A hernia is where an internal part of the body pushes through a weakness in the muscle or surrounding tissue wall.

Your muscles are usually strong and tight enough to keep your organs and intestines in place, but a hernia can develop if there are any weak spots.

Umbilical hernias are very common in infants and young children, particularly in babies born prematurely.

An umbilical hernia appears as a painless lump in or near the belly button (navel). 

It may get bigger when laughing, coughing, crying or going to the toilet and may shrink when relaxing or lying down.

In many cases, the umbilical hernia goes back in and the muscles reseal by the time a child is 4 or 5 years old.

Umbilical hernias can also develop in adults. Without treatment, the hernia will probably get worse over time.

For information on other types of hernia, see:

• inguinal hernia
• femoral hernia
• hiatus hernia

During pregnancy, the umbilical cord passes through an opening in the baby's abdomen (tummy). This opening should close shortly after birth, but in some cases the muscles don't seal completely.

This leaves a weak spot in the surrounding muscle wall (abdominal wall). An umbilical hernia can develop when fatty tissue or a part of the bowel pokes through into an area near the navel.

In adults, factors that can contribute to developing an umbilical hernia include:

• being overweight or obese
• straining while you are lifting or moving heavy objects
• having a persistent heavy cough
• having a multiple pregnancy such as twins or triplets

If necessary, umbilical hernias can be treated with surgery to push the bulge back into place and strengthen the weakness in the abdominal wall.

This operation may be recommended for your child if the hernia is large or hasn't disappeared by the time they reach 4 or 5 years old.

You'll usually be advised to wait for your child to reach this age because the operation isn't essential unless there are complications. The risk of your child developing complications is very low.

Surgery is recommended for most adults with an umbilical hernia because the hernia is unlikely to get better by itself when you're older and the risk of complications is higher.

Complications that can develop as a result of an umbilical hernia include:

• obstruction – where a section of the bowel becomes stuck outside the abdomen, causing nausea, vomiting and pain
• strangulation – where a section of bowel becomes trapped and its blood supply is cut off; this requires emergency surgery within hours to release the trapped tissue and restore its blood supply so it doesn't die

Surgery will get rid of the hernia and prevent any serious complications, although there's a chance of it returning after the operation.

An umbilical hernia repair is a relatively simple procedure that normally takes about 20 to 30 minutes. General anaesthetic is usually used so there's no pain while the operation is carried out.

In children, the weak spot in the abdominal wall is usually closed with stitches. If the hernia is large or in adults, a special mesh may be used to strengthen the area instead.

You or your child should be able to go home on the same day as the operation. You may feel a bit sore and uncomfortable while you recover. 

You may need to limit strenuous activities for a few weeks after the operation, and taking some time off school or work is often recommended. Most people are able to return to all their normal activities within 2 weeks of surgery.

Read more about:

• how an umbilical hernia repair is performed
• recovering from an umbilical hernia repair

Complications from an umbilical hernia repair are uncommon, but can include:

• infection of the wound – it may appear red, have a yellow discharge and be painful or swollen
• bleeding
• rupture of the wound
• the hernia returning