True congenital umbilical hernia, described by other authors under the names exomphalos, omphalocele or hernia funiculi umbilicalis, is a relatively rare condition. It has been described as occurring about once in every 5,000 to 6,000 births, and it is apparently more common in the male than in the female.
As a type, it is differentiated from the true postnatal umbilical hernia and from the rare and more extensive defects of the abdominal wall that result in ectopy of the abdominal viscera. The latter class, which has also been described under the classification of fissurae abdominales, is not a true hernia, as there is no true umbilical ring but rather an extensive hiatus in the abdominal wall resulting in varying grades of malformation and eventration. The postnatal umbilical hernia so commonly seen differs from true congenital hernia in that it is more eccentrically situated about the umbilicus and in that it
MILCH H. ADHERENT CONGENITAL UMBILICAL HERNIA. Am J Dis Child. 1931;42(3):608-610. doi:10.1001/archpedi.1931.01940150107008