Definition of Omphalocele

Omphalocele: A birth defect in which part of the intestine, covered only by a thin transparent membrane, protrudes outside the abdomen at the umbilicus. The underlying error is a failure during embryonic development for a section of the intestines (the midgut) to return from outside the abdomen and reenter the abdomen, as it should. The opening in the abdominal wall cannot close because, to do so, would pinch off part of the intestines. An omphalolocele must be repaired by surgery.

With an omphalocele, the part of the intestine that sticks out is covered by two thin transparent membranes called the amnion (the amniotic membrane) and peritoneum (the abdominal membrane). The liver and spleen may also be within the omphalocele.

An omphalocele is caused by an error in the normal embryonic development of the intestinal tract. During embryogenesis (the time during which the embryo forms), there are initially three distinct portions of the intestinal tract (the foregut, midgut and hindgut) that extend the length of the embryo. Much of the midgut is then herniated (protruded) outside the abdomen at the umbilicus (belly button). The midgut later reenters the abdomen (belly) and the opening in the abdominal wall closes. The error responsible for an omphalocele is a failure for the midgut to return and reenter the abdomen. The opening in the abdominal wall cannot close because to do so would pinch off part of the intestines.

About 1 in 5,000 babies is born with an omphalocele. The omphalocele can be an isolated birth defect (all by itself). Or it may occur in children who have additional malformations as for example a congenital heart defect. Omphalocele is a characteristic malformation in certain chromosome abnormalities as the trisomy 13 (Patau) syndrome and the trisomy 18 (Edwards) syndrome. It also is seen in some genetic disorders such the Beckwith-Wiedemann syndrome.

"Omphalo-" indicates a relationship to the umbilicus (the navel) and the suffix "-cele" refers to a hernia or rupture, so omphalocele literally = a hernia or rupture at the umbilicus.