All You Need to Know About Amniocentesis

All You Need to Know About Amniocentesis

What does it test for?

Amniocentesis is a diagnostic test that is most commonly used to determine if your developing baby has certain health conditions, such as birth defects or genetic and chromosomal abnormalities. While screenings may tell you if your baby is more at risk for certain conditions, amniocentesis can tell you whether or not your baby actually has a certain health condition.1 Additionally, amniocentesis may be used for fetal lung testing, diagnosis of a fetal infection or anemia, paternity testing or as treatment if you produce too much amniotic fluid.2

How is it performed?

The test is performed by removing amniotic fluid from the amniotic sac within your uterus. Your health care provider will use an ultrasound to determine the position of your baby and the placenta.1,2 Then, your doctor will sterilize the area and use a long, thin needle to remove a small amount of amniotic fluid.2 The full procedure takes about 45 minutes total.3 After the procedure is complete, your provider will continue to use the ultrasound to ensure your baby’s heart rate is normal.1,2

When is it needed?

Amniocentesis is available for all pregnant women. In fact, the American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women have the choice for prenatal tests, such as amniocentesis.1,4 However, your health care provider is more likely to recommend amniocentesis if you are at an increased risk for having a child with birth defects or genetic and chromosomal conditions.1 If your doctor recommends genetic amniocentesis, the test is performed between 15-20 weeks of gestation.1,2

Amniocentesis is recommended more frequently if you:1

  • Are over the age of 35- the risk for having a baby with a chromosomal abnormality increases as maternal age increases
  • Have a family history for a genetic condition- carrier screenings are available to determine if you or your partner (or both) are carriers for certain conditions that may be passed onto your baby
  • Your prenatal screening results are abnormal- amniocentesis is a diagnostic test that can diagnose a health condition, whereas a screening cannot
  • You have a child with a birth defect or you had a previous pregnancy with a birth defect- the risk of having another pregnancy with a birth defect increases if you have had a previous pregnancy with a defect

How to prepare:

There’s not much physical preparation for an amniocentesis test. However, if you are having the test before 20 weeks of gestation, having a full bladder will help to support your uterus, so make sure you drink plenty of fluids.2 If your test is after 20 weeks of gestation, it is better to have an empty bladder to avoid a puncture.2 Emotionally, it may be comforting to have someone accompany you to your test. Amniocentesis can be scary, especially if you are worried about the outcome of the test. Having a calming presence may help alleviate some of the stress.

What are the risks?

Amniocentesis is generally safe and serious risks and complications are rare.1,3 However, amniocentesis is considered an invasive diagnostic test.3 Miscarriage is considered the primary risk of amniocentesis, but less than 1% of women will have a miscarriage after the procedure.1,3 During the procedure you may experience cramping when the needle enters the uterus or some pressure when the fluid is removed. You may also experience cramping or mild pelvic discomfort after an amniocentesis.2 Typically, your health care provider will instruct you to abstain from exercise or sex for 1-2 days after the procedure.1,2
Although serious risks are rare, if you experience any of the following symptoms, you should contact your health care provider right away:1,2

  • Change in your baby’s movement
  • Vaginal bleeding or fluid leakage
  • Fever
  • Redness and/or swelling where the needle was inserted
  • Intense belly cramps that last more than a few hours

What are the Benefits?

Prenatal genetic testing has many benefits, including but not limited to:5

  • Reassures patients when results are normal
  • Identifies disorders for which prenatal treatment may provide benefit
  • Optimizes fetal outcomes by ensuring the appropriate delivery location and care are being provided for affected babies

REFERENCES: 1. March of Dimes. Amniocentesis. Website. Reviewed May 2017. Accessed November 28, 2018. 2. Mayo Clinic. Amniocentesis. Website. Published November 8, 2018. Accessed November 28, 2018. 3. American Pregnancy Association. Amniocentesis. Website. Reviewed September 2, 2016. Accessed November 28, 2018. 4. American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins – Obstetrics. ACOG Practice Bulletin No. 164: Prenatal Genetic Diagnostic Tests. September 2016. Accessed November 28, 2018. 5. American College of Obstetricians and Gynecologists (ACOG) Committee on Practice Bulletins – Obstetrics. ACOG Practice Bulletin No. 162: Prenatal Diagnostic Testing for Genetic Disorders. Obstetrics & Gynecology. 2016;162:1.—-Obstetrics/pb162.pdf?dmc=1&ts=20181012T2016340336. Accessed November 28, 2018.

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