Down Syndrome Non-Invasive Screening Tests

Amniocentesis is a procedure that involves inserting a long needle into a pregnant woman's abdomen to obtain a sample of the amniotic fluid that surrounds the baby.The amniotic fluid can be tested for many different abnormalities such as cystic fibrosis, neural tube defects, and Down syndrome.Although amniocentesis is considered one of the only truly definitive ways of determining Down syndrome it carries a risk of miscarriage of about 1 in 200 and it can only be performed between the 15th and 18th week of pregnancy for accurate results.Women who might choose to abort a fetus with Down syndrome will already be into their second trimester by the time they obtain the results and abortion becomes much riskier to the mother at this time.

Another invasive test that is performed earlier to give the mother more options is called chorionic villus sampling.This test can be performed only between the 10th and 12th week of pregnancy and involves removing a small piece of the placenta by inserting a thin tube through the vagina and cervix or by way of a long needle through the woman's abdomen guided by ultrasound.This test carries an even higher risk of miscarriage than an amniocentesis at about 1 in 100 tests resulting in miscarriage.

For women who are not willing to put their unborn child at risk with these invasive tests there are now some non-invasive options that can be used in conjunction with each other to determine the odds of Down syndrome without risk of miscarriage.

The nuchal translucency test is the newest screening process available for pregnant women.Nuchal translucency can be performed when a woman is between ten and fourteen weeks of gestation and consists of an ultrasound test that measures the thickness of the nuchal fold that is located in the back of the baby's neck.Babies that have Down syndrome will normally have thicker nuchal folds.The nuchal translucency test is not a definitive diagnostic tools but it can give you an idea of your risk factor for the disease.With an eighty percent accuracy for detecting the risk of Down syndrome the nuchal translucency test can give women peace of mind without risking the life of her unborn baby.If the nuchal translucency test shows an increased risk of Down syndrome more invasive tests can still be performed.

Often two blood tests are given in conjunction with the nuchal translucency test called PAPP-A or pregnancy associated plasma protein - A, and free BHCG or free-beta human chorionic gonadotropin.These blood tests are performed from samples of blood extracted from a pin prick in the mother's finger and the results are used along with the nuchal translucency results to formulate an adjusted risk number for Down syndrome.For example, if your original risk for Down syndrome was 1 in 300 it could be reduced by a favorable test result to 1 in 1000 or be increased by an unfavorable result to 1 in 50.These risk results can help pregnant women make a more informed choice when deciding whether to risk miscarriage with an invasive test.

Risk factors can further be adjusted later in pregnancy with what is commonly called the "˜triple screen test'.The triple screen test can be given up to the 21st week of pregnancy and checks for levels of AFP, oestriol, and human chorionic gonadotrophinthat can help determine if a fetus has Down syndrome or neural tube defects.The triple screen test is a simple blood test.

Ask your doctor or obstetrician about your options for these non-invasive forms of testing if you are uncomfortable with the risk factors of amniocentesis and chorionic villus sampling.Nuchal translucency and the accompanying blood tests are not covered by all insurance companies so you may want to weigh the option of paying for these tests yourself in order to obtain peace of mind with no risk to your baby.