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Non-invasive prenatal diagnosis using cell-free fetal DNA: implications for parents

15 September 2008

By Jane Fisher

Director, ARC (www.arc-uk.org)

Appeared in BioNews 475
Antenatal Results and Choices (ARC) is the only UK charity providing non-directive information and support to parents before, during and after antenatal testing and when an abnormality is diagnosed in an unborn baby. We have 20 years' experience of talking to parents on our National Helpline on all aspects of antenatal testing and its aftermath. Over two decades our most common call is consistently from parents wrestling with the decision about whether to have an invasive test such as CVS (chorionic villus sampling) or amniocentesis. Because both procedures carry a one per cent risk of miscarriage, parents agonise over whether to put their pregnancy at risk in order to have conclusive information on a genetic condition.

ARC's specialised helpline team helps parents work out how to proceed in a way that is right for them in their individual circumstances. We have no agenda other than to enable them to make the decision they can best live with. It can be a very distressing process for parents as they weigh up the importance to them of having a confirmed diagnosis (or gaining reassurance) against the small but significant chance of losing a wanted pregnancy as a result of the procedure. Many are desperate to know if there is a risk-free alternative. From our experience we can predict that if cffDNA (cell-free fetal DNA) testing were to provide risk-free but reliable diagnoses of aneuploidies and other genetic conditions it would prove extremely popular with many parents.

For most parents the earlier reassurance that cffDNA testing would bring will be welcome. However, we must avoid making assumptions that an earlier diagnosis will necessarily be easier for parents to cope with. Making painful decisions about the future of what is most often a wanted pregnancy is difficult at any gestation. Furthermore, there is no evidence that earlier terminations for fetal abnormality have substantially less emotional impact on women and couples than those carried out later in the pregnancy.

Another concern from the parental perspective is the form cffDNA testing takes, being a simple blood test. Women are very accustomed to having blood taken in pregnancy and while holding out an arm for a needle to be inserted is not always pleasant, it is something with which every pregnant woman is familiar. The 'routine' nature of the procedure could mean that some women embark on it without considering the possible implications and so are particularly distressed if test results bring unexpected news about the pregnancy. This has implications for how pre-test counselling and consent issues are handled.

In fact there is a precedent for a non-invasive diagnostic tool in routine use in antenatal care, namely ultrasound scanning. Every time an ultrasound probe is placed on the abdomen of a pregnant woman there is the possibility that an abnormality will be detected. Although information provision to women about the purpose of antenatal ultrasound is improving, we cannot underestimate the profound impact on parents when the scan shows that there is something wrong. However well-informed a woman may be, such news will always come as a shock and generate considerable anxiety and distress. This will also be the case for a diagnosis made from cffDNA testing, even if it comes earlier in pregnancy. Just as we do now in the context of ultrasound, ARC would advocate the implementation of carefully co-ordinated care pathways in the instance of the diagnosis of an affected pregnancy.

As mentioned previously, we at ARC can confidently forecast that most parents will welcome the introduction of early non-invasive prenatal genetic testing. Indeed many are impatient for its arrival in practice and we must be careful not to raise unrealistic expectations around how soon it might be available within the NHS. This impatience will lead some parents to the Internet to access private provision. It will therefore be important to both help parents to assess the quality of such services and to consider the possible consequences of this route.

From ARC's perspective, potential advances in cffDNA testing will be of significant benefit to parents and families. We would want to see it implemented into practice in a considered way, with the excitement of such an advance not blinding us to its consequences. High quality pre-test information is of course crucial, but we would also strongly advocate an emphasis on ensuring that individualised care and support pathways are in place for the parents for whom the test results bring difficult news about their pregnancy.

 

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