Early and accurate: new DNA blood tests take pregnancy screening to new levels
New tests are noninvasive, and results are available within 10 days
Prof Fergal Malone, chairman of the RCSI department of obstetrics and gynaecology at the Rotunda Hospital in Dublin.
Advances in pregnancy screening mean a woman can now find out as early as nine or 10 weeks into her pregnancy, with more than 99 per cent certainty, whether the foetus she is carrying has Down syndrome or Edwards syndrome, two genetic disorders.
The new foetal DNA blood tests can separate minute amounts of foetal DNA from maternal DNA and are noninvasive, unlike traditional screening methods, with results available within 10 days.
Prof Fergal Malone, chairman of the RCSI department of obstetrics and gynaecology at the Rotunda Hospital in Dublin, says: “The advent of foetal DNA testing from the mother’s blood is a major advance in screening, which has been available in Ireland for the past 12 months. A blood sample is taken from the mother at nine or 10 weeks and shipped off to a lab in California for testing; 10 days later, you have your results. The standard screening test for Down and Edwards syndrome was the nuchal translucency scan and blood test, which had an 85 per cent detection rate. The new tests are much more accurate and can give huge reassurance to parents with zero risk to the pregnancy.”
Malone will be speaking about the options for screening pregnancies for foetal abnormalities as part of the Royal College of Surgeons in Ireland (RCSI) MiniMed lecture series, tomorrow.
Where a foetal DNA test shows a high risk for Down or Edwards syndrome, the patient must still undergo the normal tests such as amniocentesis – in which a needle is inserted through the mother’s abdomen, through the wall of the uterus and into the amniotic sac, from which a small amount of amniotic fluid is taken – or chorionic villus sampling, which involves taking a sample of placental tissue, to confirm the condition 100 per cent. These tests are much more invasive than DNA blood testing and carry a risk of miscarriage.
“The correct and conventional approach today is that screening tests for these conditions are available to everybody, regardless of age. We know the risk of genetic abnormalities increases as women get older, particularly over the age of 35, but the majority of babies born with Edwards and Down syndromes are born to women under 35, as there are more women under 35 having babies,” Malone says.
He says it is a shame that there has never been a ringfenced budget for screening services in Ireland, unlike within the NHS in the UK. Foetal DNA testing and other forms of screening are available in Ireland only as a voluntary opt-in service, which means patients have to ask for and pay for these tests. He says the insurance companies should cover screening services for pregnancy and the HSE should fund the maternity hospitals to provide access to patients without insurance.
Foetal DNA testing costs €500-€800, depending on the hospital, but it is coming down in cost, and Malone suggests that once it falls to €250, this form of screening will probably become more widespread.
In the unfortunate situation where screening during pregnancy confirms that the foetus has a serious or life-threatening abnormality, patients are counselled about their choices, which are twofold: either to continue with the pregnancy or to terminate. Where a patient decides to continue with the pregnancy, they are provided with all the sub-specialty and support services they will need.
“If the patient chooses to terminate, we provide contact details for one of the major NHS hospitals in the UK with which we have close working relationships. It’s not a case of simply directing the patient to the Yellow Pages. The medical team in the UK let us know the results of any tests or autopsies they carry out and the patient returns to us for support such as bereavement counselling or grief management. These are patients who deeply desired and wanted a baby and it is very traumatic to have to make the decision to terminate.”
Malone stresses that a large number of patients who are given the news that their babies will have Down syndrome or another foetal abnormality decide to continue with the pregnancy.
The legal situation in relation to abortion in Ireland makes little difference to their decision to continue with the pregnancy or terminate, he says.
The RCSI MiniMed open lecture series takes place tomorrow from 7pm to 9pm, at the RCSI, 123 St Stephen’s Green. The talks are free and open to the public, but registration is required at rcsi.ie/minimed.
Follow the conversation on the night on Twitter at #RCSIMiniMed.