In abdominal wall defects, the muscles surrounding the abdominal cavity are weak or develop holes, allowing the intestines to spill out.
The two main abdominal wall defects are omphalocele and gastroschisis.
Omphalocele
An omphalocele is caused by an opening (defect) in the middle of the abdominal wall at the bellybutton (umbilicus). The skin, muscle, and fibrous tissue are missing. The intestines spill (herniate) out through the opening and are covered by a thin sac. The umbilical cord is in the center of the defect.
An omphalocele commonly occurs along with other birth defects (such as heart defects and kidney defects) and with specific genetic syndromes (such as Down syndrome, trisomy 18, trisomy 13, and Beckwith-Wiedemann syndrome).
Gastroschisis
Gastroschisis also is an abnormal opening of the abdominal wall. In gastroschisis, the opening is near the bellybutton (usually to the right) but not directly over it, like in omphalocele. Like in omphalocele, the opening allows the intestines to spill out but unlike omphalocele, the intestines are not covered by a thin sac.
Before birth, because the intestines are not covered by a sac, they may be damaged by exposure to amniotic fluid, which causes inflammation. The inflammation irritates the intestine, which can result in complications such as problems with movements of the digestive system, scar tissue, and intestinal obstruction.
(See also Overview of Digestive Tract Birth Defects.)
Diagnosis of Abdominal Wall Defects
Blood tests
Usually prenatal ultrasonography
Doctors may suspect gastroschisis if the level of alpha-fetoprotein (a protein produced by the fetus) in the mother's blood is abnormally high during pregnancy.
Both omphalocele and gastroschisis are usually diagnosed before birth with routine prenatal ultrasonography. If not, the defects are very obvious as soon as the infant is delivered.
Treatment of Abdominal Wall Defects
Surgery
Once the infant is delivered, the exposed intestines are covered with a sterile dressing to keep them moist and protected and the infant is given fluids and antibiotics by vein. A long, thin tube is passed through the nose and placed in the stomach or intestine (nasogastric tube) to drain digestive fluid that collects in the stomach.
Surgery is required to replace the intestines in the abdomen and close the opening. If possible, surgery to repair the defect is done soon after birth. However, the skin of the abdominal wall often must be stretched for a few days before surgery so there is enough tissue to cover the opening. If the defect is large, doctors may need to create skin flaps to close it. If a large amount of intestine is sticking out, it is wrapped in a protective covering (called a silo) and gradually moved back into the abdomen over several days or weeks. When all the intestines are back in the abdomen, the opening is surgically closed.
