Fetal blood sampling is a procedure to take a small amount of blood from an unborn baby (fetus) during pregnancy. Fetal blood sampling is usually done by a perinatologist with special training. This is a doctor who specializes in the care of babies in high-risk pregnancies.
Fetal blood sampling is a very complex procedure. It must be done by a doctor with special training. It’s done when other tests or procedures are not possible or do not work. It can be done for pregnancies that are 18 weeks or later.
Fetal blood sampling is done as part of diagnosing, treating, and checking problems in the baby at certain times during pregnancy. A fetal blood sample may be taken to:
Diagnose genetic or chromosome abnormalities
Check for and treat severe anemia in the baby
Check for and treat other blood problems such as Rh disease
Check oxygen levels in the baby
Check for infection in the baby
Give certain medicines to the baby
The benefits of fetal blood sampling include:
It gives specific information about the baby's health.
A baby with severe blood diseases can be treated before birth.
The risks of fetal blood sampling include:
Bleeding from the fetal blood sampling site
Changes in the baby’s heart rate
Leaking of amniotic fluid
Death of the baby
You don’t need to do any special preparation before the procedure. Your healthcare provider will tell you if you need to have a full bladder for the test.
You will lie in a comfortable position on an exam table. The healthcare provider will clean your belly with antiseptic. He or she will insert a long, thin needle through the belly and into the uterus. This is guided by ultrasound. Blood may be taken from several sites, such as:
Blood vessels in the umbilical cord. This is also called cordocentesis. It’s also known as percutaneous umbilical blood sampling (PUBS).
A blood vessel in the baby. This is usually in the liver or heart.
Fetal blood transfusions are done using a similar method. The baby either gets blood or has unhealthy blood exchanged for healthy blood. This can treat certain problems. In this case, it may be needed to give a sedative medicine to keep the baby from moving.
After the procedure, you’ll need to rest in the hospital. Your baby’s heart rate will be watched for a few hours. You’ll need to have someone drive you home afterward. The results will take several days. You’ll have a follow-up appointment with the perinatologist to discuss the results.
Before you agree to the test or the procedure make sure you know:
The name of the test or procedure
The reason you are having the test or procedure
What results to expect and what they mean
The risks and benefits of the test or procedure
What the possible side effects or complications are
When and where you are to have the test or procedure
Who will do the test or procedure and what that person’s qualifications are
What would happen if you did not have the test or procedure
Any alternative tests or procedures to think about
When and how you will get the results
Who to call after the test or procedure if you have questions or problems
How much you will have to pay for the test or procedure