Congenital diaphragmatic hernia

Other Names: CDH; Congenital diaphragmatic defect; Unilateral agenesis of diaphragm; Agenesis of hemidiaphragm

Congenital diaphragmatic hernia (CDH) is a condition present before birth characterized by abnormal development of the diaphragm.

The diaphragm, which is composed of muscle and other fibrous tissue, separates the organs in the abdomen from those in the chest. Abnormal development of the diaphragm before birth leads to defects ranging from a thinned area in the diaphragm to its complete absence. An absent or partially formed diaphragm results in an abnormal opening (hernia) that allows the stomach and intestines to move into the chest cavity and crowd the heart and lungs. This crowding can lead to underdevelopment of the lungs (pulmonary hypoplasia), potentially resulting in life-threatening breathing difficulties that are apparent from birth.

Classification

Congenital diaphragmatic hernias are often classified by their position.

A Bochdalek hernia is a defect in the side or back of the diaphragm. Between 80 and 90 percent of congenital diaphragmatic hernias are of this type.

A Morgnani hernia is a defect involving the front part of the diaphragm. This type of congenital diaphragmatic hernia, which accounts for approximately 2 percent of cases, is less likely to cause severe symptoms at birth.

Other types of congenital diaphragmatic hernia, such as those affecting the central region of the diaphragm, or those in which the diaphragm muscle is absent with only a thin membrane in its place, are rare.

Epidemiology

Congenital diaphragmatic hernia affects approximately 1 in 2,500 newborns.

Cause

• Congenital diaphragmatic hernia has many different causes. In 10 to 15 percent of affected individuals, the condition appears as a feature of a disorder that affects many body systems, called a syndrome. Donnai-Barrow syndrome, Fryns syndrome, and Pallister-Killian mosaic syndrome are among several syndromes in which congenital diaphragmatic hernia may occur. Some of these syndromes are caused by changes in single genes, and others are caused by chromosomal abnormalities that affect several genes.
• About 25 percent of individuals with congenital diaphragmatic hernia that is not associated with a known syndrome also have abnormalities of one or more major body systems. Affected body systems can include the heart, brain, skeleton, intestines, genitals, kidneys, or eyes. In these individuals, the multiple abnormalities likely result from a common underlying disruption in development that affects more than one area of the body, but the specific mechanism responsible for this disruption is not clear.
• Approximately 50 to 60 percent of congenital diaphragmatic hernia cases are isolated, which means that affected individuals have no other major malformations.
• More than 80 percent of individuals with congenital diaphragmatic hernia have no known genetic syndrome or chromosomal abnormality. In these cases, the cause of the condition is unknown. Researchers are studying changes in several genes involved in the development of the diaphragm as possible causes of congenital diaphragmatic hernia. Some of these genes are transcription factors, which provide instructions for making proteins that help control the activity of particular genes (gene expression). Others provide instructions for making proteins involved in cell structure or the movement (migration) of cells in the embryo. Environmental factors that influence development before birth may also increase the risk of congenital diaphragmatic hernia, but these environmental factors have not been identified.

Inheritance

Isolated congenital diaphragmatic hernia is rarely inherited. In almost all cases, there is only one affected individual in a family.

When congenital diaphragmatic hernia occurs as a feature of a genetic syndrome or chromosomal abnormality, it may cluster in families according to the inheritance pattern for that condition.

Signs and symptoms

In 5 to 10 percent of affected individuals, signs and symptoms of congenital diaphragmatic hernia appear later in life and may include breathing problems or abdominal pain from protrusion of the intestine into the chest cavity. In about 1 percent of cases, congenital diaphragmatic hernia has no symptoms; it may be detected incidentally when medical imaging is done for other reasons.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Congenital diaphragmatic hernia

30%-79% of people have these symptoms

• Abnormality of cardiovascular system morphology
• Aplasia/Hypoplasia of the diaphragm(Absent/small diaprhagm)
• Hypoxemia(Low blood oxygen level)
• Intestinal malrotation
• Prominent sternum
• Pulmonary hypoplasia(Small lung)
• Respiratory distress(Breathing difficulties)

Diagnosis

Fetal ultrasound may show abdominal organs in the chest cavity. The pregnant woman may have a large amount of amniotic fluid.

An exam of the infant shows:

• Irregular chest movements
• Lack of breath sounds on side with the hernia
• Bowel sounds that are heard in the chest
• Abdomen that looks less protuberant than a normal newborn's and feels less full when touched
• A chest x-ray may show abdominal organs in the chest cavity.

Treatment

Treatment options depend on the type and severity of the defect and typically include surgery. Prenatal diagnosis and medical advances have increased the survival rate, but various long-term complications affecting health and development may occur.

Prognosis

The long-term outlook (prognosis) for those with congenital diaphragmatic hernia (CDH) depends on a number of factors and is hard to predict. A large defect is more likely to result in pulmonary hypoplasia (underdevelopment of the lungs) and death than a small defect. Other factors associated with decreased survival include:

• premature birth
• having a chromosome abnormality or single gene disorder
• the presence of other severe birth defects such as a heart defect
• having a right-sided defect or bilateral CDH (on both sides)
• liver herniation
• a lower fetal lung volume

The postnatal survival rate at tertiary centers (providing specialized care) has improved, with reported rates of 70 to 92 percent. However, these data represent the survival rate of cases that were full-term infants born or transferred to tertiary care centers with available skilled personnel and access to advanced technology.

NIH genetic and rare disease info

• NIH info on Congenital diaphragmatic hernia

Congenital diaphragmatic hernia is a rare disease.

Congenital diaphragmatic hernia Resources
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