Fetal Blood Sampling

What Is Fetal Blood Sampling (FBS)?

It is a procedure in which an obstetrician withdraws blood from the umbilical cord of the fetus.

This is done by inserting a thin hollow needle through the mother's abdomen into the umbilical cord. The obstetrician will use ultrasound to guide the needle during the procedure so as not to harm the unborn child.

The procedure is performed on an outpatient basis and takes only a few minutes.

The needle will cause some pain when it penetrates the uterus, but the pain should not last long and should not hurt more than an injection into any other part of the body.

After the fetal blood has been withdrawn, the removal of the needle should cause no further discomfort. The fluid is then sent to the laboratory for special tests.

Why Is Fetal Blood Sampling Necessary?

The majority of fetal blood sampling is done for the detection of chromosomal disorders, genetic diseases and viral infection.

Chromosomes carry genes that pass certain characteristics from parents to their children. When there are too many or two few chromosomes, or there is a defect in a chromosome, birth defects usually occur.

Down Syndrome is the most common chromosomal disorder. It causes mental retardation and other health problems such as heart defects. Other less common chromosomal disorders may lead to serious handicaps and death.

When Is Fetal Blood Sampling Done?

Fetal Blood Sampling is usually done between 20th and 23rd week of pregnancy.

When Will The Fetal Blood Sampling Test Results Be Available?

Usually it takes about 1 - 2 weeks to complete the laboratory test.

Can All Birth Defects Be Detected By Fetal Blood Sampling?

No. Fetal blood sampling can detect almost all known chromosomal disorders. It can also check for specific genetic disease and viral infections.

Who Should Consider Fetal Blood Sampling?

• Any patient with fetal abnormalities detected during ultrasound screening.
• Any patient who is more than 20 weeks pregnant and is at high risk of having a chromosomal disorder.
• If both parents are thalassaemia carriers.

There may be other reasons that apply uniquely to you. Both you and your obstetrician should decide together if you need a fetal blood sampling.

Is Fetal Blood Sampling Safe?

Fetal blood sampling is a safe, low risk procedure when done by experienced medical experts. The risk of miscarriage following the test is reported to be 2 - 5%.

Useful Information

Return To The Hospital Or Call Your Obstetrician If :

• You run a fever
• You feel nauseated and vomit
• You experience pain in the shoulder
• You experience any unusual lower abdominal pain
• You notice vaginal bleeding
• You notice leakage of fluid from the vagina