Down Syndrome Screening in Pregnancy

Screening for chromosomal abnormalities is useful if you would like reassurance about the likelihood of your baby carrying a genetic problem, however neither of the available screening tests can confirm a potential diagnosis.

Screening is a choice for you and your partner; it is useful to consider what you would do with this information prior to undertaking screening.

Since 2015 there are now two methods to screen for a chromosomal problem (aneuploidy).


Percept: Non Invasive Prenatal screening

Specialist Imaging for Women offers the Percept TM prenatal test by VCGS (Victorian Clinical Genetics Services).

This test is otherwise known as the non-invasive prenatal screen.

The small amounts of fetal DNA present in the mothers blood are carefully examined to see if there is an abnormal chromosome count.

This test screens for Down’s syndrome (trisomy 21), Edwards syndrome (trisomy 18) and Patau syndrome (trisomy 13) and rarer trisomies can now also be detected.

The test also screens for abnormal numbers of the sex chromosomes (X and Y) such as Turner syndrome and Klinefelters syndrome. The sex of the baby is also reported and available should you want this information. Please note; our staff will never offer this information. If you would like to know the sex of your baby please ask us directly when you are given the results of the test.

The detection rate of this test is between 95-99% with a detection rate for Down’s syndrome of above 99%.

This is a simple blood test taken from the mothers arm, best performed from 10 week + 3 days gestation and results are available in 3-5 business days.


Victorian Clinical Genetic Services has further information on the test (click here) or contact our reception staff on 8609 4100.


 Combined first trimester screening (Maternal Serum Screening)

The combined first trimester screening test helps to identify pregnancies that have an increased risk of chromosomal or developmental abnormalities . The test is a combination of a maternal blood test taken at 10 weeks gestation,  fetal measurements such as the nasal bone and nuchal thickness (at the back of baby’s neck) taken during the 12-13 week ultrasound and takes into account the age of the mother (or egg donor if applicable). This is a screening test (it does not provide a definitive diagnosis) which gives results of either high risk or low risk.

This is a simple blood test taken from the mothers arm, best performed from 10- 13 weeks gestation. To avoid delays in obtaining the results of the combined first trimester screening we recommended our patients have the bloods taken at 10 weeks gestation. The results are usually available within a couple of days after the 12-13 week ultrasound.

Victorian Clinical Genetic Services has further information on the Maternal serum screening test (click here) or refer to our information on the 12 week ultrasound.


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