Congenital Diaphragmatic Hernia

What is congenital diaphragmatic hernia?

Congenital diaphragmatic hernia (CDH) is a birth defect that occurs during fetal development. It means that the diaphragm — the muscle barrier that separates a fetus’s abdominal cavity from its chest cavity — is not fully formed or strong enough to keep the two cavities separate. That means organs can pass between them. When an organ passes through a muscle barrier, it’s called a hernia.

When a diaphragmatic hernia occurs during fetal development, it affects the way the fetus’s body forms. Its abdominal organs — the stomach, intestines, liver, gallbladder, pancreas and spleen – can shift upward into the chest cavity while everything is still developing. When this happens, the extra organs in the fetus’s chest can end up crowding its lungs and prevent them from growing normally.

How serious is congenital diaphragmatic hernia?

CDH can be very serious. Babies born with this condition tend to have small, underdeveloped lungs with weak blood vessels. This can cause low blood oxygen levels and breathing difficulties at birth. They will also have high blood pressure in their lungs, which puts stress on their heart. These babies will need critical care at birth to stabilize their condition. They may need supportive care throughout their lives.

How common is congenital diaphragmatic hernia?

Congenital diaphragmatic hernia affects 1 in 2,500 - 3,500 live births. About half of these are isolated anomalies that occur without any other conditions. The other half occur together with other genetic disorders, such as congenital heart defects and Down syndrome. If you have prenatal care during your pregnancy, your doctor will be able to see these conditions and prepare for them before you give birth.

What causes congenital diaphragmatic hernia?

Congenital diaphragmatic hernia (CDH) is a birth irregularity. Its exact cause is unknown, but it may be related to:

• Genetics.
• Harmful environmental exposure during pregnancy.
• Fetal malnutrition.

What are the signs and symptoms of congenital diaphragmatic hernia?

Babies born with CDH may present with:

• Abnormal breathing.
• Rapid heart rate.
• Blue discoloration from lack of oxygen (cyanosis).
• Weak breath sounds (usually on one side).
• Bowel sounds in the chest.
• Concave abdomen and barrel chest.
• Abdominal pain.
• Constipation due to bowel obstruction.

What are the potential complications of CDH?

Most infants born with congenital diaphragmatic hernia will have small and underdeveloped lungs (pulmonary hypoplasia). This can cause a variety of difficulties, including:

• Hypoxemia (low blood oxygen levels), which affects the functioning of all of the organs, especially the brain and heart. If it’s severe or persistent, it can cause long-term damage.
• Pulmonary hypertension (high blood pressure in the arteries of the lungs). This condition strains the right ventricle of the heart and can lead to heart failure.
• Lung infections. Underdeveloped lungs are more vulnerable to infection, such as pneumonia. This can be a lifelong problem, even after the hernia has been repaired.

Infants with CDH are also prone to:

• Feeding difficulties. This might result from compression of the digestive organs and symptoms of gastroesophageal reflux, or simply from difficult birth circumstances requiring a lot of medical intervention. Babies may require long-term tube feeding and have “failure to thrive” and growth problems. Some may require surgery to treat GERD.
• Developmental delays. Due to both nutritional and oxygen deficiencies, some babies may have developmental delays. They may require physical, speech or occupational therapy over time.
• Sensorineural hearing loss. About 25% of infants with CDH develop progressive hearing loss. It’s unclear whether this is a complication of the condition, the treatments (such as high-frequency mechanical ventilation and medications) or both.

How is congenital diaphragmatic hernia diagnosed?

Congenital diaphragmatic hernia is often discovered during a routine prenatal ultrasound. It will also show up on an amniocentesis, the prenatal test that you can have to diagnose genetic disorders during the second trimester. After discovery, your healthcare provider will follow up with a fetal MRI to see the hernia more clearly. They’ll take a fetal echocardiogram to find out whether the heart is affected.

Sometimes CDH isn’t discovered until after your baby is born. Your delivery team may notice signs of respiratory distress or anatomical signs, such as an asymmetrical chest or a barrel chest with a small or concave abdomen. They will follow up with a chest X-ray and an echocardiogram. They may want to take a blood sample to test your baby’s blood oxygen levels and to look for other genetic anomalies.

