Genetic Testing For Down Syndrome

If you are in your first trimester of pregnancy, which is between one and twelve weeks, you may be scheduled for an upcoming sonogram. There are many reasons why your OB/GYN will want you to undergo this type of testing. You may be experiencing concerns about undergoing the sonogram, but it is very safe and will cause no harm to you or your baby. This non-invasive test is very commonly used to detect pregnancy, determine the baby’s actual, gestational age and the mother’s due date. All of these determinations are very important for you and your baby. The obstetrician also needs the information so that he will be able to follow your pregnancy and the baby’s growth in preparation for your labor and delivery.

 

The sonogram will be repeated again in your second (12-24 weeks) and third (24-40 weeks) trimesters. During these testing dates the obstetrician will be looking for many different things including:

 

-Down Syndrome & Other Congenital Defects

-Monitor Amniotic Fluids

-Confirm Multiple Pregnancies & Baby’s Sex

-Look For Placenta Previa & Placenta Abruption

-Fetus Structural Abnormalities & Sufficient Blood Flow To Fetus

 

A sonogram can also be used, during a more evasive testing, amniocentesis to guide the needle, which is normally ordered, during the second trimester. Amniocentesis involves extracting amniotic fluid from the amniotic sac, which surrounds the fetus. Your obstetrician may order this test, if your sonogram appears abnormal.

The amniotic fluid contains fetal DNA, which can be tested for chromosomal anomalies such as Down Syndrome and Infant Respiratory Distress Syndrome. There are risks to having this test, but if you truly want to find out, if your child has a congenital defect or respiratory disorder, you will be forced to accept the risks, which includes miscarriage (1-300 and 1-500 per Mayo Clinic), leaking amniotic fluid, infection, and needle injury.

 

Chromosome Analysis

A Karyotype laboratory test involves collecting 3-5 ml of whole blood from the mother. This is a fairly non-invasive test that may detect common, chromosome abnormalities. The results normally takes about seven to ten days and your obstetrician will contact, you if the results are abnormal and may request additional tests to determine a true diagnosis. This test is also used to detect the baby’s gender, which can be performed in the first trimester with successful results.

NT Screening

NT Screening

NT Screening or Nuchal Translucency Screening is a special type of ultrasound that is normally performed between 11-14 weeks gestation. Nuchal translucency is the detection of a collection of fluid under the skin behind the fetal neck. It is about 80% affective in detecting Trisomy 13, 18, and 21 Down Syndrome, with a low 5% false positive rate. Again, your obstetrician may request further testing to help make the actual diagnoses of Down Syndrome. This test should be combined with a maternal blood test, which will measure the pregnancy protein or PAPP-A. If the results show a low level of the pregnancy protein, it can potentially mean that the risk for genetic abnormalities and heart defects are significantly higher.

 

Controversies Related To Pre-Screenings

Parents are beginning to fight for more screenings to detect genetic diseases. These screenings can detect the changes in genes, chromosomes, and pregnancy protein, which could lead to genetic conditions. Genetic testing can also help improve the life expectancy of newborns that have been diagnosed with a congenital or heart defect and genetic abnormality. Not only will this testing help diagnose congenital disorders, but it can also help the parents come to term with the diagnoses, before the baby is born. Many health insurance companies are refusing to cover the costs of the genetic testing, because some of them are so expensive. Should the newborn’s health outweigh the costs?