NIPT EDUCATION

Prenatal Screening Tests

Prenatal screening tests are designed to provide information about your baby’s genetic health. By learning more about your screening options, you can make an informed decision about which test is right for you. Your doctor will provide you with more information about your testing options.

Prenatal screening tests:

Assess your risk of certain conditions during pregnancy
Are safe for pregnancy
Are followed by additional testing if a diagnosis is needed
Can be done as early as 10 weeks of pregnancy

Prequel® Prenatal Test

The Prequel® test is a highly reliable test for determining trisomy of chromosomes 21, 18 and 13. It can also provide information on other chromosomes and structural abnormalities (microdeletions and duplications). The test can also be used to determine the sex of the baby and abnormalities in the number of sex chromosomes (X, Y).

In the event of a positive result (abnormality detected) in the Prequel prenatal test, an invasive diagnostic test should be performed subsequently to confirm the results. Depending on the gestational age of the pregnancy, the following methods are available:

Chorionic villus sampling (CVS)

Chorionic villus sampling is an invasive diagnostic procedure in which a sample of fetal placental tissue (chorionic villi) is collected using a long needle under ultrasound guidance. The sample is then analyzed in a genetics laboratory to study the chromosomes. The mother can undergo this procedure between the tenth and thirteenth week of pregnancy. The risk of miscarriage after the procedure varies from 1/140 to 1/4500.

Amniocentesis

The amniotic fluid surrounding the baby is removed with a long needle under ultrasound guidance. The fetal cells in the fluid are then analyzed in a genetic laboratory. The procedure is usually performed between the fifteenth and twentieth week of pregnancy. The risk of miscarriage after amniocentesis varies from 1/160 to 1/9000.

Cordocentesis

Cordocentesis is an invasive procedure in which a sample of fetal blood is taken from the umbilical cord. Its purpose is to establish a de nitive diagnosis when prenatal tests, specialized ultrasound, or amniocentesis have failed to provide an accurate diagnosis, or if the pregnancy is too advanced to perform an amniocentesis. It is rarely used to examine the appearance and number of chromosomes (karyotype). It is performed after the twentieth week of pregnancy and lasts 30 to 60 minutes. Complications can occur in 1-3% of cases.