An umbilical hernia occurs when part of the intestine protrudes through an opening in the abdominal muscles. Umbilical hernia is a common and typically harmless condition. Umbilical hernias are most common in infants, but they can affect adults as well. In an infant, an umbilical hernia may be especially evident when the infant cries, causing the baby’s bellybutton to protrude. This is a classic sign of an umbilical hernia.

Many umbilical hernias close on their own by age 1, though some take longer to heal. To prevent complications, umbilical hernias that don’t disappear by age 3 or those that appear during adulthood may need surgical repair.

An umbilical hernia creates a soft swelling or bulge near the navel (umbilicus). If your baby has an umbilical hernia, you may notice the bulge only when he or she cries, coughs or strains. The bulge may disappear when your baby is calm or lies on his or her back.

Umbilical hernias in children are usually painless. Umbilical hernias that appear during adulthood may cause abdominal discomfort.

During pregnancy, the umbilical cord passes through a small opening in the baby’s abdominal muscles. The opening normally closes just after birth. If the muscles don’t join together completely in the midline of the abdomen, this weakness in the abdominal wall may cause an umbilical hernia at birth or later in life.

In adults, too much abdominal pressure can cause an umbilical hernia. Possible causes in adults include:

• Obesity
• Multiple pregnancies
• Fluid in the abdominal cavity (ascites)
• Previous abdominal surgery

Umbilical hernias are most common in infants — especially premature babies and those with low birth weights. Black infants appear to have a slightly increased risk of umbilical hernias. The condition affects boys and girls equally.

For adults, being overweight or having multiple pregnancies may increase the risk of developing an umbilical hernia. This type of hernia tends to be more common in women in their 50s or 60s.

For children, complications of an umbilical hernia are rare. Complications can occur when the protruding abdominal tissue becomes trapped (incarcerated) and can no longer be pushed back into the abdominal cavity. This reduces the blood supply to the section of trapped intestine and can lead to umbilical pain and tissue damage. If the trapped portion of intestine is completely cut off from the blood supply (strangulated hernia), tissue death (gangrene) may occur. Infection may spread throughout the abdominal cavity, causing a life-threatening situation.

Adults with umbilical hernia are somewhat more likely to experience incarceration or obstruction of the intestines. Emergency surgery is typically required to treat these complications.

An umbilical hernia is diagnosed during a physical exam. Sometimes imaging studies — such as an abdominal ultrasound or X-ray — are used to screen for complications.

For children, surgery is typically reserved for umbilical hernias that:

• Are painful
• Are bigger than 1.5 centimeters in diameter (slightly larger than a 1/2 inch)
• Don’t decrease in size after six to 12 months
• Don’t disappear by age 3
• Become trapped or block the intestines

For adults, surgery is typically recommended to avoid possible complications — especially if the umbilical hernia gets bigger or becomes painful.

During surgery, a small incision is made at the base of the bellybutton. The herniated tissue is returned to the abdominal cavity, and the opening in the abdominal wall is stitched closed. In adults, surgeons often use mesh to help strengthen the abdominal wall. Recurrences are unlikely.