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Congenital Diaphragmatic Hernia
Thursday, 19 August 2004
Sunday, 28 November 2004

What

Congenital Diaphragmatic Hernia (CDH) is a life-threatening illness that occurs when a hole in the diaphragm, the flat muscle that separates the chest from the abdomen, fails to close before the baby is born. This birth defect develops in the first trimester, usually on the left side of the diaphragm. When a baby has a hole in its diaphragm, the organs of the abdomen, including the stomach, intestine, and liver, can move into the chest. As a result, the lungs cannot grow and develop normally, causing a condition called pulmonary hypoplasia.

Who

CDH occurs in one in every 2,500 births. The risk of recurrence for future siblings is approximately 2%. Boys are affected 1.5 times more frequently than girls. It is not contagious or preventable. Familial CDH, usually by an autosomal recessive inheritance, occurs rarely.

Signs and Symptoms

While in the uterus, the fetus does not need its lungs to breathe because oxygen is delivered through the mother's placenta. However, after birth the lungs play a crucial rule in supplying oxygen. If the lungs have not developed normally, the baby will not get enough oxygen to survive. Depending on the size of the hole in the diaphragm (hernia), infants with CDH have a variable degree of both lungs being underdeveloped. One lung is compressed by abdominal contents and the opposite lung can be compressed by the displaced heart. In pulmonary hypoplasia the number of air sacs (gas exchange units) in the lungs is reduced. In addition, there may be deficiency of surfactant, an important lubricating fluid necessary for air sac expansion. Also, the lung arteries may be abnormally constricted. As a result, pulmonary hypertension develops and oxygenation is difficult. Ninety percent of babies with CDH have trouble breathing and turn blue at birth. On physical examination, the baby’s abdomen may be thin or caved in because of the displaced abdominal organs. Thirty to forty percent of infants have additional malformations involving the heart, intestines, or genitourinary system.

Possible Causes

The cause of CDH is unknown. It is likely multifactorial, including both genetic and environmental effects which are yet to be identified. It cannot be blamed on anything the parents did or did not do. Chromosomal abnormalities, such as extra copies of chromosomes 12, 13, 18, or 21 have been reported in 4% of infants with CDH. However, no single gene mutation has been identified.

Diagnosis

The diagnosis of CDH can be made on prenatal ultrasound as early as the second trimester. Prenatal diagnosis can be confirmed by an MRI scan. MRI scan will show the severity of the defect, namely the size of the lungs and whether the liver has herniated. After birth, a chest X-ray will reveal intestinal and/or liver herniation in the chest cavity. Echocardiogram of the heart is very important to determine the presence of heart defects, found in up to 25% of patients with CDH. Chromosomal studies may be obtained, especially if other abnormalities are found. In this case, consultation with a geneticist is useful. Renal ultrasound is also necessary to rule out kidney abnormalities. A minority of patients with CDH, whose diaphragm defect is very small and the lungs are well developed, will not be diagnosed until adulthood. Common complaints include mild breathing problems, vomiting or stomach reflux.

Treatment

If possible, the baby should be born at a medical center equipped with a neonatal intensive care unit with the ability to do ECMO (extracorporal membrane oxygenation). At birth, most infants are critically ill and require a machine to help them breathe. A tube is placed in the wind pipe (trachea) and attached to a machine which provides breaths to the baby. High frequency ventilation, a special high-speed breathing machine, may be required. An arterial catheter is placed to closely monitor oxygen levels in the blood and blood pressure. Venous catherization is also required to administer fluids and medications. These catheters are often placed through the umbilical cord. Care must be taken to minimize stimulation of the baby as it can worsen the pulmonary hypertension. This includes reducing handling and invasive procedures. Often sedatives are required to keep the baby calm. It is best to delay surgery until the baby is stable and pulmonary hypertension is resolved. In the meanwhile the baby is fed intravenously, and the lungs are allowed to develop. Surgery is usually performed after a week of life. The abdominal organs are placed back into the abdominal cavity and the diaphragm is repaired. If all of the above measures are not sufficient, ECMO can be used. In this procedure, the baby’s blood circulates through a heart-lung machine, similar to cardiac bypass. The machine oxygenates the blood and pumps it back to the baby’s body. ECMO is a temporary solution that gives the lungs time to develop prior to surgery. Because blood thinning is required during ECMO to prevent clots, ultrasound of the head is performed regularly to check for bleeding in the brain. Once the baby demonstrates the ability to tolerate weaning from ECMO, surgery can be performed. Surgery to repair the hernia before the baby is born is reserved for very severely affected fetuses, namely those with an expected survival rate less than 50%. In-utero surgery is only performed in a few medical centers around the world. In this surgery, the trachea is blocked forcing the lung fluid back into the lungs instead of allowing it to escape through the mouth into the amniotic fluid. As the fluid builds up in the lung, it pushes the abdominal contents out of the chest and back into the abdomen. Complications of tracheal ligation include premature delivery.

Prognosis

Approximately 50% of infants with CDH will not survive. Infants with large herniation, liver herniation or multiple anomalies have higher mortality rates. Those who show symptoms in adulthood have a very good prognosis. The most common complications in CDH survivors are chronic lung disease (asthma-like, 75%), stomach reflux (75%), and neurodevelopmental delays. Ten percent of CDH survivors may require oxygen therapy at home. Neurological abnormalities are common in CDH survivors, especially ECMO survivors. They include developmental delay, hearing/vision loss and/or seizures. The majority of neurological abnormalities are mild to moderate. Regular follow-up with a neonatologist or pulmonologist, neurologist, and developmental specialist is needed. Hearing is checked prior to discharge and periodically thereafter. Medications to help with breathing and to decrease stomach acid reflux may be needed. Growth and feeding problems occur in most children and many require stomach surgery for persistent stomach acid reflux. Lastly, physical, occupational, and speech therapy are helpful to improve muscle strength and coordination.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

CHERUBS
This is a well-constructed site for The Association for congenital Diaphragmatic Hernia Research, Advocacy, and Support.

WebRing
This website ring for people with congenital Diaphragmatic Hernia contains multiple links to families personal stories.

Children s Hospital Boston
An excellent overview of CDH with clear pictures and descriptions.

Google Search for Congenital Diaphragmatic Hernia

References and Sources

Author unknown (2004) Congenital diaphragmatic hernia, In: Behrman RE, Kliegman RM, Jenson HB (eds) Nelson Textbook of Pediatrics, 17th ed Elsevier , p.1353-1357. www.emedicine.com/ped/topic2603.htm www.ucsfhealth.org/childrens/medical_services/surgical/fetal/conditions/hernia/treatments.html