Amniotic fluid test is a fetal diagnostic examination.
An amniotic fluid test can ascertain with great
certainty whether the fetus has chromosome disorders,
such as Down syndrome (formerly called Mongolism), or
more severe forms of spinal hernia.
At special issues,
it is sometimes also possible to detect a fairly large
number of very rare hereditary diseases. Amniotic fluid
tests are performed when there is an increased risk of
these diseases in the fetus. A normal amniotic fluid
test does not guarantee that the fetus is healthy from
other points of view.
What is fetal diagnosis?
Fetal diagnosis in a broad sense means all the
various checks performed throughout pregnancy at the
Midwife Reception (MVC). Checks are performed to ensure
fetal health. However, what are commonly called fetal
diagnostics are more specific studies such as:
- Ultrasound at 15-20 weeks of pregnancy.
- Directed ultrasound.
- Benchmarking methods for assessing probability
of Down syndrome:
Late blood test.
Ultrasound 15-20 weeks.
- Chorionic villus sampling.
For which women can amniotic fluid test be relevant?
An amniotic fluid test can be offered to women under
the following conditions:
- Women who were 35 or older when they became
- Parents who have previously had children with
Down syndrome or other chromosome disorder.
- Parents who in previous investigations have
shown themselves to have a chromosome change.
- In some cases, abnormalities in the fetus that
can be suspected to be caused by chromosome
disruption have been detected in a standard
- When the woman is considered to be at risk,
taking into account established risk assessment
- Parents who have previously had a child with
spinal cord hernia or similar brain malformations or
themselves have or have had spinal cord hernia.
- Parents who have previously had children with
hereditary metabolism disorder.
- Parents with genital hereditary illness, such as
hemorrhagic disease, in the genus.
- The woman requests it because she is worried
that the child may have a chromosome abnormality.
- Amniotic fluid tests are sometimes required to
examine and treat other conditions during pregnancy,
such as Rh immunization. In these cases, the
amniotic fluid is analyzed to detect substances in
the fluid itself, and not just to look at the
Information about the amniotic fluid test is provided
by the doctor and / or midwife where the pregnancy is
controlled. However, the final decision whether or not
to undergo sampling is the woman's own, if she belongs
to any of the above groups.
What analyzes are performed?
In the vast majority of patients, two types of
amniotic fluid are performed: chromosome examination to
exclude chromosome disorder and AFP examination to
exclude spinal cord hernia.
When is the test taken?
The sample is taken approximately during pregnancy
week 15, as there is so much amniotic fluid that some
can be sucked out for examination.
How is amniocentesis done?
Prior to sampling, a thorough ultrasound examination
is performed to find the best sampling site and avoid
the fetus and placenta. The doctor then, under
ultrasound control, inserted a thin needle through the
abdominal wall and the uterine wall into the fetal sac
and sucked out about 15 ml of amniotic fluid. The
procedure is done without any form of stunning. The
mother may feel a slight discomfort, but by and large,
the sampling is virtually painless. The fetus is unaware
of the procedure.
The prospective mother does not have to be housed,
but can go home the same day. Heavy lifting should be
avoided in the next few days after sampling. The
amniotic fluid sample is sent for chromosome analysis to
the nearest clinical genetics laboratory.
Women with Rh negative blood group (one in eight
women have this) receive a gamma globulin (anti-D)
syringe to prevent antibody development. Anti-D is also
given to some mothers after childbirth, depending on the
Rh factor the newborn has. The use of anti-D is a great
Are there any risks with the procedure?
The risks are considered to be very small if the
procedure is performed in connection with an ultrasound
examination. However, miscarriages have been seen within
the next few weeks, which may have had to do with
sampling. The general incidence of miscarriage is
usually about 1-2 percent in pregnancy week 13-15. For
women who have undergone amniocentesis, this is stated
to be about 0.5 percent higher, partly because these
women themselves constitute a risk group.
How long does it take to know the result?
Answers to all age-dependent chromosome
abnormalities, ie Down syndrome, trisomy 18 and 13 can
generally be provided within a week. When measuring AFP,
it takes about a week for response. The answer is sent
by letter from the doctor who performed the amniotic
fluid test. Answers to complete chromosome analysis
usually take 3-4 weeks. If the test is normal, you will
receive an answer directly from the laboratory.
How reliable is the result of an amniotic fluid
There are very few things in life that can be
guaranteed to 100 percent. Also, fetal diagnostics
(amniotic fluid testing and ultrasound examination)
provide no hundred percent guarantee that the expectant
child is healthy in all respects.
What if the test shows something abnormal?
Should the chromosome examination or AFP examination
show anything abnormal, the doctor who performed the
sampling will receive a response and contact the parents
directly for discussion. Some chromosome abnormalities
can cause very serious damage, while others can be
completely harmless. Sometimes, if more unusual or
complicated diseases are found, consultations with the
genetic laboratory may be necessary.
If the AFP value is high, it may indicate spinal cord
hernia or other similar disease in the fetus. In the
first instance, a new ultrasound examination is done
with special focus on the fetal spine, brain and
abdominal wall. Should this ultrasound examination be
found to have serious damage to the fetus, or if the
chromosome examination shows abnormalities, it may be
necessary to interrupt pregnancy. It is a decision,
however, that can only be made after careful discussion
and advice. It is therefore important that the parents
decide beforehand on how to do if the test should show