As a fetus is developing, it’s normal for digestive organs like the intestines to protrude outside of the abdomen and into the umbilical cord. Then, as the fetus develops further, those organs move inside the abdomen and are enclosed by the abdominal wall. When an abdominal wall defect occurs, the abdominal wall does not close as it should and some of the organs remain outside the abdomen.
There are several different types of abdominal wall defects, but the two primary types are omphalocele and gastroschisis. These conditions have many similarities — including how they are treated. Because these defects impair a newborn’s ability to digest food, they both require surgery after birth to put the affected organs in their proper locations.
While omphalocele occurs in about one out of every 5,000 infants, gastroschisis is more common and occurs in one of approximately 2,000 live births. In recent years, cases of gastroschisis have been on the rise, although no single cause has been determined.
This defect occurs early in pregnancy and results in a baby’s abdominal organs remaining outside the abdomen. They protrude through the baby’s belly button and are only protected by a thin sac. Oftentimes this only affects the intestines, but a “giant” omphalocele may include the liver as well.
One of the greatest dangers is that the sac can rupture and lead to organ damage or infection. A baby with omphalocele often has smaller lungs because the abdominal organs provide a framework for growth of the chest wall. In addition to respiratory problems, individuals with omphalocele frequently have other birth defects, such as a congenital heart defect. This type of abdominal defect can also be accompanied by genetic syndromes, which is why your doctor will likely recommend genetic testing after an omphalocele diagnosis.
Omphalocele carries an increased risk of stillbirth; however, the survival rate for babies with an omphalocele without other abnormalities is close to 90%.
Gastroschisis is a type of abdominal wall defect that is also characterized by a hole in the baby’s belly wall. Instead of protruding through the belly button, the hole is next to the belly button. This allows the intestines to push through to the outside, and unlike with an omphalocele, there is no protective sac covering the organs. This can result in the intestines becoming irritated, swollen, or damaged.
Most babies diagnosed with gastroschisis go on to lead healthy lives after surgical interventions. It is usually not associated with other malformations, but infants with gastroschisis can have problems with nursing and eating. The amount of care each baby needs will depend upon how severe the defect is and what associated symptoms are present.
What Causes Fetal Abdominal Wall Defects?
No specific causes have been identified for the development of abdominal wall defects. Risk factors include certain antidepressant medications, smoking, and maternal obesity. However, a specific link has not yet been identified.
Diagnosis of Fetal Abdominal Wall Defects
Both omphalocele and gastroschisis are typically diagnosed by ultrasound during the second trimester of pregnancy. The defect can also cause abnormal results to occur on a prenatal blood screening test. If the abnormality is not detected during pregnancy, it will become apparent when the baby is born.
If a prenatal diagnosis is made, additional tests such as an amniocentesis may be recommended to see if chromosomal abnormalities or genetic syndromes are present. Regularly scheduled ultrasounds for the remainder of your pregnancy will be recommended to follow the baby’s development and detect any other issues that might arise before birth.
How Are Fetal Abdominal Wall Defects Treated?
Fetal abdominal wall defects are treated with surgery after the baby is born. This surgical repair will place the organs back inside your baby’s belly and close the opening in the abdominal wall. Many factors affect the extent of the surgical procedure, including whether or not there is blockage in the intestines, how much of the organ is located outside of your baby’s belly, and whether or not there are other problems, such as respiratory issues.
In some cases, a phased surgical approach may be required to gradually return the abdominal organs to the belly. This is done to give the abdominal wall sufficient time to stretch so it is large enough to accommodate the organs, or to provide time for underdeveloped lungs to grow and expand.
In more severe cases of omphalocele, physicians will allow the body to grow skin over the protruding membrane sac and perform surgical repair of the defect when your child is 1 to 2 years old.
What Other Fetal Abdominal Wall Defects Are There?
Other abdominal wall defects treated by Fetal Care Center Dallas include:
- Ectopia cordis, a rare defect in which the heart develops outside the chest wall
- Body-stalk anomaly, in which the baby’s abdominal organs develop outside of the abdominal cavity and remain attached to the placenta
- Pentalogy of Cantrell, which affects the sternum, diaphragm, pericardium, abdominal wall, and heart
- Cloacal exstrophy (OEIS Syndrome), in which the bladder and part of the intestines are outside of the body
- Bladder exstrophy, a milder form of cloacal exstrophy in which the bladder is underdeveloped and exposed on the outside of the abdominal wall