A baby's intestine usually develops in the umbilical cord and then moves inside the abdomen. An abdominal wall defect occurs when the intestine fails to move into the abdomen and the baby's intestine develops outside the abdomen. Two common types of abdominal wall defects are gastroschisis and omphalocele
Gastroschisis is an opening or fissure in the anterior abdominal wall lateral to the umbilicus through which the small intestine, part of the large intestine, and occasionally the liver and spleen, may herniate. The opening is separated from the umbilicus by a small bridge of skin, and the herniating organs are not covered by a protective membrane. Gastroschisis usually occurs on the right side of the umbilicus, although it may occur on the left.
Omphalocele is a defect in the anterior abdominal wall in which the umbilical ring is widened, allowing herniation of abdominal organs, including the small intestine, part of the large intestine, and occasionally the liver and spleen, into the umbilical cord. The herniating organs are covered by a nearly transparent membranous sac. The umbilical cord inserts into the sac. The sac is rarely ruptured.
The distinction between gastroschisis and omphalocele is important because they have different causes. Different treatments are also required. In gastroschisis, the umbilicus and cord are normal and separated from the abdominal wall defect by a small bridge of skin. The herniating organs are not covered by a protective membrane. However, they may appear matted and covered by a thick fibrous material as a result of prolonged exposure to amniotic fluid in utero. In omphalocele, abdominal organs herniate through the umbilicus into the umbilical cord. There is no bridge of skin between the abdominal wall defect and the umbilicus and cord. The protective membrane that covers the herniating organs may rupture before, during, or after delivery.
Smoking, malnutrition, and use of certain medications during pregnancy can put babies at higher risk of having gastroschisis, but we do not know what causes the condition. An omphalocele occurs more often in babies of older mothers. Frequently a child who is born with an omphalocele will also have chromosomal anomalies.
A diaphragmatic hernia is a third type of abdominal wall defect. A diaphragmatic hernia is an opening that forms in the diaphragm. This opening allows some of the baby's organs that should be in the abdomen to move into the baby's chest cavity. The child's doctors will discuss the type of corrective surgery that is needed to repair the hernia.
*Birth defects image credit: Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities