Amniocentesis prenatal test


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Amniocentesis is a prenatal test used to diagnose certain birth defects and genetic conditions.
Genetic conditions are health conditions and birth defects that are passed down to a baby from mom and dad. They may cause health problems for a baby.

Amniocentesis is different from another prenatal test called chorionic villus sampling (CVS). Talk to your health care provider about having an amniocentesis, CVS or other prenatal tests.

Amniocentesis may be recommended if you are at risk for having a baby with a birth defect.

During an amniocentesis, your physician takes a small sample of amniotic fluid, it is fluid that surrounds your baby in the womb. The sample is used to check your baby’s health.

It’s best to have an amniocentesis in the second trimester between 15 and 20 weeks of pregnancy. Amniocentesis before 15 weeks is no longer recommended because it has a higher risk of miscarriage and other complications. A third-trimester amniocentesis can find infections in your uterus (womb) or check to see if your baby’s lungs are developed enough for early birth.

What are some reasons for having an amniocentesis?

These risks include:
  • Being 35 or older. The risk of having a baby with certain birth defects, such as Down syndrome, increases as you get older.
  • Having a previous child or pregnancy with a birth defect. If you had a child or a pregnancy with a birth defect in the past, you may be offered testing.
  • Abnormal screening test results. A screening test is usually a blood test that checks to see if you or your baby is more likely than others to have a certain health condition. It’s different from a diagnostic test that tells you if you do or do not have a certain health condition. If you have abnormal results from a screening test, you will be offered amniocentesis. Most babies with abnormal screening test results are born healthy.
  • Family history of a genetic condition. If you, your partner, or a member of either of your families has a genetic condition, such as cystic fibrosis or sickle cell disease, you may want to have an amnio. to top

 How is the test done?

Amniocentesis takes a few minutes.

First, your physician asks you to lie flat on your back. He/she uses ultrasound to find your baby, the placenta and pockets of amniotic fluid. Physician then cleans your belly with an antibacterial liquid that destroys germs on your skin.

Next, using ultrasound as a guide, your physician puts a thin needle through your belly and uterus into the amniotic sac. He uses the needle to remove about 1 to 2 tablespoons (1 ounce) of fluid.

Once the fluid sample is taken, your physician uses the ultrasound to check that your baby’s heartbeat is healthy.

The amniotic fluid sample is sent to a lab, where it is examined and tested. In the lab, your baby’s cells are separated from the amniotic fluid. If your baby is being tested for genetic problems, the cells are grown for about 10 to 12 days at the lab so that there are enough to check for problems. Test results usually are available within 2 weeks.

The lab may test your baby’s amniotic fluid for proteins like alpha fetoprotein (AFP). Measuring the amount of AFP can check if your baby has neural tube defects (NTDs). The neural tube is the part of a developing baby that becomes the brain and spinal cord. AFP levels are often higher if your baby has an NTD. AFP test results usually are available in a few days.to top

Are there any risks to having an amniocentesis?

Some women find that having an amniocentesis is painless. Others feel cramping when the needle enters the uterus, or pressure when the fluid is removed. 1 to 2 percent of women have cramping, spotting or leaking amniotic fluid after the test. Your physician may tell you to avoid intense activity and take it easy for the rest of the day.

Serious complications from amniocentesis are rare. However, the test does involve a small risk of miscarriage. Less than 1 percent have a miscarriage after amniocentesis.to top

What happens after the test?

In most cases, amniocentesis results show that a baby is healthy and without birth defects. If the test shows that your baby does have a birth defect, talk to your physician about your options. For example, your baby may be able to be treated with medicines or even surgery before birth. Or there may be treatments or surgery he can have after birth. Knowing about a birth defect before birth may help you get ready emotionally to care for your baby. You also can plan your baby’s birth with your health care provider to make sure he/she gets any special care he/she needs right after being born.to top