Congenital Diaphramatic Hernia FAQ

What is congenital diaphragmatic hernia (CDH)?

Congenital diaphragmatic hernia (CDH) occurs when the diaphragm muscle fails to close completely while the fetus is developing inside the mother's uterus. The diaphragm is the muscle used for breathing and separates the chest cavity from the abdominal cavity. In babies with CDH, the opening in the diaphragm allows some of the abdominal organs (intestines, stomach, liver) to move into the chest cavity. When the abdominal organs are in the chest cavity, the lungs are not able to fully develop, which results in pulmonary hypoplasia (decreased size and weight of the lungs). In addition, the abdominal organs can push on the heart and prevent it from growing normally. As a result, the tiny air sacs and blood vessels in the lungs are underdeveloped and do not function properly. Because the diaphragm muscle forms between the eighth and tenth week of pregnancy, CDH typically occurs very early in the pregnancy.

There are two types of diaphragmatic hernia:

• Bochdalek hernia. This type involves an opening on the back side of the diaphragm. The stomach, intestines and liver or spleen usually move up into the chest cavity.

• Morgagni hernia. This type is rare and involves an opening in the front of the diaphragm, just behind the breast bone. The liver or intestines may move up into the chest cavity.

Why does congential diaphragmatic hernia occur?

Although we do not completely understand why CDH occurs, we do know there is nothing specific that a mother or father did or did not do to cause their developing baby to have CDH. CDH is considered to be a "multifactoral" condition involving a combination of many genetic and environmental factors. It is believed that multiple genes from both parents coupled with a number of environmental factors contribute to the malformation of the diaphragm.

How common is congenital diaphragmatic hernia?

CDH occurs in about one in every 3,000 to 4,000 live births.

What tests are used to diagnose congenital diaphragmatic hernia?

CDH is often discovered during a routine prenatal ultrasound around the 20th week of the pregnancy. The ultrasound may show abdominal organs (intestines, stomach, liver) in the chest cavity where the lungs should be. In some cases, CDH is not apparent on the prenatal ultrasound, and the diagnosis is made after the birth of the baby. Typically, a chest x-ray is performed to detect abnormalities in the lungs. Other tests that may be performed include:

• abdominal x-ray

• arterial blood gas – test used to measure the amount of oxygen in the blood

• echocardiogram – a type of ultrasound that takes images of the heart using sound waves. This test is performed to check for heart defects and determine how well the baby’s heart is working.

• karyotype – a blood test used to detect abnormalities of the chromosomes to determine there is a genetic syndrome

What is pulmonary hypertension?

Infants with CDH also commonly have a very serious and potentially life-threatening problem called pulmonary hypertension. Pulmonary hypertension happens because the blood vessels in the lungs are not formed properly. During pregnancy, blood flow to the baby’s lungs is restricted by tiny muscles that squeeze the vessels. After birth, these lung blood vessels gradually relax so that more blood can enter the lungs. In babies with CDH, however, the blood vessels often fail to relax normally. In addition, babies with CDH have an inadequate number of blood vessels to carry blood into the lungs. Therefore, the lungs receive inadequate blood flow which restricts the amount of oxygen delivered to the rest of the body. Further, because the heart has to work extra hard to pump blood through the tiny blood vessels in the lungs, it can eventually begin to fatigue.

Are other birth defects associated with congenital diaphragmatic hernia?

There is a 33 percent (approximately one in three) chance that a baby with CDH will have another birth defect. Heart defects are the most commonly associated abnormality, and trisomy 21 (Down syndrome) occurs in five to sixteen percent of infants with CDH.

What is the expected outcome for a baby with congenital diaphragmatic hernia?

There is a wide range of outcomes for infants born with CDH, depending on how severely the lungs are affected and whether or not the baby has other birth defects. At best, the baby does quite well and requires minimal (if any) additional treatment after birth. In the most severe cases, the infant will not survive regardless of how much life support is used. Most babies with CDH fall somewhere in the middle of this range and require some degree of extra treatment for days to months after birth but are ultimately able to lead normal lives. At Duke, our outcome statistics are consistent with those found in published national and international reports.

What are the long-term effects of congenital diaphragmatic hernia?

Studies have shown that infants and children born with CDH may have medical and/or developmental difficulties during the first few months to first few years of life. During this time, children with CDH are at an increased risk for growth and nutritional disorders, may suffer from reactive airway disease (coughing, wheezing, or shortness of breath) or asthma, and experience developmental delay and behavioral problems. There is a wide variety of long-term outcomes depending on the individual child and his or her unique medical history.

It is important that infants and children with CDH receive regular follow-up care by trained specialists to ensure that they reach their optimum medical and developmental potential. The Special Infant Care Clinic (SICC) at Duke is a multidisciplinary medical and neurodevelopmental follow-up clinic for high risk infants that comprises a staff of neonatologists, general pediatricians, child psychologists, physical therapists, occupational therapists, speech therapists, social workers, a nurse clinician, and a nutritionist. For detailed information about the SICC, please visit the Department of Pediatrics Division of Neonatology web site.