At first glance amniocentesis seems to have many benefits. But when you take a closer look the test may not be the best option for you and your baby.
What's it For?
Amniocentesis is a prenatal test given to assess if an unborn baby has any genetic abnormalities. It can test for hundreds of different disorders including almost all chromosomal abnormalities. Down Syndrome is one of these. Amnios are very good at indicating these complications – they have a 99% accuracy rate.
Amniocentesis can also be used to screen for neural tube defects such as spina bifida and anencephaly. In addition, it can screen for other genetic disorders. These include disorders more common in certain ethnic groups such as Tay-Sachs disease and sickle cell anemia.
You can't find all birth defects with an amnio. Congenital abnormalities (those present at birth) such as a cleft palate or club foot aren't detected by the test. An abnormal test may give indication to check for these via ultrasound.
How is it Done?
Amniocentesis is a major procedure – plan to have the entire day to rest afterwards. The steps are:
- Lie on a table and have an ultrasound to determine your baby's position. The technician or doctor performing the procedure is guided by ultrasound.
- A thin needle is inserted through your abdomen and down through the uterus, amniotic sac, and into the amniotic fluid. The amnio is so named because the needle draws a small sample of fluid up to be collected and analyzed.
- The sample is sent to a laboratory where it has to be cultured for 2-3 weeks.
What are the Side Effects?
Some of the side effects include cramping and bleeding. Some women experience severe cramping. Rest and relax after the procedure. Sometimes amniotic fluid may leak.
There's a risk of miscarriage after amniocentesis. This risk is generally thought to be between 1-3%, which is significantly higher than if no amniocentesis is performed. The March of Dimes reports the risk to be 1 in 200 babies lost after the procedure.
There are major emotional side effects as well. The procedure is meant to bring peace of mind, but many women find they feel anxious and irritable while they wait on the test results.
Speaking to someone about your feelings is helpful, especially another mom who has had the same experience.
When Should Amniocentesis Be Done?
A much less invasive test called the Triple Screen, or the Quad Screen, is now available to all women early in the second trimester. This test gives a good indication if an amnio should be performed.
Even the American College of Obstetrics and Gynecology is recommending that the Triple or Quad Screen be done before amniocentesis. All women over age 35 used to be routinely offered amniocentesis, even though most would come back just fine. The Triple or Quad Screen offers a safe method to see if the more invasive test may be warranted.
Women who have a family history of genetic or chromosomal abnormality, or who have given birth to a child with an abnormality should review the pros and cons of amniocentesis in depth with their midwife or doctor.
Personal risk is always the best way to decide if you should have an invasive procedure such as amniocentesis performed. Your midwife or doctor can help you weigh any risks versus benefits. You should do your own research as well, and seek second opinions if you need them.