Prenatest^®

A screening test differs from medical tests as medical tests are diagnostic and provide the doctor and patient with a definitive result. A diagnostic test shows that the patient either has a type of medical condition or does not have the condition. In a screening test, the result shows only the patient’s risk or chance of having the medical condition. Patients who are at high risk may in fact not have the medical condition. The screening test is one of several factors that help patients decide whether they would like to undergo a definitive diagnostic test.

In the field of prenatal testing, screening is especially applicable since the diagnostic tests for trisomy 21 and trisomy 18 (chorionic villus sampling or amniocentesis) can cause pregnancy complications or in some cases a miscarriage. Therefore, it is not practical to provide diagnostic testing to all pregnant women. By performing the screening test first, patients are provided with a risk that their pregnancy may be associated with trisomy 21 or trisomy 18.

The Prenatest^® Prenatal Screening service will inform you of your risk of carrying a fetus with Trisomy 21 or 18. In the first trimester, the detection rate of Trisomy 21 is 90-95%¹ and the false-positive rate is less than 0.1%². The test measures:

1. Nuchal translucency: The amount of fluid accumulation at the back of the fetal neck. Fetuses affected by certain conditions may have an increased nuchal translucency; and
2. Nasal bone: 70% of fetuses affected by trisomy 21 have an absent nasal bone during the first trimester of pregnancy.

Low-risk results indicate that your risk of having a fetus with Trisomy 21 is lower than the established threshold value of 1/250. This does not guarantee that the fetus is not affected, but it tells you that you are at lower risk

High-risk results indicate that your risk of having a fetus with Trisomy 21 is greater than or equal to the established threshold value of 1/250. However, this does not necessarily mean that your fetus is affected. Your physician or a genetic counsellor will discuss your options with you, including diagnostic testing. Before proceeding with an invasive diagnostic test, patients who have selected the Prenatest Plus option will be offered a non-invasive prenatal test at no additional charge.

Prenatest^® Screening should be performed during the first trimester, between the 11th and 14th weeks of your pregnancy. Follow-up tests may include non-invasive prenatal testing (NIPT), Amniocentesis (Amnio Test), or Chorionic Villi Sampling (CVS Test).