Amniocentesis is a procedure in which you doctor removes a small
amount of amniotic fluid from your womb. The amount of fluid removed is about
30 cubic centimeters. Amniotic fluid surrounds your unborn baby. This fluid
contains some of your baby’s cells and is used to find out if your baby has any
genetic abnormalities. It’s also used to determine if your baby’s lungs are
mature enough to survive outside the womb.
Your doctor will use a long, thin needle to collect a small
amount of amniotic fluid. This fluid surrounds and protects the baby while they’re
in your womb. A laboratory technician will then test the fluid for certain
genetic disorders, including Down syndrome, spina bifida, and cystic fibrosis.
The test results can help you determine whether to continue with
your pregnancy. The test can also tell you whether or not your baby is mature
enough to be born. It’s also helpful for determining whether you need to
deliver early to prevent complications from your pregnancy.
Do I Need Amniocentesis?
Abnormal prenatal screening test results are one common reason
you might need amniocentesis. Amniocentesis can help your doctor confirm or
deny any indications of abnormalities found during the screening test. If you’ve
already had a child with a birth defect or a serious abnormality of the brain
or spinal cord called a neural tube defect, amniocentesis can check whether
your unborn child also has the condition.
If you’re 35 years or older, your baby is at a higher risk for
chromosomal abnormalities, such as Down syndrome. Amniocentesis can identify
these abnormalities. If you or your partner is a known carrier of a genetic
disorder, such as cystic fibrosis, amniocentesis can detect whether your unborn
child has this disorder.
Complications during pregnancy will sometimes require you to
deliver your baby earlier than the full term. Maturity amniocentesis can help
determine if your baby’s lungs are mature enough to allow your child to survive
outside of the womb.
You may also need an amniocentesis if your doctor suspects that
your unborn child has an infection or anemia. Your doctor may also order
amniocentesis if they think that you have a uterine infection. If it’s
necessary, the procedure can also be done to decrease the amount of amniotic
fluid in your womb.
Is Amniocentesis Performed?
This test is an outpatient procedure, so you won’t need to stay
in the hospital. Your doctor will first perform an ultrasound to determine the
exact location of your baby in your uterus. An ultrasound is a noninvasive
procedure that uses high-frequency sound waves to create an image of your
unborn baby. Your bladder must be full during the ultrasound, so drink plenty
of fluids beforehand.
After the ultrasound, your doctor may apply numbing medication to
an area of your belly. The ultrasound results will give them a safe location to
insert the needle. Then, they’ll insert a needle through your belly and into
your womb, withdrawing a small amount of amniotic fluid. This portion of the
procedure usually takes about two minutes.
The results of genetic tests on your amniotic fluid are usually
available within a few days. The results of tests to determine the maturity of
your baby’s lungs are usually available within a few hours.
Are the Complications Associated with Amniocentesis?
Amniocentesis usually occurs between 16 to 20 weeks, which is
during your second trimester. Complications associated with amniocentesis
include the following:
- The risk of miscarriage is 0.6
percent if you have the procedure during the second trimester. The risk is
if the test occurs before 15 weeks of pregnancy.
- Some women get cramps after the procedure.
- Some women have a small amount of vaginal
bleeding after the procedure.
- Rarely, amniocentesis may cause amniotic fluid
to leak out of your body.
- Another rare complication is a uterine
- If you have an infection such as hepatitis C or
HIV, amniocentesis can cause the infection to transfer to your unborn baby.
In rare cases, this test may cause some of your baby’s blood
cells to enter your bloodstream. This is important because there’s a type of
protein called the Rh factor. If you have this protein, your blood is Rh-positive.
If you don’t have this protein, your blood is Rh-negative. It’s possible for
you and your baby to have different Rh classifications. If this is the case and
your blood mixes with your baby’s blood, your body may react as if it were
allergic to your baby’s blood. If this happens, your doctor will give you a
drug called RhoGAM. This medication will prevent your body from making
antibodies that will attack your baby’s blood cells.
Do the Test Results Mean?
If the results of your amniocentesis are normal, your baby most
likely doesn’t have genetic or chromosomal abnormalities. In the case of
maturity amniocentesis, normal test results will assure you that your baby is
ready to be born with a high likelihood for survival.
Abnormal results may mean that your baby has a genetic problem or
serious birth defect. Discuss all test results with your doctor and your
partner so that you can make an informed decision about whether or not to
continue your pregnancy. This is a difficult time for parents, so seek support
from your loved ones, your doctor, or a support group.