Congenital Diaphragmatic Hernia (CDH)

What is CDH?

Congenital diaphragmatic hernia (CDH) is a rare birth defect that occurs when a baby is born with a hole in their diaphragm. The diaphragm is a flat muscle located below the lungs that separates the chest from the abdomen. A hole in the diaphragm allows some or all of the abdominal organs (the stomach, liver, kidneys, intestines and spleen) to migrate into the baby’s chest cavity while the baby is still developing in the mother’s womb. The displacement of these organs is called herniation. The herniation of organs can happen on one or both sides of the chest cavity, depending on where the hole in the diaphragm is located. Most cases of CDH occur on the left side.

The abdominal organs cause crowding in the chest cavity, which affects the growth of the baby’s lungs and causes pulmonary hypoplasia (when a baby’s lungs do not grow to their normal size). Pulmonary hypoplasia affects the amount of air that can enter the lungs. Babies with this conditions have trouble getting enough oxygen from the air into their lungs and bloodstream. Pulmonary hypoplasia doesn’t become a problem until after the baby is born. While developing in the womb, the baby gets its oxygen from the mother’s placenta. However, after the baby is born, they must use their lungs to breathe on their own.

It is common for babies with CDH to develop pulmonary hypertension after birth as a result of their underdeveloped lungs. Pulmonary hypertension is when the blood pressure in the lungs is too high. This can cause oxygen levels in the baby’s blood to be too low, which can be a life-threatening complication. 

What causes CDH?

Doctors do not fully understand why babies develop CDH. 20% of CDH cases occur in babies with a genetic syndrome or chromosomal defect. Many of these babies will have other birth defects as well as CDH. 40% of babies with CDH will have at least one other birth defect.

What are the symptoms of CDH?

CDH is typically discovered during a routine prenatal ultrasound. The ultrasound may show abdominal organs in the developing fetus’ chest cavity, where the lungs should be.

After birth, a baby with CDH may show

• Problems breathing
• Abnormal chest movements
• Absent breath sounds on one side of the chest
• An “empty” seeming or appearing abdomen (belly area)
• Cyanosis (blue-tinted skin)

How is CDH diagnosed and evaluated?

After a prenatal ultrasound suggestive of CDH, you will be referred to a fetal care program. Our fetal care program at MassGeneral provides mothers and babies with a compassionate and dedicated team of experts to help guide families through the care process. Read more about the fetal care program at MassGeneral. 

Your doctor may use the following tests to diagnose CDH and gather more information about your baby’s condition:

• Fetal ultrasound. A detailed fetal ultrasound is used to examine the placement of the organs and size of the lungs.
• Fetal echocardiogram. An echocardiogram is used to determine if the baby’s heart developed normally and if the heart function is affected by CDH.
• In an amniocentesis, a sample of amniotic fluid is obtained from the mother’s abdomen and sent for genetic testing. This can reveal if the fetus has certain genetic abnormalities.
• Fetal MRI. An MRI scan focused on the fetus can show the size of the lugs and whether there are other birth defects.

All of these tests are performed while the baby is still developing in the womb. They are used to determine the severity of your baby’s CDH, which will help you and your doctor decide the right course of treatment.

When doctors evaluate the severity of a baby’s CDH, they may look at multiple diagnostic measurements:

• Liver herniation. CDH is considered to be more severe if a portion of the liver pushes through the hole in the diaphragm along with the other abdominal organs. In most fetuses with CDH, the liver is at least partially herniated (displaced into the chest cavity). When the liver is positioned further into the chest, the risk that the fetus will experience serious complications is higher. Fetuses without liver herniation have a better prognosis and usually do well after birth.
• Observed to expected lung volumes (O/E LV). These measurements are made by ultrasound or MRI and are used to compare the size of the fetus’ lungs to what a normally developing baby would have. The numbers are used to help determine the severity of the fetus’ pulmonary hypoplasia and can help indicate which babies are more likely to be very sick after birth from those who are likely to be less sick.  

How is CDH treated?

Many different factors will determine the course of treatment for your baby. You will be guided in the decision-making process by a multidisciplinary team of specialists experienced with treating CDH. They will answer any questions you have about treatments and potential outcomes for you and your baby.

How is CDH managed during pregnancy?

Babies with CDH require close monitoring while they grow in the mother’s womb. You will work with a team of doctors to develop a comprehensive delivery plan in case your baby needs intensive treatment after he or she is born.

Fetal surgery is a treatment option that can be performed during pregnancy. Fetuses with severe liver herniation and extremely poor lung growth may be candidates for a minimally invasive experimental procedure called fetoscopic tracheal occlusion or FETO. This specialized surgery is only offered in a few centers in the country, but not in New England.

How is CDH managed after delivery?

