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What is amniocentesis?

Amniocentesis is a test done to check the health of your baby while you are pregnant. Your baby grows in your uterus, in a special bag of waters called the amniotic sac. The fluid in this sac is tested to check for different kinds of problems.

When is it used?

When amniocentesis is used to check for genetic problems, it is done when you are 15 to 18 weeks pregnant.

It may be a good idea to have this test done if:

• You are over age 35.
• Other prenatal tests show there might be a problem.
• You have had a child born with a defect in the spinal cord or brain, or a genetic problem.
• You or your baby's father have a history of genetic problems.
• You have had three or more miscarriages.

This test may also be done later in pregnancy if the baby needs to be born early for some reason. It tests how well the baby's lungs will work after birth. It can also be used to check for an infection in your amniotic fluid.

How do I get ready for amniocentesis?

You may need to drink a lot of water before it is done. It helps to have a full bladder. Be sure to follow any directions your health care provider gives you.

What happens during the test?

The doctor cleans your abdomen, and may numb the skin. A long needle is put through your abdomen and into the uterus. You may feel some discomfort. The doctor uses ultrasound to help guide the needle away from the baby and to where the most fluid is. He or she takes some fluid out and sends it to the lab.

What happens afterwards?

You and the baby will be checked for a little while. Then you can go home. You should rest for about 24 hours afterwards.

How long does it take to hear the results of the test?

• If your baby is being tested for genetic problems, you should hear the results in 1 to 3 weeks.
• If your baby's lungs are being tested, you should hear in 1 or 2 days.

How does this test help?

It can help check for:

• Genetic problems in the baby, such as Down syndrome.
• Birth defects such as spina bifida.
• Infection in the amniotic fluid.
• How well the baby's lungs will work.

What are the problems with having this test done?

Only about 1 out of every 100 women have any problems at all. But it is important to know what could happen. Amniocentesis can cause:

• Too much blood loss.
• Infections.
• Harm to the baby, placenta, or cord from the needle.
• The bag of waters to break too early.
• Early labor or contractions.
• Miscarriage. (Less than 1 in 200 women have a miscarriage because of the amniocentesis.)

What should I watch for after the test?

Call your health care provider right away if:

• You start having contractions or severe cramping. (It is normal to have some cramping for a short time.)
• You have bleeding or any discharge from the vagina that goes on and on. (It is normal to have a little spotting or leaking at first.)
• You get a fever.
• You have any changes that worry you.

Call your provider during office hours if:

• You have questions about the test or its results.
• You want to make another appointment.