Congenital Diaphragmatic Hernia
What is congenital diaphragmatic hernia?
An infant with a congenital diaphragmatic hernia.
Congenital diaphragmatic (dye-ah-fra-mat-ick) hernia is an opening in the diaphragm, which is the muscle separating the chest from the abdomen (see illustration at right). This hole allows the contents that would normally be in the abdominal cavity to push up into the chest cavity. The lungs may be underdeveloped (hypoplastic) because they lack the space to grow. CDH can have an affect on both lungs even though the defect is only on one side. If the amount of abdominal contents herniated into the chest is significant enough, the heart and other lung will be pushed out of the midline. This shift will reduce the amount of space for the other lung to grow, also. The hole occurs 90 percent of the time on the left side. The defect in the diaphragm can range from being a very small hole with only a loop of bowel protruding through it, to a severe defect in which no diaphragm or only minimal diaphragm is present. If the hole is large enough to allow the liver and intestines into the chest, the repair may require a prosthetic patch and has a poorer prognosis. The other extreme is a small hole with only a loop of bowel through or a hole through which the abdominal contents seem to "slide" in and out of the chest cavity. These two types have a much more optimistic prognosis. Diaphragmatic hernia may be associated with other birth defects. As many as 50 percent will have an associated anomaly of the central nervous system, cardiovascular, skeletal, gastrointestinal or genitourinary system. Diaphragmatic hernia occurs in approximately 1 in 2,400 live births. We do not know the cause of diaphragmatic hernia. We know that it is not related to anything the mother ate or did during pregnancy.
Prenatal diagnosis of Congenital Diaphragmatic Hernia
A diaphragmatic hernia may be diagnosed on a routine ultrasound. The heart may be seen shifted to the opposite side of the hernia (the hernia/hole in the diaphragm is usually found on the left side), and intestinal loops may be seen in the chest. There are other anomalies that can look similar. Your obstetrician will refer you to a specialist that handles high-risk pregnancies. These doctors are called perinatologists. Other diagnostic tests may be performed to confirm the diagnosis.
How does the diagnosis congenital diaphragmatic hernia affect the pregnancy?
The diagnosis of diaphragmatic hernia is confirmed by ultrasound. Your obstetrician will refer you to a doctor that cares for high-risk pregnancies. These doctors are called perinatologists. A targeted ultrasound will be needed to evaluate the fetus for other associated anomalies. Amniocentesis with chromosomal analysis will also be offered. Congenital diaphragmatic hernia has a high incidence of associated chromosomal anomalies.
A fetal echocardiogram may also be needed. CDH has a 16 percent incidence of an associated congenital heart defect. Because of the position of the heart with CDH (often times shifted to the right) this evaluation may be difficult to perform. Therefore, the procedure may need to be repeated more than one time.
Close observation of the fetus as the pregnancy progresses may include an ultrasound every two to four weeks to evaluate fetal growth and amniotic fluid volume. At approximately 26 weeks you will be instructed about daily fetal movement counting.
Non-stress tests may begin at approximately 32 weeks' gestation and be done twice weekly. A biophysical profile (BPP) may be done weekly. BPP is an ultrasound study that monitors amniotic fluid volume, the baby's breathing movements and movements of the extremities along with the non-stress test result. Some women will suffer from polyhydramnios with their pregnancy. Polyhydramnios is an increased amount of amniotic fluid. This condition puts a woman at risk for preterm labor and delivery and the baby at risk for health issues related to prematurity. The lungs are one of the last organs to mature, so a baby born prematurely will have lungs that are not fully matured. Immature lungs will further compromise hypoplastic lungs in their ability to effectively exchange gases.
Cesarean section delivery is not necessary for a baby with CDH. A Caesarean delivery would be performed for standard OB indications. It is recommended that these babies be born at a hospital with a Level III neonatal intensive care unit, pediatric cardiologists and pediatric general surgeons who are familiar with the care of a baby with diaphragmatic hernia. Knowing that your baby has CDH allows you the opportunity to plan for the delivery at a hospital that can provide the best care in a timely manner. This may mean you will be delivering some distance from home. If you live locally, we will await spontaneous labor. If you do not live locally a scheduled induction at close to term may be the plan of care.
