Exomphalos

An omphalocele is a protrusion at birth of part of the intestine through a defect in the abdominal wall at the umbilicus, occurring once in every 5,000 births. It is due to failure of the intestine to return to the abdomen during early foetal life. Sometimes a large sac ruptures during birth causing peritonitis and often death. In other cases, the sac remains unruptured. It is semi-translucent and very thin. It comprises three layers - amniotic membrane on the outside, Wharton's jelly in the middle and inner peritoneum.

There are two varieties:

• exomphalos minor - the sac is relatively small with the umbilicus attached to its summit
• exomphalos major - the sac is larger and the umbilicus is attached to its inferior aspect. It contains small and large bowel, and almost certainly, a portion of the liver.

Intra-uterine epithelialisation of a small exomphalos may present a fully formed umbilical hernia at birth.

Reference

1. Salihu HM, Boos R, Schmidt W. Omphalocele and gastroschisis. J Obstet Gynaecol. 2002 Sep;22(5):489-92.