Man and woman studying a report

The Victorian Clinical Genetics Services (VCGS), which is based at Murdoch Children's Research Institute, has launched a new non-invasive prenatal test (NIPT), which is called percept™. VCGS is a not-for-profit provider of a comprehensive range of clinical and laboratory genetics services.

Below, VCGS Associate Genetic Counsellor Justine Elliott answers some common questions about the test.

What is the percept™ prenatal test?

Prenatal screening provides information about the health of a baby during pregnancy. The percept™ prenatal test uses cell free fetal DNA (cffDNA) found in the mother’s blood to identify the most common chromosome conditions that may affect pregnancies.

Baby diagram percept™ prenatal test

What will the test tell me? What conditions are screened for?

percept™ is an advanced screening test that can identify pregnancies at high risk of Down syndrome (trisomy 21), Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13). A trisomy is caused by three copies of a chromosome, instead of the usual two, and can cause varying levels of intellectual and physical disability.

percept™ will also identify some conditions affecting the sex chromosomes (X and Y), such as monosomy X (45, X).

Find out more about these conditions here.

What does the test involve?

percept™ involves a simple, single blood sample taken from the mother’s arm. It can be performed as early as 10 weeks of pregnancy.

What makes percept™ different to other non-invasive prenatal tests?

Unlike other non-invasive prenatal tests which involve the blood sample being shipped overseas for analysis, percept™ is processed and analysed in VCGS’ laboratories in Melbourne. This means you will get your test results quickly (within 3-5 working days) because your blood sample is kept in Australia.

VCGS provides a comprehensive service for patients who chose to have non invasive prenatal testing. Pre and post-test counselling is available to all women undergoing the percept™ test through VCGS’ team of genetic counsellors. All profits from percept™ are put back into research performed by Murdoch Children's.

How do I arrange the test?

  1. Discuss percept™ with your genetic counsellor or doctor.
  2. A test request will then be completed by your genetic counsellor or doctor.
  3. You will then need to have your blood taken. Because percept™ is a highly specialised test, only certain bleeding centres are available for collection. Please see the VCGS website for percept™ collection sites.
  4. Most results will be available from your genetic counsellor or doctor within three to five working days of sample receipt. VCGS will also send a copy of the test results to other healthcare professionals indicated on the request form.

When can the test be performed?

There are two options for timing of the test:

Option 1: You can choose percept™ as your first screening test from 10 weeks gestation. Prior to NIPT you need to have an ultrasound to determine an accurate due date and determine whether you are carrying a single baby or twins. When choosing NIPT as your first screening test, VCGS recommends that you also consider having a 12 week ultrasound to check the structural development of your baby. You may also have combined first trimester screening (cFTS), which involves a blood test and ultrasound, at the same time as NIPT.

Option 2: Alternatively, you may choose to have percept after combined first trimester screening (cFTS). If you are not reassured by the results of your cFTS, further screening with percept™ may help with your decision making. Sometimes, following a high risk cFTS result, a diagnostic test (CVS or amniocentesis) may be a more appropriate option (see below).

When should I consider invasive testing?

percept™ only detects a limited range of chromosome conditions. In some situations, an invasive diagnostic test such as a chorionic villus sampling (CVS) or amniocentesis may be more appropriate. These tests will give more detailed and accurate information about your pregnancy. Your doctor or genetic counsellor will discuss these methods with you if invasive testing is recommended.

These situations include:

  • If your ultrasound finds a structural abnormality
  • If a combined first trimester screening risk is very high (>1 in 50)
  • If the nuchal translucency is very large at the 12 week scan (≥ 3.5mm)

It is important to note that NIPT is an advanced screening test but is NOT a replacement for CVS or amniocentesis.

Concerned woman looking at laptop screen

What do the results mean?

percept™ will report the following results:

Low risk: Most results are reported as low risk. This means it is very unlikely the pregnancy is affected by the specific conditions screened for. However, other conditions or abnormalities may still be present. We recommend all patients have an 18-20 week ultrasound.

High risk: A high risk or intermediate (borderline) risk result means that the pregnancy is at increased risk for the chromosome condition reported. The only way to know for sure if your pregnancy is affected, is to have a diagnostic CVS or amniocentesis. These diagnostic tests will identify those women whose result may have been a ‘false positive’ – meaning their high risk screening result was incorrect and their pregnancy is actually not affected.

No result: In some cases, no result is obtained. This is very uncommon (<1% of samples). If this occurs the laboratory will request a repeat specimen for testing at no additional charge.

What support is offered?

You can contact your doctor for information about your test results or you may also contact a VCGS genetic counsellor (03 8341 6201) to discuss any questions you may have about your test results.

VCGS genetic counsellors offer support to women who undergo percept™ non-invasive testing, and are on hand to answers questions and discuss options. Our genetic counsellors work as part of a team so they can liaise with clinical laboratory scientists, doctors, support organisations and hospital and community services on your behalf.

Where can I found out more about percept™?

To find out more about how percept™ works, visit the VCGS website.

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