An umbilical hernia is a protrusion of the peritoneum and fluid, omentum or a portion of abdominal organ(s) through the umbilical ring -- which is the fibrous and muscle tissue around the navel (belly-button).

An umbilical hernia in an infant is caused by the incomplete closure of the umbilical ring (muscle), through which the umbilical blood vessels passed to provide nourishment to the developing fetus.

The hernia generally appears as a soft swelling beneath the skin that often protrudes when the infant is upright, or with crying or straining. Depending on the severity, the area of the defect can vary from less than 1 to more than 5 centimeters in diameter.

Small (less than 1 cm) hernias usually close spontaneously without treatment by age 3 to 4 years. Those that do not close may require surgery. Umbilical hernias are usually painless.

Umbilical hernias are common in infants. The exact incidence is unknown, but may be as high as 1 in 6 infants.

Umbilical hernias occur slightly more frequently in infants of African American descent. The vast majority of umbilical hernias are not related to any disease condition. However, umbilical hernias can be associated with rare diseases, such as mucopolysaccharide storage diseases, Beckwith-Wiedemann syndrome, Down syndrome, and others.

• A soft protrusion over the umbilicus
• May be flat when infant is on his back and quiet, but protrudes when upright, crying, or straining

A physical examination reveals the hernia.

Usually, no treatment is required unless the defect persists past the age of 2 years. In extremely rare cases, bowel or other tissue can protrude and become strangulated (lack of blood flow to a section of bowel). This is an emergency requiring surgery.

Most umbilical hernias resolve without treatment by 2 years of age. Those that persist are usually successfully treated by surgery.

Strangulation of bowel tissue is serious, and requires immediate surgery (rare).

Call your health care provider, or go to the emergency room if abdominal pain develops in an infant with an umbilical hernia, or if the hernia becomes tender, swollen, or discolored -- particularly if signs of peritonitis or shock also develop.

There is no known prevention. Taping or "strapping" and umbilical hernia will not cause it to go away.