Fetal blood sampling
Who gets the test?
Fetal blood sampling is used
to detect congenital malformations. This is not a standard test. Doctors may
suggest it if previous tests have given unclear results.
What does the test do
Fetal blood sampling can rule out
some congenital malformations. It may also show anemia and infections such as
rubella.
Fetal blood collection poses a
risk of miscarriage and other problems. The risk is higher than with similar
tests such as amniocentesis and chorionic villus sampling. Discuss the pros and
cons with your doctor.
How the test works
Using an ultrasound to see an
image of your baby, the doctor will pass a thin needle through the uterus and
into your baby's tiny blood vessel or umbilical cord. Your doctor will take a
small sample of your child's blood. You may feel some pressure or spasms. The
lab will then test the sample.
The procedure has different
names depending on how your doctor receives the blood. When a doctor collects
blood from the umbilical cord, it is called a percutaneous cord blood collection.
What you need to know about test results
Test results usually arrive
within three days. If they show that your child has a problem, you will meet
with your doctor or counselor to discuss your options. If your child has an
infection or anemia, treatment may help. Fetal blood sampling is an accurate
method for diagnosing certain birth defects. However, this does not show how
serious they are.
How often is a test done during pregnancy?
If you need a fetal blood sample, you will probably receive one around 17-18 weeks. This will depend on the reason for the test, such as anemia or infection. This can also be done at any time and possibly multiple times.