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Amniocentesis

Test Overview

Amniocentesis is a test to look at the fluid that surrounds your baby (fetus, Opens dialog) in the uterus, Opens dialog. Amniotic fluid, Opens dialog has cells and other substances that can give clues about the health of your fetus.

For this test, a needle is put gently through your belly into your uterus. About 30 mL (2 Tbsp) of fluid is taken out and looked at.

This test may be done between weeks 15 and 20 to look at the baby's genes. It can also be used later in pregnancy.

Amniocentesis for genetic testing

Amniocentesis is often done around week 16 to see if a fetus has certain genetic conditions. It can also tell the sex of a fetus and help find certain neural tube defects.

Amniotic fluid has cells that have been shed by your growing fetus. The cells are checked for the number and size of chromosomes, Opens dialog. This can show if there are any problems that put the baby at risk for certain conditions, such as Down syndrome, Opens dialog. But this test can't find many common birth defects, such as cleft lip, Opens dialog, cleft palate, Opens dialog, or heart problems.

Testing is most often done as soon as possible so women and their families have time to think about their options.

Amniocentesis in late pregnancy

This test may also be done later in pregnancy if your doctor thinks you may have an infection of the amniotic fluid (chorioamnionitis).

Information about Amniocentesis

Adaptation Date: 07/04/2025

Adapted By: Alberta Health Services

Adaptation Reviewed By: Alberta Health Services

Adapted with permission from copyrighted materials from Ignite Healthwise, LLC (Healthwise). This information does not replace the advice of a doctor. Healthwise disclaims any warranty and is not responsible or liable for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

Information about Amniocentesis

Adaptation Date: 07/04/2025

Adapted By: Alberta Health Services

Adaptation Reviewed By: Alberta Health Services