What is Prenatal Testing?


29-Apr-2014

There is much information to absorb at your booking visit, so we ask you to consider some issues before you arrive. There are screening tests available now that predict the chance of your baby having particular genetic or chromosomal conditions that may seriously interfere with quality of life. 

For some time we have offered Combined First Trimester Screening for Down’s Syndrome (trisomy 21).  This is done through a blood test at approximately 10 weeks and an ultrasound scan at 12 weeks.  Cell Free DNA or Non Invasive Prenatal Testing (NIPT) is a new option in prenatal screening and testing for Down's Syndrome and four other chromosomal abnormalities. It is a blood test which analyses fetal DNA circulating in maternal blood.  Testing can be done any time after 10 weeks.  It is possible to have NIPT done as first line test at 10 weeks but this does not replace 12 week ultrasound and is not as detailed as the information obtained from invasive testing such as Chorionic Villous Sampling (CVS) or Amniocentesis.  It is also possible to use this test as a non-invasive way of excluding Down's Syndrome if the Combined First Trimester Screening result is high risk.

Some genetic tests are done on the parents to see if they are carriers of a condition, and this testing should ideally be done pre-pregnancy, or as soon as you decide you want to undertake it. This includes a new reproductive genetic carrier testing that will test for carrier status of three common inherited conditions: cystic fibrosis (CF), fragile X syndrome (FXS) and spinal muscular atrophy (SMA).

We will send out more information regarding these tests before your first visit.  Alternatively, you can visit Victorian Clinical Genetics Services website for additional reading.