Cordocentesis
Cordocentesis, also
sometimes called percutaneous cord blood sampling, is a diagnostic test that
examines the blood of the fetus to look for abnormalities in the fetus.
How is cordocentesis performed?
Advanced ultrasound
imaging determines where the umbilical cord inserts into the placenta. An
ultrasound guides a thin needle through the abdomen and uterine wall to the
umbilical cord. A needle is inserted into the umbilical cord to take a small
sample of the fetus's blood.
The sample is sent to
a lab for analysis and results are usually available within 72 hours.
The procedure is
similar to amniocentesis, except that the goal is to take fetal blood rather
than amniotic fluid.
When is cordocentesis performed?
Cordocentesis is
usually performed when diagnostic information cannot be obtained by
amniocentesis, chorionic villus sampling, or ultrasound, or when the results of
these tests are inconclusive. Cordocentesis is performed after 17 weeks of
pregnancy.
What is cordocentesis looking for?
Cordocentesis detects
chromosomal abnormalities (Down's syndrome) and blood disorders (hemolytic
disease of the fetus).
Cordocentesis may be
performed to help diagnose any of the following problems:
- Malformations of the fetus
- Fetal infection (toxoplasmosis or rubella)
- Fetal platelet count in the mother
- Fetal anemia
- Isoimmunisation
This test differs
from amniocentesis in that it does not check for neural tube defects.
What do the results of cordocentesis mean?
Cordocentesis is a
diagnostic test that detects chromosomal abnormalities and some blood disorders
with high accuracy. Although the probability of identification is high, this
test does not measure the severity of these disorders. This test also fails to
detect neural tube defects.
What are the risks and side effects for the mother or baby?
Although
cordocentesis is considered a safe procedure, it is recognized as an invasive
diagnostic test with potential risks. Miscarriage is the main risk associated
with cordocentesis, occurring 1 to 2 times in 100 procedures.
Other potential side
effects include:
- Blood loss from the puncture site
- Infection
- Drop in fetal heart rate
- Premature rupture of membranes
- Contact your doctor if these symptoms remain or get worse.
You should also see
your doctor if you experience:
- Fever
- Chills
- Leaking of amniotic fluid
What are the reasons to test or not to test?
Reasons for testing
or not testing vary from person to person, couple to couple, and doctor to
doctor.
Performing tests and
confirming the diagnosis gives you certain options:
- Pursue potential medical interventions that may exist
- Begin planning for a child with special needs
- Start addressing anticipated lifestyle changes
- Identify support groups and resources
Some individuals or
couples may refuse to be tested or additional tested for a number of reasons:
- They are satisfied with the results, regardless of the outcome
- For personal, moral or religious reasons, deciding to carry a child to term is not an option.
Some parents choose not to allow tests that could harm a developing child.