In some, it may be just a small protrusion; in others it may be a large rounded swelling that bulges out when the baby cries. It may hardly be visible when the child is quiet and or sleeping.Normally, the abdominal muscles converge and fuse at the umbilicus during the formation stage, however, in some cases, there remains a gap where the muscles do not close and through this gap the inner intestines come up and bulge under the skin, giving rise to an umbilical hernia. The bulge and its contents can easily be pushed back and reduced into the abdominal cavity.In contrast to an inguinal hernia, the complication incidence is very low, and in addition, the gap in the muscles usually closes with time and the hernia disappears on its own. The treatment of this condition is essentially conservative: observation allowing the child to grow up and see if it disappears. Operation and closure of the defect is required only if the hernia persists after the age of 3 years or if the child has an episode of complication during the period of observation like irreducibility, intestinal obstruction, abdominal distension with vomiting, or red shiny painful skin over the swelling. Surgery is always done under anesthesia. The defect in the muscles is defined and the edges of the muscles are brought together with sutures to close the defect.
Causes
The causes of umbilical hernia are congenital and acquired malformation, but an apparent third cause is really a cause of a different type, a paraumbilical hernia. Congenital
Congenital umbilical hernia is a congenital malformation of the navel (umbilicus). Among adults, it is three times more common in women than in men; among children, the ratio is roughly equal. It is also found to be more common in children of African descent. Acquired
An acquired umbilical hernia directly results from increased intra-abdominal pressure caused by obesity, heavy lifting, a long history of coughing, or multiple pregnancies. Another type of acquired umbilical hernias are incisional hernias, which are hernia developing in a scar following abdominal surgery, e.g. after insertion of laparoscopy trocars through the umbilicus. Paraumbilical
Importantly, an umbilical hernia must be distinguished from a paraumbilical hernia, which occurs in adults and involves a defect in the midline near to  the umbilicus, and from omphalocele. Diagnosis
Navels with the umbilical tip protruding past the umbilical skin ("outies") are often mistaken for umbilical hernias, which are a completely different shape. Treatment for cosmetic purposes is not necessary, unless there are health concerns such as pain, discomfort or incarceration of the hernia content. Incarceration refers to the inability to reduce the hernia back into the abdominal cavity. Prolonged incarceration can lead to tissue ischemia (strangulation) and shock when untreated. Umbilical hernias are common. With a study involving Africans, 92% of children had protrusions, 49% of adults, and 90% of pregnant women.