Embryology of the umbilicus and associated newborn defects

Congenital abdominal wall abnormalities are a common group of disorders that result from abnormal development of the abdominal wall. Ventral body wall defects range from the relatively minor umbilical and epigastric hernias to major defects such as gastroschisis and omphalocele. This chapter will focus on the embryology of the umbilicus and associated common umbilical defects and postnatal problems. The physiologic importance of the umbilicus and umbilical cord is far greater during fetal development than it is after birth. During abdominal wall development, the developing umbilicus serves a role in intestinal and urinary development and provides a life-sustaining opening that allows blood to flow between the placenta and fetus via the umbilical cord. After birth this conduit is no longer needed, and once the umbilical cord falls off, there should be no remaining connections. Nevertheless, umbilical disorders are frequently encountered.