2. • A procedure performed usually in the beginning of pregnancy to
detect chromosomal abnormalities in the fetus.
• Usually done when a woman is between 16 and 22 weeks pregnant.
•During this procedure a sample of amniotic
fluid is taken from the amniotic sac (amnion)
surrounding the unborn baby and its DNA is
examined for genetic abnormalities.
• The amniotic fluid - has cells that the skin
of the developing baby has shed, as well as his/her waste products.
Each cell from the baby in the fluid contains their complete set of DNA
(genetic information). Analyzing these cells helps the doctors assess
the fetus' health and detect any potential problems.
• The entire amniocentesis appointment lasts approximately 45
minutes- most of which involves a detailed ultrasound examination.
3. Who is a candidate for amniocentesis?
•Any pregnant woman who, at her due date, will be 40 years of
age or older.
•Any woman whose Combitest® results are high risk (blood tests
and/or fetal ultrasound).
•Any woman whose ultrasound results indicate a potential fetal
chromosomal anomaly.
•Any woman who has a family history or whose partner has a
family history of one or more incidents of chromosomal
anomalies or genetic disorders with a high recurrence risk.
•It is also possible for women under the age of 40, with no
history of genetic disorder to have an amniocentesis; it is a
matter of personal choice.
4. What can be detected through an
Amniocentesis?
•Nearly all chromosome disorders, including Down’s Syndrome
as well as sex chromosome abnormalities (such as Turner
syndrome and Klinefelter syndrome).
•Several hundred genetic disorders, such as cystic fibrosis and
sickle cell disease. The test is not used to look for all of them,
but if your baby is at increased risk for one or more of these
disorders, in most cases amniocentesis can usually tell you
whether he has the disease
•Neural tube defects such as spina bifida.
• Amniocentesis is the only way to obtain information about
fetal lung maturity.
5. •In order to understand amniocentesis it is important to know
about certain parts of the body and how they work..
AMNIOTIC SAC
AMNIOTIC FLUID
UMBLICAL CORD
PLACENTA
6.
7. • Adviced to rest for 24 hours
• No strenous work, exercise for 72 hours
• No air travel for 72 hours
• Seek urgent medical attention if –
feeling shivery.
High fever of 38 degree celcius or above.
• Persistant lower back pain and abdominal pain.
• After the amniocentesis procedure, the sample of amniotic fluid (the
fluid that surrounds the unborn baby in the womb) will be taken to a
laboratory for testing.
• There are two different types of tests:
• a rapid test
• a full karyotype
8. • A rapid test looks for abnormalities on specific chromosomes (the
parts of the body’s cells that carry genes). A rapid test can identify a
number of chromosomal conditions that cause physical and mental
abnormalities. These are:
• Down's syndrome – caused by an extra chromosome 21
• Edward's syndrome – caused by an extra chromosome 18
• Patau’s syndrome – caused by an extra chromosome 13
• The results of a rapid test should be ready after three working days.
This test is almost 100% accurate, but it only tests for the three
conditions listed above.
9. • Each cell in the body contains 23 pairs of chromosomes. A full
karyotype checks all of these.
• The cells in the sample of amniotic fluid are grown for up to 10 days
in a laboratory before being examined under a microscope to check
for:
• the number of chromosomes
• the appearance of the chromosomes
• Results from a full karyotype will usually be ready in two or three
weeks. In about 1 in every 100 tests, the results may not be clear.
This could be due to the mother’s blood contaminating the sample of
amniotic fluid, which may have prevented the cells from growing
properly.
10. •After amniocentesis, the sample of amniotic fluid is sent to a
lab for analysis.
•Results usually take 10 days to 3 weeks, depending on the lab.
•It takes that long to get results because the cells have to grow
in the lab in order to analyze them.
•In the lab, genetic and chemical tests are done.
•For genetic tests, certain chromosomes and genes are
analyzed.
•For chemical tests, proteins, minerals and other compounds in
the amniotic fluid are analyzed.
•Amniocentesis results will either be positive or negative.
11. Negative test results
If the test result is ‘positive’ it
means the baby has the disorder
that was being tested for. One
should be aware that there is no
cure for the majority of
chromosomal conditions, so she
needs to consider her options
carefully.
Options may include:
continuing with her pregnancy
while getting information and
advice about the condition so she is
prepared for caring for her baby.
ending her pregnancy
Options for ending her pregnancy
will depend on how many weeks
pregnant she is when making the
decision.
• For most women who have
amniocentesis, results of the
procedure will be ‘negative’. That is,
their baby will not have any disorders
that were tested for.
• It is possible to have a negative result
from amniocentesis but the baby may
still be born with the condition tested
for or another chromosomal
condition. This is because a normal
test result does not exclude every
chromosomal disorder.
Positive test results
12. • It is important to be aware of the possible complications during or after
amniocentesis. These are outlined below.
• There is a small risk that amniocentesis can cause a
miscarriage (the loss of the pregnancy). The risk is
estimated to be around 1 in 100.
Miscarriage
• Amniocentesis may cause club foot in your baby. This
is when the baby is born with a deformed ankle and
foot. However, the likelihood of this happening is
higher if you have amniocentesis before week 15 of
your pregnancy.
Club Foot
• Rhesus disease is a condition where proteins in a
pregnant woman’s blood attack her baby's blood cells.
• Rhesus disease is only possible if the mother’s blood is
rhesus-negative and the baby's blood is rhesus-
positive. If this is the case, amniocentesis could
trigger rhesus disease if the mother’s blood is exposed
to the baby’s blood during the procedure.
Rhesus
disease
13. • During amniocentesis, the placenta (the organ that
links a pregnant woman's blood supply to her unborn
baby's) may be punctured by the needle. Sometimes
this is necessary to access the amniotic fluid. If this
happens, the puncture wound usually heals without
any more problems developing.
• Ultrasound (where high frequency sound waves are
used to create images) is now commonly used to
guide the needle. This significantly reduces the risk
of injury.
Injury
from
needle
• In very rare cases, an infection may develop if the
procedure introduces bacteria in the amniotic sac
(the sac surrounding the fetus that contains amniotic
fluid). This can cause:
• a high temperature (fever) of 38ºC (100.4ºF) or above
• tenderness of abdomen (tummy)
• contractions (when your abdomen tightens then
relaxes)
• One should seek medical attention if she has any of
these symptoms. The risk of developing a serious
infection from amniocentesis is estimated to be less
than 1 in 1,000.
Infection
14. • Amniocentesis is a safe procedure that can provide helpful
information about the health of a fetus. It may be offered
to woman who are at a higher risk of having a baby with a
genetic disease. The risk of miscarriage of amniocentesis is
about 0.5%, or 1 in 200.
• It is the patients decision whether the benefits of the
procedure outweigh the risks.
