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Reasons for Procedure

Amniocentesis is most often done to see if there is an abnormality in your baby's genes (DNA). It can also be done to see if your baby is developing correctly. Later in pregnancy, it can be done to determine the maturity of your baby's lungs.
Factors that indicate that you may need this procedure include:
Depending on your risk factors, cells in the amniotic fluid are tested for:
  • Chromosome abnormalities. The results are usually ready within 14 days. Missing or extra chromosomes lead to physical birth defects and intellectual disability. Down's syndrome is one example.
  • Inherited genetic diseases—Test results are usually ready in 1-5 weeks. Examples include:
Amniocentesis may also be done:
  • To determine whether the baby's lungs are mature
  • In high-risk pregnancies that may require early delivery
  • There is concern for Rh-sensitization pregnancy

What to Expect


You may be given a local anesthesia. This numbs a small area in the abdomen where the needle will be placed.

Description of the Procedure

First, an ultrasound will be done. This will help to choose a safe spot to insert the needle. Your abdomen will be cleaned. Next, a very thin needle will be inserted through your abdomen into your uterus. A few teaspoons of amniotic fluid will be removed. After the needle is removed, the doctor will make sure that your baby's heartbeat is normal. In most cases, an ultrasound will be used throughout the procedure.

How Long Will It Take?

About 45 minutes.

Will It Hurt?

You may feel cramping when the needle enters your abdomen. You may also feel pressure when the fluid is withdrawn.

Post-procedure Care

A test showing a healthy baby is ideal. But, you will need to be prepared if the results show otherwise. If the test shows that your baby may have a genetic disorder, you may need to make tough decisions regarding your pregnancy. If you do continue with the pregnancy, then you will need to address your child's special needs. Your doctor can help you understand the pros and cons of having this test. Your doctor will work with you on options that are best for you after you know the results.


American Congress of Obstetricians and Gynecologists

American Pregnancy Association



Canadian Women's Health Network

The Society of Obstetricians and Gynaecologists of Canada



The American College of Obstetricians and Gynecologists, Invasive Prenatal Testing for Aneuploidy, Practice Bulletin No. 88, December 2007; Reaffirmed 2009.

Chorionic villus sampling (CVS). American Pregnancy Association website. Available at: Updated April 2006. Accessed March 14, 2014.

Later childbearing. American College of Obstetricians and Gynecologists website. Available at: Published December 2012. Accessed October 2, 2012.

Screening and monitoring during pregnancy. EBSCO DynaMed website. Available at: Updated March 3, 2014. Accessed March 14, 2014.

Hemolytic disease of the newborn. EBSCO DynaMed website. Available at: Updated March 6, 2013 Accessed April 30, 2014.


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