Amniocentesis is the procedure for tapping amniotic fluid . The fluid drawn can be used for diagnosing many newborn defects and chromosomal disorders. This section is the brief explanation of indications, uses and procedural guidelines for amniocentesis. For more details visit website of innoclazz academy
2. Introduction
As the pregnancy related diseases are influencing the health
of newborn, new methodologies are being developed to
detect the underlying causes. One such technique is the
amniocentesis, which is a predominant technique under
prenatal diagnostic measures. It is a medical procedure
carried out to detect the fetal infections, chromosomal and
genetic defects as well as to find out the gender of the
baby. However, unless it is strongly indicated for a medical
reason, sex determination is prohibited in India. During
amniocentesis, a small amount of amniotic fluid is being
extracted by making a tiny puncture into the amniotic
sac. This is because, the amniotic fluid lie close to the
fetus contain fetal cells which can give a clue about any
defect in their chromosomes and DNA.
3. Indications to perform amniocentesis
The procedure is usually performed between
14-20 weeks nevertheless, it may be necessary
to perform the procedure on emergency basis
as indicated by the physician.
It is used for both diagnostic and treatment
purposes.
4. Indications cont……….
During the third trimester, it is used to determine
labor-related issues.
At the time of premature rupture of membranes, the
sample can help to detect the evidence of uterine
infections.
It is also helpful to find out the severity of fetal
anemia in babies with Rh disease so that prior
preparation can be done to arrange for lifesaving
blood transfusions.
Another reason for amniocentesis is to assess the lung
maturity which can be done shortly before delivery.
Continue…………………………
5. Indications cont.…………..
It is a frontline tool to detect diseases such as Down
syndrome (Trisomy 21), trisomy 13 , trisomy 18, sex
chromosome anomalies, Fragile X syndrome, inherited
metabolic disorders, neural tube defects such as
anencephaly and spina bifida ( with the help of alpha-
fetoprotein levels).
Amniocentesis can collect DNA from the fetus that can
then be compared to DNA from the potential father.
As a therapeutic measure it is used to decompress the
polyhydramnios to drain out the excess of fluid that
hinders the delivery which eventually help to prevent
aspiration of fluid by the baby.
6. Indications cont.…………..
On the genetic front, if a mother had a
chromosomal condition or a neural tube defect
in a previous pregnancy, it is advisable to go
for amniocentesis.
If the babies born to women aged above 35
years, the risk of chromosomal conditions is
high and in such case, a health care provider
might suggest amniocentesis.
Women with family history of a specific
genetic condition may need to recheck her
status by amniocentesis.
7. Risks of amniocentesis
Improper procedure can leak the amniotic fluid
which can lead to a state of complete collapse
which is dangerous.
In some cases, repeated amniocentesis can lead to
miscarriage.
Fetal injury by the needle used for amniocentesis is
possible however, serious needle injuries are rare.
Sometimes amniocentesis may allow the baby's blood
cells to enter the mother's bloodstream causing Rh
reaction. Mother`s Rh antibodies that cross the
placenta can damage baby's red blood cells.
8. Risks cont………
Improper techniques can cause uterine and
neonatal infection.
If a mother is already suffered from infectious
diseases such as hepatitis C, toxoplasmosis or
HIV/AIDS — the infection might be transferred
to the baby through this procedure.
9. Preparation for amniocentesis
Mother must be advised to drink plenty of
fluids before the procedure but the bladder
should be empty during amniocentesis to
minimize the chance of puncture
The procedure must be explained to the
mother to reassure and gain support.
A legal consent form should be filled before
the procedure begins.
Trace out the history of uterine and urinary
tract infections to be on safer side. It is not
advisable to undergo amniocentesis if the
mother is suffering from a known infection.
10. Procedure for Insertion of amniocentesis needle
A sterile amniocentesis needle is being
inserted with the help of ultrasound into the
wall of the uterus through mother's abdominal
wall.
The needle must be slowly advanced till it
reaches amniotic sac.
Puncturing must be done slowly because
improper insertion can cause rupture of the
sac.
11. Cont………….
Approximately 20ml of amniotic fluid is drawn
into the syringe connected to other end of the
needle.
This procedure can be performed with a single
needle or a double needle technique based on
individualized patient factors and physician
preference.
Out 20 ml of amniotic fluid, the first 2 ml has
to be discarded because it is a mixture of
blood and amniotic fluid.
12. Cont…………….
If the amniocentesis is used for prenatal
genetic diagnosis, fetal cells must be
separated first the whole amniotic fluid and
these must be preserved in a laboratory
setting and then stained to observe under a
microscope.
After the procedure, the mother must be
instructed to take rest for at least 24 hours
post-procedure.
Any untoward reaction such as bleeding,
abdominal pain, fever and fluctuation of blood
pressure must be reported immediately.