Women’s Diagnostic Centre
Patient Information
Nuchal Translucency Assessment
What is Nuchal Translucency?
Additional risk assessment available?
All developing babies have a layer of fluid on the back of their
bodies between the skin and the underlying soft tissue. This layer is
translucent on ultrasound and its thickness is measured at the level of
the neck. This is called the Nuchal Translucency Measurement.
The Nuchal Translucency Assessment can now be performed in
combination with a blood test. This blood test is called Free Beta
HCG and PAPP-A quantification. The Ultrasound alone detects
approximately 80% of abnormalities. With the addition of the blood
test this can be increased to 85%. The blood test is best performed
at approximately 10 weeks and should be performed at least three
working days prior to the Nuchal Translucency Assessment.
The optimum time for performing this assessment is between 11
weeks and 4 days and 13 weeks 6 days of pregnancy. Pregnancies
showing an increased thickness of the Nuchal Translucency Fold has
been associated with an increased risk of Chromosomal abnormalities,
as shown in research of greater than 100,000 pregnancies scanned
during this gestational period.
All women have a risk of delivering a baby with a chromosomal
abnormality and this risk is increased with maternal age. Down
Syndrome (Trisomy 21) is the most common of the chromosomal
defects and has always been difficult to detect before birth.
What is the Nuchal Translucency Assessment?
The Nuchal Translucency Assessment is offered to pregnant
women to assess major chromosomal congenital abnormalities.
The test suggests which pregnancies are at a higher risk of
abnormality and may need further investigation. A normal result does
not guarantee a normal baby but does imply that an abnormality is
unlikely. An abnormal result does not mean the baby is abnormal but
suggests the baby should be further investigated.
Should I have this test performed?
This is a question each parent must answer for themselves.
The main reason for performing screening tests such as this is to
detect abnormalities. This allows consideration of further invasive
testing or possible termination of pregnancy if an abnormality
is found.
Patients most likely to benefit from this test are older women who
are pregnant (as older women have a higher risk of chromosomal
abnormalities), women who have had an abnormal pregnancy
previously and women with a family history of abnormal pregnancies.
Who will perform the scan?
An accredited Sonographer (a technologist specially trained in
ultrasound) or Radiologist (a doctor who specialises in medical
imaging) will perform the scan.
This test is a measurement performed during an ultrasound. It is
painless and carries no risk to the pregnancy. In a large majority of
patients the ultrasound is performed with the probe on the abdomen
but in a small percentage a scan performed through the vagina may
be required.
After combining Nuchal Translucency Measurement with your
age (and blood tests if available) and utilising a specially designed
computer program, we can calculate your risk of having a baby
with a chromosomal abnormality for this pregnancy. This risk will be
expressed as “1 in...”. A low risk is expressed as 1 in more than 300.
A high risk is expressed as 1 in less than 300.
What else can this scan assess?
When will I get the results?
At this early ultrasound we can:–
confirm that you are pregnant and determine the age of
the fetus,
The results will be available shortly after the examination is complete.
You can either wait for your results or alternative arrangements can be
made to collect them at a later stage.
–
diagnose multiple pregnancies, and
What if I am shown to be at high risk?
–
examine the baby for some major defects.
If the Nuchal Translucency Assessment determines your baby is at
an increased risk of a chromosomal abnormality, you should discuss
this result with your referring doctor. This does not mean the baby is
abnormal but indicates further tests may be needed.
A further ultrasound at 18 to 20 weeks is recommended as this is the
best time to detect the majority of structural defects.
Most high risk pregnancies will be normal. Your doctor will be able to
provide advice about further testing, such as Chorionic Villus Sampling
(CVS) or Amniocentesis, to assess chromosomal abnormalities.
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Women’s Diagnostic Centre
Is there a Medicare Rebate?
Follow up
Please discuss your eligibility for a Medicare rebate with your
referring doctor prior to making an appointment. You will be
eligible for a Medicare rebate if there are medical indications which
warrant the scan at this stage of the pregnancy, for example fetal
anomaly, uncertain dates or viability. These indications must be clearly
stated on the request form. If there are no indications for the scan,
other than for Nuchal Translucency, you will not be eligible for a
Medicare rebate.
As an accredited member of the International Research Programme
for Nuchal Translucency Screening, followup of the outcome of your
pregnancy is important. Therefore, we may contact you either by mail
or phone for follow-up after you have delivered your baby. Please
indicate to us at the time of your examination if you do not wish to
be contacted.
Making your appointment
Because of the small time frame in which an accurate measurement
can be taken (after 11 weeks but before 14 weeks) it is essential that
you make an appointment as soon as your referring doctor requests
the assessment be performed. If you are to have the blood tests,
they should be performed even earlier. However, no earlier than
10 weeks if possible. Your doctor should ask for a copy of the results
to be sent to the radiology practice where you are having your Nuchal
Translucency Assessment.
Unfortunately not all babies with Down Syndrome are diagnosed from
this study. Approximately 15-20% of babies with Down Syndrome may
not be detected on this study.
If you have any questions regarding the Nuchal Translucency
Assessment, please do not hesitate to contact one of the following
practices or visit our website.
Administration
PO Box 109 Sunnybank
Queensland 4109
Telephone: (07) 3422 8800
Facsimile: (07) 3343 7055
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