An umbilical hernia is an abnormal bulge that can be seen or felt at the umbilicus (belly button). This hernia develops when a portion of the lining of the abdomen, part of the intestine, and / or fluid from the abdomen, comes through the muscle of the abdominal wall.
Umbilical hernias are common, occurring in 10 percent to 20 percent of all children. They are, however, more common in African-Americans.
Low birth weight and premature infants are also more likely to have an umbilical hernia. Boys and girls are equally affected.