Nuchal scan for Down's syndrome |
Could
my baby be born with Down's syndrome?
Your
baby's chances of having a chromosomal abnormality, like Down's
syndrome, are determined by the baby's nuchal fold measurement,
your age, and hormone levels (PAPP-A HIG). Your age is factored in
because although anyone can have a baby with a chromosomal
abnormality, the risk increases as you age.
Nuchal
translucency screening helps assess your baby's risk of having
chromosomal abnormalities, as well as major congenital heart
problems. The two parts of the screening process are a nuchal
translucency ultrasound and a blood test when you are between 11
weeks and 2 days to 14 weeks pregnant. The nuchal scan allows us to
measure the clear (translucent) space in the tissue at the back of
your developing baby's neck.
It
is a noninvasive diagnostic test that uses sound waves to create a
visual image of your baby, placenta, and uterus. Babies with
abnormalities tend to accumulate more fluid at the back of their neck
during this stage of pregnancy, causing this clear space to be larger
than average. The blood test measures the risk associated with your
age, and increases the detection rate.
Parents
may decide that it does not matter to them to have a child with a
disability and can therefore opt out of screening. Before the screen,
we advise parents to discuss what they may decide to do if their
screen indicates an unacceptable level of risk. The nuchal scan is
not 100% accurate and couples need to consent
that they understand this.
Like
other screening tests, a nuchal scan won't give you a diagnosis, but
it can assess your baby's risk for certain problems. If the risk is
low, the results will offer you some reassurance. If the risk is
high, you will have the opportunity to consider amniocentesis or
chorionic
villius sampling
(CVS) to find out whether your baby is actually affected. These tests
are more invasive but establish the risk with greater accuracy.
Consult
your gynaecologist/midwife:
- to
refer you for a nuchal scan
- for
a second opinion, if a concern arose after a nuchal scan
- to
help you decide whether you require additional tests to assess baby
- to
help you decide what to do, in the unlikely event of there being a
problem with baby
Because
the nuchal scan requires special training and equipment, it is not
available everywhere. At Beth's Doctors, our private consultant
gynaecologists and obstetricians are specialists in fetal maternal
medicine. Their experience includes working in a tertiary referral
centre (where doctors refer at-risk pregnancies or where pregnant
couples can go for a second opinion.) We offer the nuchal scan as
part of a comprehensive package of maternity care available to
private patients or to couples who need help on a one-off basis.
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