Prenatal Tests 101 Amniocentesis TestDuring your pregnancy you’re bound to learn an entirely new vocabulary.  One word your doctor is sure to use is amniocentesis.  This word refers to a fairly common test performed to determine the health of your baby.  To perform this test, a doctor or nurse removes a small quantity of amniotic fluid using a thin, hollow needle.  Using an ultrasound to help guide the needle, the needle is inserted through the abdomen into the uterus to collect amniotic fluid.  After the fluid is collected, it is sent to a lab and a technician runs a variety of tests.

Amniocentesis Basics
This test is typically performed before the 20th week of pregnancy.  Most amniocentesis test procedures fall between the 15th and 18th weeks.  There are risks associated with this test, though they are rare.  Amniocentesis tests carry a less than 1% risk of miscarriage.  Even rarer risks include infection and preterm labor.  Before undergoing this test, your doctor or midwife will direct you towards genetic counseling to fully understand the procedure and what it may potentially reveal.  The genetic counselor should fully explain the risks as well as the benefits.  After you have all the facts, it’s up to you as to whether you’d like to proceed and schedule the procedure.

Why Have an Amniocentesis?
First, this prenatal test can accurately determine a baby’s sex.  If your little one is camera shy and your technician is unable to visually determine a gender, an amniocentesis exists as an excellent option.  Second, an amniocentesis test can provide a variety of information specifically about birth defects.  Your healthcare professional may recommend getting this test for several reasons, including any of the following:

  • If you are over 35 years of age
  • If you have a familial history of birth defects
  • If you previously conceived a child with birth defects
  • If an ultrasound reveals an abnormality

Which Birth Defects can an Amniocentesis Reveal?
It’s important to keep in mind that no test is infallible.  In addition, an amniocentesis cannot test for all birth defects; however, it is a reliable test for the following birth defects:

  • Anencephaly
  • Cystic Fibrosis
  • Down Syndrome
  • Sickle Cell Disease
  • Spina Bifida
  • Tay-Sachs Disease

What Can I Expect?
On the day of the procedure, the doctor will use an ultrasound to locate the baby’s position.  Then, he or she will rub antiseptic on your abdomen.  You can request a local anesthetic to numb the area if you’d like.  Then, the doctor inserts a long needle into the uterus.  He or she will withdraw a small amount of amniotic fluid and send it to be tested.  Experiencing minor cramps or general discomfort after the procedure is common.Lab results are usually available within 2-3 weeks.  Your doctor should call when they are available to discuss the lab’s findings with you and your birth partner.

Because there are risks involved in this procedure, it’s important to weigh the pros against the cons before scheduling one.  Talk with your birth partner as well to decide if knowing about birth defects is something you’d both like to know as soon as possible.  The doctor-recommended genetic counselor will be able to answer any questions specifically about the types of birth defects an amniocentesis test  can test for as well as how certain birth defects would affect your baby.  Remember: an amniocentesis is an optional test; the decision is up to you. You can also find more reading about this test here.