During your pregnancy, your care team may recommend an amniocentesis to test your baby for a wide range of genetic and chromosomal conditions.

An amniocentesis is a prenatal test that uses a sample of amniotic fluid to provide you with important information about your baby’s health, allowing you to plan for their needs after birth.

The test looks for certain genetic and chromosomal conditions as well as brain and spinal defects (known as neural tube defects) that may affect how your baby grows and develops during pregnancy. For example, an amniocentesis can detect the following:

  • Cystic fibrosis
  • Down’s syndrome
  • Muscular dystrophy
  • Sickle cell disease
  • Spina bifida
  • Tay-Sachs disease
  • Trisomy 18

Your pregnancy care team can help you understand:

  • Whether you’re a good candidate for amniocentesis
  • What to expect during the test
  • What the results mean for you and your baby
  • Next steps depending on the results of the test

Our Approach to Amniocentesis

When you’re pregnant, you may have questions about your baby’s health and development along the way. One of the clearest ways to get answers is through an amniocentesis. 

Amniocentesis is not a standard prenatal test like fetal monitoring and ultrasounds. It is more invasive, requires an in-office visit and is done later in your pregnancy, usually during the second or third trimester. 

Our OB/GYNs and midwives typically only recommend an amniocentesis if:

  • You are 35 years old or older
  • You or your partner have a family history of genetic or chromosomal conditions or neural tube defects, like Down’s syndrome or spina bifida
  • You have a prenatal ultrasound that identifies anything unexpected
  • You or your partner carry certain genes or chromosomes that put your baby at a higher risk for conditions like Trisomy 18 or muscular dystrophy
  • The results of a genetic screening test indicate an elevated risk of certain genetic or chromosomal conditions or neural tube defects

Your pregnancy care provider will discuss the risks and benefits of amniocentesis with you. Our goal at MU Health Care is to empower you to decide if the test is right for you based on your needs, preferences and risk factors.

How Accurate is an Amniocentesis?

Amniocentesis is about 99% accurate in detecting genetic and chromosomal conditions and neural tube defects. However, there is a 1% chance of having a false positive, which is when the test incorrectly indicates a condition. 

Additionally, while an amniocentesis can detect a condition, it cannot provide information about how serious the condition is. In other words, amniocentesis cannot determine whether your baby has a mild or severe condition.

Amniocentesis Risks

While amniocentesis is a common prenatal test that thousands of women get every year, there is a small chance of complications. The risks for amniocentesis include: 

  • A one in 300 chance of miscarriage after the procedure, with an increased risk if the test is performed before 15 weeks
  • A small risk of infection inside the uterus after the procedure
  • In very rare cases, amniocentesis can cause some of your baby’s blood cells to enter your bloodstream. This can cause issues for your baby if you are Rh negative and your baby is Rh positive.

Your care team will discuss risk factors with you before your amniocentesis.

Benefits of Amniocentesis

The biggest benefit of an amniocentesis is getting a clear answer about your unborn baby’s health and development. An amniocentesis is one of the most accurate prenatal genetic tests available. If your amniocentesis identifies that your baby has a specific condition, our team can help you determine next steps.

What to Expect with Amniocentesis

Our fetal care specialists will perform your amniocentesis during the second or third trimester of your pregnancy. Here’s what you can expect during your amniocentesis: 

  • A specialist will do an ultrasound of your abdomen to locate your uterus and your baby’s amniotic sac.
  • They’ll then insert and carefully guide a long, hollow needle into your abdomen and the amniotic sac. You may feel a slight sting and some cramping at this point in the procedure.
  • The specialist will use the needle to draw a small amount of amniotic fluid into a syringe. You may feel a tugging sensation as your doctor fills the syringe.
  • Once the needle is removed, the puncture wound usually closes on its own and you can resume normal activities. Some patients experience mild cramping and minimal vaginal bleeding, but these typically resolve quickly.

After the procedure, your care team will send the amniotic fluid to a lab for testing.

Amniocentesis Results

Our genetic specialists will test your amniotic fluid sample and contact you with your results. 

If you receive results that indicate that your baby has a genetic or chromosomal condition or a neural tube defect, your care team will be by your side and help you understand your options.

Examples of potential next steps include: 

  • Additional genetic testing and counseling
  • Additional testing, such as fetal MRI
  • Referral to our Fetal Intervention Center, which focuses on treating unborn babies who have fetal complications
  • Referral to a maternal fetal medicine doctor who specializes in high-risk pregnancy
  • Referral to resources for emotional and social support

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