How does congenital diaphragmatic hernia affect my baby?
At birth the diaphragmatic hernia can have serious affects on your baby's ability to breath. CDH may also affect the blood circulation due to pressure and shifting of the position of the heart. If the diaphragmatic hernia is large, or there is a significant amount of intestines with other abdominal organs within the chest cavity, the lung on the side of the defect, as well as the opposite side may have been affected. If the diaphragmatic hernia is smaller in size, with a lesser amount of intestines within the chest cavity, the lungs may not be as significantly affected. However, at this time there is little to help us predict using prenatal ultrasounds on how sick your baby will be after birth.
Most babies with a diaphragmatic hernia will need immediate interventions after delivery. It is best if they are born at a hospital that can care for baby and mother alike. This keeps the two of you together and avoids the trauma of having to transport the baby after birth.
How is congenital diaphragmatic hernia treated?
At birth, most babies with CDH will need immediate assistance to help them breath. A tube will be passed into the baby's trachea to assist with breathing. This tube passes through the vocal cords so while it is in place the baby will not be able to make sounds. Another tube will be passed through the baby's mouth and into the stomach. This is to keep the stomach decompressed or small in size so it does not press more on the lungs. The baby will quickly be assessed in the delivery room. If at all possible the parents will be allowed to see and hold the baby. As soon as deemed necessary, the baby will be transferred to the Neonatal Intensive Care Unit (NICU) for further stabilizing procedures.
Typically the umbilical cord has two arteries and a vein. A special tube called an umbilical venous catheter (UVC) will be placed in the vein in the umbilical cord so we can give nourishment (vitamins, minerals, calories, fat) and medication for a prolonged period of time. An arterial line called an umbilical artery catheter (UAC) will be placed in one of the arteries of the umbilical cord. IV fluid will be given, blood can be removed for testing and the blood pressure can be monitored through this line.
Some medications before surgery could include:
- Narcotics to keep your baby free from pain.
- Paralytics to keep your baby from moving about.
- Blood pressure medication to maintain an adequate blood pressure.
Surgery to close the hole and move the abdominal contents back into the abdominal cavity is essentially an elective procedure after stabilization and evaluations are done. Surgical repair usually is done after the first week of life. There are two potential problems we need to deal with regarding the lungs. First, the lungs are evaluated for size and ability to oxygenate the body. Lungs that are smaller than normal are hypoplastic. This condition is called pulmonary hypoplasia. This means the lungs are underdeveloped and may not have enough lung volume to sustain life. Another concern is pulmonary hypertension. The degree to which the baby can take in oxygen and remove carbon dioxide through their lungs is monitored (for blood levels) to evaluate these parameters.
Pulmonary hypertension is an increased pressure in the arteries supplying blood to the lungs. This increased pressure shunts blood away from the lungs and decreases the supply of oxygen to the body. This shunting of blood away from the lungs is normal blood flow while the baby is inside the uterus because the baby is not breathing on his/her own. However, once a baby is born these arteries in the lungs need to relax so that blood can flow through the lungs and exchange gases. These gases are exchanged when the blood rids itself of carbon dioxide and pick up oxygen to supply the body. Pulmonary hypertension is a life-threatening complication. If the oxygen levels are low we can attempt some more aggressive treatment options, including nitric oxide therapy and a heart bypass machine.
During nitric oxide therapy, the oxygen content supplied to the baby is decreased and replaced with nitric oxide (NO). NO dilates the pulmonary blood vessels and lowers pulmonary blood pressure. By supplying NO directly into the lungs the pulmonary vasculature (blood vessels in the lungs) relaxes but the systemic blood vessels (blood vessel in the body) do not. This lowers the pressure in the lungs but not the blood pressure in the general body. Blood is able to circulate through the lungs and pick up oxygen and rid itself of carbon dioxide. Unfortunately NO treatment works more effectively in babies with pulmonary hypertension from other causes and does not work as well with CDH.
