Amniocentesis

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KEY POINTS

• Amniocentesis is a test that may be done during pregnancy to check the health of your baby.
• Your provider will put a thin needle into your belly to get a small amount of fluid from the bag that surrounds the baby.
• The test provides information about your baby and also can help find problems that may need treatment.

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What is amniocentesis?

Amniocentesis is a test that may be done during pregnancy to check the health of your baby. A very thin needle is used to remove a small amount of fluid from the amniotic sac. The amniotic sac is like a bag that surrounds the baby. As the baby grows, the fluid around the baby can be tested in the lab to learn about the health of the baby.

If test results show that your baby does have a problem, your healthcare provider will talk to you about your choices for treatment. The information can help you decide how to manage a pregnancy with a baby affected by the problem.

When is it used?

This test can:

• Detect birth defects caused by some genetic problems, such as Down syndrome or sickle cell anemia. Genes are inside each cell of your body and are passed from parents to children. They contain the information that tells your body how to develop and work.
• Find some problems with the brain or spinal cord, such as spina bifida (the spine has not closed normally) and anencephaly (all or part of the brain is missing)
• Check the baby’s blood type. This is important if the mother has Rh-negative type blood and the father has Rh-positive type blood.
• Check the growth of the baby's lungs to see if the baby will be able to breathe OK if he or she is delivered before the due date
• Check for infection inside the uterus.

This test may be done to check for problems with the baby’s genes when you are 15 to 18 weeks pregnant. If the baby needs to be born early, the test may be done later in your pregnancy to see if the baby’s lungs are strong enough.

How do I prepare for this test?

You usually do not have to do anything to prepare for this test. However, if the test is being done near your due date, your healthcare provider may ask you to avoid eating or drinking anything the day of the test.

Follow any other instructions your healthcare provider gives you.

What happens during the test?

You will have an ultrasound during the test, which uses sound waves to show pictures (imaging) of the uterus and baby. Your belly is cleaned with an antiseptic solution. Your healthcare provider will then use the ultrasound imaging to help guide a thin needle safely through your belly, into the uterus, and to the area where the most amniotic fluid is. Like when you have your blood drawn, you may feel some brief, mild discomfort from the needle. Your provider will use the needle to get a small amount of fluid for lab tests.

If you are pregnant with more than 1 baby, a sample of fluid may be taken with different needles from each baby's amniotic sac.

What happens after the test?

Your pulse, your blood pressure, and the baby's movements will be watched for a brief time after the test. Then you can usually go home. You should rest for 24 hours after the test.

The results of most genetic tests will be available in 1 to 2 weeks. Lung maturity can be determined within 6 hours to 1 day usually. The results of a test for infection may take up to a few days.

Ask your healthcare provider:

• How and when you will get your test results
• How long it will take to recover
• If there are activities you should avoid and when you can return to your normal activities, including when to resume exercise and sexual activity
• How to take care of yourself at home
• What symptoms or problems you should watch for and what to do if you have them, including bleeding, leaking, and cramping

Make sure you know when you should come back for a checkup. Keep all appointments for provider visits or tests.

What are the risks of this test?

Every procedure or treatment has risks. The risk of complications from this test is very low. Some possible risks include:

• You may develop an infection or have bleeding.
• The needle may harm the baby, placenta, or umbilical cord.
• You may have premature breaking (rupture) of the amniotic sac.
• You may have premature contractions or labor.
• You may have an increased risk of miscarriage.

Normal test results do not always mean the baby will be normal. Also, in very rare cases, an abnormal result may not be accurate.

Ask your healthcare provider how these risks apply to you. Be sure to discuss any other questions or concerns that you may have.