Rarely, babies born with CDH have no noticeable symptoms. If the hernia is small and causes no significant symptoms, it may not be discovered until later in childhood, or even in adulthood.

How is congenital diaphragmatic hernia treated?

Ultimately, your baby will need surgery to repair the hernia. But before that, they will need some more immediate therapies to prevent or manage other organ damage caused by the condition.

Prenatal treatment

Medical care for congenital diaphragmatic hernia begins as soon as it’s diagnosed.

Surveillance

CDH that’s discovered during pregnancy will be monitored closely. Doctors will look for congenital issues in other organ systems that can be part of a more complex disease. They will also watch for signs of premature labor and decide whether they need to induce your labor early for the sake of the fetus. You will need to have access to a hospital that has a specialized team of providers who treat CDH.

Fetoscopy

In some cases, your healthcare team may be able to help your fetus before birth. Fetoscopic tracheal occlusion (FETO) is a surgical procedure that can help improve the size and function of the fetus’s lungs while it’s still growing. It’s done by fetoscopy, a minimally-invasive surgery that uses a tiny lighted camera called a fetoscope to view the fetus through small incisions through your skin and into your uterus.

FETO allows a doctor to place a balloon in the fetus’s trachea (breathing tube). This allows the amniotic fluid they breathe to build up in its lungs behind the balloon, causing its lungs to expand. This expansion appears to improve the growth and function of the lungs and reverse some of the damage caused by CDH. After a few weeks, a second fetoscopic procedure removes the balloon.

Neonatal treatment

Babies who are born with CDH usually require immediate intensive care by a specialized team.

Oxygen support

Babies with pulmonary hypoplasia (underdeveloped lungs) — which is most of them — will require oxygen support first. For some, this means a breathing tube attached to a mechanical ventilator. Others may require a more aggressive life support called extracorporeal membrane oxygenation (ECMO). This is a way of bypassing the underdeveloped lungs and sometimes the heart. ECMO draws blood from an artery or vein and oxygenates the blood in a machine before sending it back into your baby’s circulation.

Surgery

Your baby will remain in intensive care until your healthcare team determines that it’s safe to consider surgery. This usually means that pulmonary hypertension has improved and ECMO is no longer needed. For the surgery, a pediatric anesthesiologist will put your baby to sleep with anesthesia. A pediatric surgeon will operate on your baby to move their organs back into place and repair the defect in their diaphragm.

Recovery

As your baby recovers from surgery, they will begin to come off oxygen support. They will have to be fed through a tube until the breathing tube is removed. After that, speech and lactation specialists can work with you and your baby to begin mouth feeding. Some babies take longer than others to transition from oxygen support and tube feeding. Your healthcare team will work with you for as long as necessary.

What’s the prognosis for children born with congenital diaphragmatic hernia?

The reported survival rate for babies diagnosed with CDH is between 70% and 90%. These babies are born critically ill, but for those who make it through the tense early days of their condition, the outlook gets better. Some children may have some long-term complications, but still live long and full lives. Continuing advances in medicine improve the odds of both short-term survival and long-term health.

The longer-term prognosis depends on how severe your baby’s condition is at birth. This is related to the size of the hernia, what organs are involved and any other conditions. Babies who require breathing or feeding support for longer have a higher risk of ongoing complications, including chronic lung disease, growth failure, hearing loss and developmental delays. These children will be closely monitored through their early life.

What is the difference between a diaphragmatic hernia vs. a hiatal hernia?

A hiatal hernia is a type of diaphragmatic hernia, but it’s not congenital, which means it’s not present at birth. It happens during the course of your lifetime. It’s very common, and far less serious than CDH. A hiatal hernia comes through an opening in your diaphragm that already existed — the place where your esophagus passes through from your chest into your abdomen. It can occur in children and adults.

A hiatal hernia occurs when abdominal pressure from things like coughing or heavy lifting causes your diaphragm to weaken. This weakening affects the existing opening in your diaphragm where your esophagus passes through. It allows the bottom part of your esophagus and the top part of your stomach to slip up partway through the opening. It causes mild symptoms, and may not need to be repaired.