8 June, 2006
Down Syndrome Antenatal Screening Under Review
A large number of health professionals are being advised of concerns relating to the current practice of antenatal
screening for Down syndrome.
Manager of the National Screening Unit, Karen Mitchell, says letters have been sent to health professionals highlighting
current concerns, which include referrals for diagnostic procedures (amniocentesis and chorionic villus sampling) and of
steps they can take to improve current practice and ensure that women are better informed.
The National Screening Unit commissioned Professor Peter Stone from the University of Auckland to assess current
practice
of antenatal screening for Down syndrome in New Zealand. Professor Stone's Report states that current practice is
“increasingly expensive and labour intensive”. It also suggests that "more normal pregnancies may be adversely affected
by amniocentesis than the numbers of Down syndrome fetuses detected.” Amongst other things, the report recommends that
current practice be urgently reviewed.
The National Screening Unit is to review current practice and with the help of an External Advisory Group will provide
initial advice to Minister of Health, Pete Hodgson, early next year.
Karen Mitchell says, "amniocentesis and chorionic villus sampling, carry a 0.5% to 1% chance of miscarriage and should
only be carried out where a woman is informed of the risks associated with the procedure and has given informed consent
to the procedure."
"Ensuring that pregnant mothers have a safe pregnancy is our main goal. There are immediate steps that can be taken now
to limit the risks associated with testing, and to ensure that women are better informed", says Karen Mitchell.
The letter states that women should not be referred for amniocentesis or chorionic villus sampling based on maternal age
alone. All women consulting a health practitioner in the first trimester of pregnancy can be offered a Nuchal
Translucency ultrasound scan, which is publicly funded. Women should also be informed about the difference between a
screening test and a diagnostic test, and the risks associated with the different types of screening tests and
diagnostic tests.
Women should also be informed as to whether the radiographer is accredited to perform a Nuchal Translucency ultrasound
scan, which should be performed between 11 and 13 weeks and 6 days of pregnancy. These scans should only be performed by
practitioners who have current accreditation.
Questions and Answers
1. What are the concerns with amniocentesis and chorionic villus sampling (CVS)?
Amniocentesis and chorionic villus sampling procedures carries a small risk of miscarriage (0.5 -1 percent). Concerns
have been raised that these tests are being provided to women who may not have an increased chance of having a child
with Down syndrome and who have not been informed about the risk of pregnancy loss associate with the tests. The use of
these invasive diagnostic tests should be limited to women who have an increased chance of having a child with Down
syndrome and who have made an informed choice to use those tests.
2 How will the Ministry limit the use of invasive diagnostic tests?
The Ministry has written to all midwives, general practitioners, obstetricians, laboratories, radiologists and
radiographers to advise them of ways that current practice can be improved now. The use of invasive diagnostic tests can
be reduced by offering each pregnant woman a screening test that assess her individual chance of having a child with
Down syndrome. Each woman should also be informed of the risks associated with the screening tests and the diagnostic
tests. This will allow women to make informed decisions about the use of amniocentesis and chorionic villus sampling.
3. What antenatal Down syndrome screening is currently available?
Currently all women consulting a health practitioner in their first trimester of pregnancy can be offered a Nuchal
Translucency ultrasound scan, which is publicly funded. Women who do not consult a health practitioner in their first
trimester of pregnancy can have a second trimester maternal serum screening test. This test is not publicly funded at
present; it costs approximately $75 and is available from LabPlus (Auckland DHB).
4. Who will make up the external advisory group?
Members appointed include consumers with expertise in women’s health and maternity services, representatives of the
disability sector, and others with experience in:
- ethics
-midwifery
- general practice
- obstetrics
-paediatrics
- cytogenetics
-clinical genetics.
The Advisory Group will have its first meeting in June 2006. The Chair of the Group is still to be decided.
5. Does the Ministry aim to reduce the number of babies born with Down syndrome every year?
No, this is not about reducing the numbers of babies born with Down syndrome. This is about ensuring that screening
services offered to women during pregnancy do not cause unnecessary harm to women and their pregnancies.
ENDS