Amniotic fluid surrounds the baby during pregnancy. Amniocentesis is the removal of a small amount of this fluid for testing.
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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:
- Age: over 35 years at the time of delivery
- Family history of chromosome abnormality
- Family history of inherited disorder
- Family history of neural tube defect—problems in spine and brain growth, such as spina bifida or anencephaly
- Abnormal results from early screening tests for chromosomal abnormalities
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:
- In high-risk pregnancies that may require early delivery
- There is concern for Rh-sensitization pregnancy
Problems from the procedure are rare, but all procedures have some risk. Your doctor will review potential problems, like:
- Bleeding, cramping, and leaking fluid from the vagina
- Mixing of blood if you and your baby have different blood types
- Need for repeat testing
- Harm to the fetus by the needle—Rare
Factors that may increase your risk of complications include:
- Maternal obesity
- Previous abdominal surgery
Be sure to discuss these risks with your doctor before the procedure.
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.
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.
Call Your Doctor
It is important to monitor your recovery. Alert your doctor to any problems. If any of the following occur, call your doctor:
- Signs of infection, including fever and chills
- Nausea or vomiting
- Pain or cramping in your lower abdomen or shoulder
- Vaginal bleeding or a loss of fluid from the vagina
- Redness, swelling, increasing pain, excessive bleeding, or discharge from the amniocentesis site
- New, unexplained symptoms
If you think you have an emergency, call for medical help right away.
American Pregnancy Association http://www.americanpregnancy.org
The Society of Obstetricians and Gynaecologists of Canada http://sogc.org/publications-resources/patient-fact-sheets
Updated April 2006. Accessed March 14, 2014.
Hemolytic disease of the fetus and newborn (HDFN). EBSCO DynaMed website. Available at:
Updated March 6, 2013 Accessed April 30, 2014.
Later childbearing. American College of Obstetricians and Gynecologists website. Available at:
Updated December 2012. Accessed March 14, 2014.
Routine prenatal care. EBSCO DynaMed website. Available at:
Updated March 3, 2014. Accessed March 14, 2014.
The American Congress of Obstetricians and Gynecologists, Invasive Prenatal Testing for Aneuploidy, Practice Bulletin No. 88, December 2007; Reaffirmed 2014.
Last Updated: 4/29/2014