Amniocentesis is not recommended for all women—mainly due to the fact that the test is invasive and carries a small risk of miscarriage—but it is generally administered to those who are at increased risk for genetic and chromosomal problems. This prenatal screening enables your health care professional to examine fetal cells in the amniotic fluid for any chromosomal abnormalities.
If you are 35 or older when you're due to have your baby, your health care professional will likely discuss the risks of chromosomal abnormalities based on your age and recommend this test. That's because women over 35 have a higher risk of having a baby with Down's syndrome.
An amniocentesis is also recommended if you've already had a child with certain birth defects, or if you have a family or personal history that puts you at risk for certain inherited diseases. You might choose to have this test if you had abnormal blood tests that suggest there might be a problem.
Amniocentesis can diagnose numerous conditions, but only if the lab evaluating the amniotic fluid knows which tests to conduct. These tests are very expensive, so talk with your health care professional about which ones are necessary based on your history and risk factors. It can take anywhere from a few days to a few weeks to get the results.
During an amniocentesis, the doctor inserts a needle through your abdomen into the amniotic sac and removes a small amount of amniotic fluid. The doctor uses ultrasound to guide the needle and avoid inserting it into the placenta.
An amniocentesis has a complication rate of less than 1 percent, but there is a small risk of miscarriage associated with this procedure. The test can be performed on an outpatient basis in a health care professional's office or in a hospital. It's important to choose a doctor with plenty of experience or a center that performs a lot of amnios.
It can be done at any gestational age after 11 weeks, but when it's performed for genetic studies, amniocentesis is usually done between 15 and 17 weeks.
If you are getting an amnio, learn about the risks and benefits for banking your amniotic fluid.
Learn about six other common prenatal tests.