near term in a center with an intensive care nursery, pediatric surgery, and ECMO capability.
Fetuses with liver herniated into the chest and a lung-head ratio less than 1.0 have a more sever form of CDH. We can predict 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.
Although you can be given a prognosis on the severity of the CDH, until the baby for sure is born, there isn't a test to perform during pregnancy that can predict lung function. How your baby's lung's function will only be determined after they are born.
Mother tells the story of her experience of the diagnosis of CDH, care in the ICN, and the LIFE Clinic.
When Kristen Amen and Tony Garcia learned that their baby would be born with a condition called congenital diaphragmatic hernia (CDH), at first the news was devastating.