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Amniocentesis

Medically reviewed by Drugs.com. Last updated on Oct 7, 2022.

Overview

Amniocentesis is done to remove amniotic fluid and cells from the uterus for testing or treatment. Amniotic fluid surrounds and protects a baby during pregnancy.

Amniocentesis can provide useful information about a baby's health. But it's important to know the risks of amniocentesis — and be prepared for the results.

Amniocentesis

Amniocentesis is a test done during pregnancy. During amniocentesis, an ultrasound wand (transducer) is used to show a baby's position in the uterus on a monitor. A sample of amniotic fluid, which contains fetal cells and chemicals produced by the baby, is then taken for testing.

Why it's done

Amniocentesis can be done for a number of reasons:

Genetic amniocentesis

Genetic amniocentesis can provide information about the baby's genes. Generally, genetic amniocentesis is offered when the test results might affect how to manage the pregnancy.

Genetic amniocentesis is usually done between weeks 14 and 20 of pregnancy. Amniocentesis done before week 14 of pregnancy might lead to more complications.

Reasons to consider genetic amniocentesis include:

Risks

Amniocentesis carries risks, which occur in approximately 1 in 900 tests. They include:

Remember, genetic amniocentesis is usually offered to pregnant people for whom the test results might greatly affect how they manage the pregnancy. The decision to have genetic amniocentesis is yours. Your health care provider or genetic counselor can give you information to help you decide.

How you prepare

Your health care provider will explain the procedure and ask you to sign a consent form. Consider asking someone to accompany you to the appointment for emotional support or to drive you home afterward.

What you can expect

Amniocentesis is usually done in an outpatient obstetric center or a health care provider's office.

During the procedure

First, a health care provider will use ultrasound to pinpoint where the baby is in the uterus. You'll lie on your back on an exam table with your belly showing. Your health care provider will apply a gel to your belly and then use a small device known as an ultrasound transducer to show your baby's position on a monitor.

Next, your health care provider will clean your abdomen. A numbing medication generally isn't used. Most people report only mild soreness during the procedure.

Guided by ultrasound, your health care provider will insert a thin, hollow needle through your stomach wall and into the uterus. A small amount of amniotic fluid is drawn into a syringe. The needle is then removed.

You need to lie still while the needle is put in and the amniotic fluid is taken out. You might feel a sting when the needle enters your skin. You might feel cramping when the needle enters your uterus.

After the procedure

After amniocentesis, your health care provider will continue using the ultrasound to monitor your baby's heart rate. You might have cramping or mild pelvic pain after an amniocentesis.

You can return to your regular activities after the test.

The sample of amniotic fluid will be looked at in a lab. Some results might be available within a few days. Other results might take several weeks.

Contact your health care provider if you have:

Results

Your health care provider or a genetic counselor will help you understand your amniocentesis results.

For genetic amniocentesis, test results can rule out or diagnose some genetic conditions, such as Down syndrome. Amniocentesis can't identify all genetic conditions and birth defects.

If amniocentesis suggests that your baby has a genetic or chromosomal condition that can't be treated, you might face hard decisions. Seek support from your health care team and your loved ones.

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