All babies with CDH will need specialized care after birth, which is why it is important that the baby is delivered in a hospital with extensive postnatal care capabilities. At Mass General for Children all babies born with CDH will be immediately attended to by a Neonatologist, a pediatrician who specializes in caring for newborn babies. If the baby needs help breathing, they will have a breathing tube placed in the delivery room.  The baby will be cared for in our Neonatal ICU (NICU) by a multidisciplinary team of neonatologists, surgeons, cardiologists, pediatric nurses, respiratory therapists, pharmacists and nutritionists. Together we work with the family to ensure that the baby receives the most up to date, safe and family centered care. The NICU is just 3 floor down from where mom delivers, so she can visit the baby while still in the hospital after delivery. There is also a bed in the baby’s room for a parent to stay once mom is discharged from the hospital.

Most babies with CDH are delivered vaginally. It is difficult to predict how much support a baby with CDH will need after birth. Depending on the severity of their condition, your newborn may need one or more of the following interventions:

• Nitric oxide is a gas that can help relax the blood vessels in your baby’s lungs and lower blood pressure. It is used to manage pulmonary hypertension.
• Ventilation can supply extra oxygen and help your baby breathe through a breathing tube inserted into the trachea (windpipe).
• ECMO (extracorporeal membrane oxygenation) is a specialized life support technique that uses a heart-lung bypass machine to circulate oxygen into the blood. ECMO is used when the baby’s lungs and/or heart are not functioning properly.

Surgery for CDH

Babies with CDH will need a congenital diaphragmatic hernia repair surgery to move their abdominal organs back to the correct location and close the hole in their diaphragm. The timing of the surgical repair will depend on your baby’s condition after birth. Your baby may have to spend days or weeks in the intensive care nursery before he or she is healthy enough for surgery.

During the procedure, your baby will be asleep under general anesthesia and feel no pain. A surgeon will make a cut below the baby’s ribcage and pull the abdominal organs down through the opening in the diaphragm and into the correct place. The hole in the diaphragm is then repaired in one of three ways:

• In a primary repair, the hole in the diaphragm is small enough that the muscle can be stitched back together.
• A patch repair is performed if the hole in the diaphragm is too large to be closed with stitches. A synthetic patch is sewn over the opening instead.
• In a muscle flap repair, the surgeon uses muscle tissue from the baby’s abdominal or back area to cover the opening in the diaphragm.

After surgery, the baby will be on a breathing machine and need to be monitored and cared for in the hospital for several weeks. After coming off the breathing machine, the baby may continue to need extra oxygen and medication. Most babies with CDH will also need to use a feeding tube for several weeks to receive the calories and nutrients they need to grow.

What are the Outcomes for Babies with CDH?

The prognosis for babies with CDH depends on many factors, including the severity of their CDH before treatment and whether or not there are other birth defects present. Many babies with CDH who receive proper treatment go on to meet all of their developmental milestones by kindergarten. Babies born with CDH will need to have frequent check-ups with their doctor throughout childhood to manage any complications they may develop. Complications of CDH may include:

• GERD (Gastroesophageal reflux disease). Many babies with CDH struggle with acid reflux after their feeding tube is removed. This may result in frequent spit-up and difficulty obtaining the nutrients that the baby needs to grow. When your baby is ready to come off of the feeding tube, our fetal care team will help you transition to breast feeding in a way that manages the baby’s acid reflux. Your baby may need to take anti-reflux medications to manage this condition. In severe cases, a doctor might recommend a surgery called a fundoplication to stop reflux.
• Bowel obstruction. Your baby’s intestines may form scar tissue as a result of being moved out of the chest and into the abdomen during CDH repair surgery. The scar tissue may cause kinking of the bowel (large intestine), which blocks the normal flow of digested material. This is called a bowel obstruction
• Respiratory problems and increased susceptibility to lung infections. Babies with CDH often have respiratory issues because of their undersized lungs. This can be solved with supplemental oxygen. Later on in life, the child may tire easily from exercise or develop asthma. Children born with CDH will also be at higher risk for respiratory infections like RSV (respiratory syncytial virus). This is a common cold virus that circulates in the winter and is not harmful to most people. However, it can be dangerous in the first few years of life for a child born with CDH. Your doctor may recommend that your baby receive special monthly injections during the winter months to protect him or her from RSV.
• Problems with skeletal development. Your baby may be at risk for skeletal problems as they grow older. Some children develop a curve in their spine called scoliosis because of the uneven size of their lungs or as a consequence of the surgery. Children may also develop a depression in their breastbone called pectus excavatum.
• Hearing loss. Babies that were intubated or put on ECMO to treat their CDH after birth are at higher risk for hearing problems. Doctors will perform hearing screening tests as your baby grows.
• Developmental delay. Babies who spend many weeks or months in the hospital after they are born are at risk for missing development milestones. It’s important to try to catch developmental delays as soon as possible.