Antenatal DNA blood tests: patient communication implications

With cell-free DNA blood tests readily available in the early stages of pregnancy, we look at the communication challenges these tests can raise for you.

Medicare rebates have been available for genetic carrier screening since November 2023. However, cell-free DNA testing in pregnancy is not covered by Medicare or private health insurance.

Non-invasive prenatal testing (NIPT) 

Non-invasive prenatal testing (NIPT) is based on the polymerase chain reaction (PCR) probing of cell-free foetal DNA extracted from a maternal blood sample, and has been shown to have a high specificity and sensitivity. However, it is not always reliable, and similar to chorionic villus sampling (CVS), mosaicism of placental tissue may be identified as representing the foetus. Therefore, NIPT can be positive in the presence of a normal foetus. Further diagnostic testing should be recommended to patients who have a positive NIPT.

Additionally, NIPT is not always possible, as the percentage of cell-free foetal DNA may be low in some women, such as those with a high body mass index (BMI). 

Testing for aneuploidy involving chromosomes 21(Down syndrome), 18 (Edwards syndrome) and possibly 13 (Patau syndrome), using the identification of cell-free foetal DNA in maternal blood during the first trimester of pregnancy, brings a new dimension to the identification of triploidy in those at low as well as high-risk of these abnormalities.

NIPT can also identify foetal sex. The ability to identify a Y chromosome may become useful in managing carriers of X-linked disease and detecting genetic disease, but also has implications relating to sex selection.

NIPT can extend to other aneuploidies and gene mutations, including sex chromosome and genome wide testing.

The communication challenge

For most obstetricians and general practitioners, the challenge with all antenatal testing has been to explain to patients, in easily understandable terms, the difference between a screening test to detect early risk factors and a diagnostic test to establish the presence of a disease or condition. 

The concept of risk as it applies to an individual, also varies significantly from patient to patient. These factors have led to civil claims and complaints to medical regulatory authorities.

Avant is seeing cases where members have received patient complaints alleging they either failed to offer the full range of tests, or adequately explain the limitations of tests. 

Provide information and keep records

It’s important to stay up to date with ongoing developments in this area, and to provide individual patients with pertinent information – both verbally and something they can read later. Obstetricians and general practitioners could reduce the likelihood of a claim or complaint by explaining to patients what tests are likely to be relevant to their particular situation.

As with any procedure or test where the patient will incur costs, there needs to be informed financial consent. This should include the approximate potential cost and the lack of a Medicare rebate.

Any discussion regarding cell-free DNA tests should be recorded in the medical record. All verbal advice should be augmented by written information, such as the fact sheet available from RANZCOG or content provided by the lab handling the test. A record should be made of the written information provided, including the version number if relevant. Any patient concerns should also be discussed and documented. At the next visit it is worth checking whether the patient has read the information and whether they have any questions. This discussion should be documented in the records. 

The rapid rise in knowledge associated with the sequencing of the human genome, and the translation of this into clinical practice, is likely to place an ongoing focus on the assessment and advice provided by obstetricians and general practitioners.

Key points

• Claims and complaints may arise if you do not discuss the availability and limitations of antenatal testing.
• By continually updating your knowledge of the latest advances in available testing, you will be well-placed to offer the appropriate testing and advice to your patients.
• Document all verbal and written information you provide to patients.

More information

For medico-legal advice, please contact us on nca@avant.org.au or call 1800 128 268, 24/7 in emergencies.

• Case: O&G’s consent discussion found appropriate after patient complains of failure to warn of risk of pregnancy
• RANZCOG patient  fact sheet: Prenatal Screening for Chromosomal and Genetic Conditions
• Australian Family Physician article (October 2017): Non-invasive prenatal testing
• RACGP: Prenatal testing