DIGESTIVE/LIVER DISORDERS :: Prenatal Digestive Tract Development
What is an omphalocele?
An omphalocele is a birth defect, which is an abnormality that occurs before birth as a fetus is forming in its mother's uterus. Some of the abdominal organs protrude through an opening in the abdominal muscles in the area of the umbilical cord. A translucent membrane covers the protruding organs.
The omphalocele may be small, with only a portion of the intestine protruding outside the abdominal cavity, or large, with most of the abdominal organs (including intestine, liver, and spleen) present outside the abdominal cavity. Further, the abdominal cavity itself may be small due to underdevelopment during pregnancy.
What causes an omphalocele?
As a fetus is growing in the mother's uterus before birth, different organ systems are developing and maturing. Between the 6th and the 10th weeks of pregnancy, the intestines actually project into the umbilical cord as they are growing. By the 11th week of development, the intestines should return to the abdomen. When the fetus is growing and developing during pregnancy, there is a small opening in the abdominal muscles that the umbilical cord can pass through, connecting the mother to the fetus. As the fetus matures, the abdominal muscles should meet in the middle and grow together, closing off this opening. An omphalocele occurs when the abdominal organs do not return to the abdominal cavity as they should.
It is not known what causes omphalocele. Steps that normally happen in the development of the abdominal organs and muscles simply did not happen properly. It is not known to be caused by anything the mother did during pregnancy.
Who is at risk for developing an omphalocele?
When an omphalocele is isolated (no other birth defects are present), the risk for it to happen in a future pregnancy is one percent or one in 100. There are some families that have been reported to have an omphalocele inherited as an autosomal dominant or X-linked recessive trait. In these cases, the chance for reoccurrence would be higher.
Many babies born with an omphalocele also have other abnormalities. The chance for reoccurrence depends upon the underlying disorder:
How often does an omphalocele occur?
A "small" type omphalocele (involving protrusion of a small portion of the intestine only) occurs in one out of every 5,000 live births.
A "large" type omphalocele (involving protrusion of the intestines, liver, and other organs) occurs in one out of every 10,000 live births.
More boys than girls are affected with omphalocele.
Why is an omphalocele a concern?
Since some or all of the abdominal organs are outside the body, infection is a concern, especially if the protective membrane around the organs breaks. Also, an organ may lose its blood supply if it becomes pinched or twisted. A loss of blood flow can damage the affected organ.
How is an omphalocele diagnosed?
Omphalocele can often be detected on fetal ultrasound in the second and third trimesters of pregnancy. A fetal echocardiogram (ultrasound of the heart) may also be done to check for heart abnormalities before the baby is born.
After birth, the omphalocele can be noted by the physician during the physical examination. X-rays (diagnostic tests which use invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film) may also be done after birth to evaluate abnormalities of other organs or body parts.
Treatment for an omphalocele:
Specific treatment for an omphalocele will be determined by your baby's physician based on the following:
For a "small" omphalocele (only a portion of the intestine protruding outside the abdominal cavity), shortly after birth, an operation is done to return the organs to the abdomen and close the opening in the abdominal wall.
For a "large" omphalocele (most of the abdominal organs, including intestine, liver, and spleen are present outside the abdominal cavity), the repair is done in "stages" and may include the following:
Because the abdominal cavity may be small and underdeveloped, and the organs may be swollen, a baby with an omphalocele may have breathing difficulties as the organs are returned to the abdomen. Your baby may need help from a breathing machine called a mechanical ventilator while the swelling is decreasing and the size of the abdominal cavity is increasing.
What is the long-term outlook for a baby born with an omphalocele?
Problems in the future often depend on:
Babies who have damage to the intestines or other abdominal organs may have long-term problems with digestion, elimination, and infection.
Consult your baby's physician regarding the prognosis for your baby.
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