ECMO, or extra corporeal membrane oxygenation, is a type of heart-lung bypass. ECMO is used when other treatment options fail. While on ECMO the heart and lungs are rested as the machine is now doing their work. This rest will sometimes allow time for resolution of pulmonary hypertension. A baby can stay on ECMO for only a brief period of time, usually 3 to 21 days. Vessels in the neck are used to take the unoxygenated blood out of the body (by a large vein). This blood is put through the ECMO machine and returned to the body via another vessel (an artery) in the baby's neck. A surgical procedure to place cannulas (large intravenous type tubing) into the vessels is performed at the bedside. The blood is heparinized, (heparin, a blood thinner, is put into the blood) to keep it from clotting. Babies on ECMO are cared for in the Pediatric Intensive Care Unit (PICU). ECMO treatment does have risks. The major risk is bleeding. Because of the need to use heparin to thin the blood, there is a risk for bleeding in various parts of the body. The most serious is when bleeding occurs in the brain. Other potential complications can include infection and mechanical failure. An ECMO specialist will be at the bedside at all times to ensure that the system is functioning properly. If a baby is so sick that they require ECMO, the long-term outlook may include neurologic deficits due to a period of time when he/she was not getting enough oxygen to the brain. These deficits can range from mild mental handicaps and/or chronic lung disease (similar to asthma) to more severe problems such as cerebral palsy and vision and hearing deficits. If a decision about whether to use ECMO is needed, the doctors will discuss with you the pros and cons of the treatment.
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| Infant after repair of congenital diaphragmatic hernia. |
What about after surgery?
After surgery your baby will need continued assistance to breath effectively. He/she will need frequent lab work to monitor oxygenation, electrolytes, blood count as well as other things. After surgery your baby may need a variety of medications including: antibiotics to fight infection; pain medication to control post operative pain; blood pressure medication to stabilize and maintain an adequate blood pressure; sedation to keep baby quiet so they do not become agitated; and paralytics to keep the baby from moving. Your baby may look puffy or swollen after surgery. Your baby will not be able to eat until his/her condition has stabilized but will continue to get nourishment through the intravenous (IV) fluids. Because these infants cannot eat for a prolonged period of time, special nourishment is given through the central line or UVC. Total parenteral nutrition (TPN) is an IV solution that contains protein, fats, sugar, vitamins and minerals. This will supply your baby with all his/her nutritional requirements until he/she is able to take food by mouth. We wait for signs from the baby that the bowels are beginning to work. These signs include bowel sounds, spontaneous passing of stool, and a decrease in the amount of drainage coming from the tube in the baby's stomach. Feedings are typically started through the tube that is in the baby's stomach. The amount they start with is very small and gradually increased as we see that the baby is tolerating the food.
Will I be able to help care for my baby?
Yes! Please ask your baby's nurse about ways to interact with and care for your baby. If you had planned on breast-feeding your baby, you can begin to pump your breasts while you are still in the hospital. A lactation consultant can assist in answering your questions. Your milk will be frozen and stored in the NICU until your baby is ready for it. The NICU has breast pumps and private rooms available to you when you are visiting. You can bring in pictures, small toys, booties, and blankets for your baby while he/she is in the NICU.
When can my baby go home?
Your baby will go home when he/she can eat enough to gain weight and lung function is adequate to oxygenate his/her body. The amount of time a baby with a diaphragmatic hernia is in the NICU varies greatly depending on their course of care. An average length of stay is 6 to 12 weeks. Your baby may go home on anti-reflux medication.
What is my baby's long-term prognosis?
Long-term issues include chronic lung disease and gastroesophageal reflux. These babies are assessed for developmental delays due to prolonged hospitalization and ventilation requirements.
For those who do not need ECMO, the survival rate is approximately 90 percent. If the baby would require ECMO, the survival rate does decrease to approximately 50 percent.