Antenatal Screening and Diagnostic Tests
Around 1% of all babies are born with some kind of abnormality.
Fortunately, most of these are minor, but a small percentage can be
serious. Antenatal screening and diagnostic tests are available in
New Zealand to try and predict and diagnose the possibility of
these chromosomal and structural abnormalities. These tests can
give you the option of termination of the pregnancy if a serious
problem is found or in advance knowledge to help dealing with the
problem before the baby is born.
Often parents are sure that they would not request termination
of the pregnancy regardless of any abnormality found. It is
important to remember that these tests are optional, but
sometimes factors such as age may mean that the tests are more
likely to pick up problems. Your lead maternity carer should
discuss the availability of these tests with you so that you have
the option of an informed decision whether you wish to have them or
not.
The screening tests vary in terms of reliability at picking up the
problem and can also say there is a high risk of the problem
falsely, i.e. when no problem exists. When considering whether to
have the screening tests, it is worth remembering that if they come
back 'high risk' (usually greater than 1 in 300), you will be
offered a more accurate diagnostic test. The diagnostic tests are
much more reliable but involve a small but significant risk of
miscarriage. For many women, the decision to have these tests is a
difficult one: your lead maternity carer should help you with the
information needed to enable you to make this decision.
Down Syndrome
This is a set of mental and physical symptoms that result from
having some extra genetic material (chromosome 21). Even though
people with Down syndrome may have some physical and mental
features in common, symptoms of Down syndrome can range from mild
to life-threateningly severe. Mental and physical development are
slower in people with Down syndrome. The chance of having a baby
with Down syndrome increases as a woman gets older. Down syndrome
cannot be cured, but many people with Down syndrome live productive
lives well into adulthood.
Antenatal screening
tests currently offered in New Zealand include the Nuchal
Traslucency Ultrasound Scan, Maternal Serum Screening and the
Anatomy Ultrasound Scan.
Antenatal Diagnostic
tests currently offered in New Zealand include Amniocentesis
and Chorionic Villus Sampling (CVS).
This section on antenatal screening and diagnostic tests has
been prepared by Dr Anil Sharma, an obstetrician and
gynaecologist in Auckland. www.dranilsharma.co.nz
.
