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.
Other "O" facts:
- Many babies born with an omphalocele also have other abnormalities. The chance for reoccurrence depends upon the underlying disorder. Thirty percent have a chromosomal (genetic) abnormality. More than half of babies with omphalocele have abnormalities of other organs or body parts, most commonly the spine, digestive system, heart, urinary system, and limbs.
- 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.
- (Thanks to www.chp.edu for the info and Medline Plus for the picture!)