I Congenital diaphragmatic hernia (CDH)
Congenital diaphragmatic hernia (CDH) is a rare birth defect involving a 'rupture' (hernia) in the diaphragm. The diaphragm is a flat muscle that separates the abdominal cavity from the chest. It is formed during the tenth week of pregnancy. The diaphragm also helps with breathing. The hernia may cause part of the abdominal contents to enter the thoracic cavity. This leads to underdevelopment of the lungs (lung hypoplasia) and displacement of the heart to the other side of the body.
The defect usually occurs on the left side (80%), and sometimes on the right. On the right side it does not always cause problems because the liver on the right side of the abdomen can close the defect. If part of the liver ends up in the thoracic cavity, it does cause symptoms. With a left-sided defect, the stomach, intestines or spleen can end up in the thoracic cavity. The defect in the diaphragm causes the contents of the abdomen to enter the thoracic cavity and to displace the lung. This leads to underdevelopment of the lung, with less branching of the respiratory tract and an abnormal formation of blood vessels. This can lead to high pressure in the blood vessels of the lungs (pulmonary hypertension). The degree of underdevelopment of the lungs and the severity of the high blood pressure in the lungs determine the course of this disease and its long-term consequences.
The left-hand drawing shows the healthy situation in which the diaphragm is closed. In the middle drawing the diaphragm on the left has a rupture. The right-hand drawing shows that the intestines enter the thoracic cavity through the rupture, leaving the lungs with less space to develop. The life expectancy of children with congenital diaphragmatic depends largely on the location of the defect and the degree of development of the lungs.
II Abdominal wall defects
An omphalocele is a defect of the muscles of the abdominal wall that develops in the fatal stage. The intestines, liver and occasionally other organs are then located outside of the abdomen in a translucent membrane sac. The defect can be small, with only a small loop of intestines present outside the abdomen, or large, with most of the abdominal organs protruding from the abdomen (giant omphalocele). In severe cases surgical treatment is complicated by the abnormally small volume of the infant’s abdomen – as there was no need for expansion to accommodate the developing organs. Giant omphalocele is often associated with lung hypoplasia (sometimes severe) for which respiratory support is needed.
Approximately 25–40% of infants with an omphalocele have other birth defects. These may include genetic problems (chromosomal abnormalities), congenital diaphragmatic hernia, and heart defects. A ’small’ type omphalocele (involving protrusion of a small portion of the intestine only) occurs in one of every 5,000 live births. A giant omphalocele (involving protrusion of the intestines, liver, and other organs) occurs in one of every 10,000 live births.
Gastroschisis is a rare condition that develops between weeks 8-11 of pregnancy. It consists of a defect in the abdominal wall to the right of the navel. The size of the defect may vary. Due to this defect, abdominal organs bulge outwards and lie freely in the uterus or on the abdomen after birth. The large and small bowel, spleen, stomach and sometimes the liver are involved. Because the intestines are outside the abdomen, they can become irritated and thickened.