Rubella Test – Why am I having this test?

Rubella test checks for the viral infection rubella. Rubella is also known as German measles. It usually causes a mild fever and rash. You may have this test:

• If you are pregnant or trying to become pregnant. The rubella virus poses the greatest risk to an unborn baby (fetus). If a pregnant woman passes rubella to her fetus, it can cause congenital rubella syndrome (CRS).
• This can result in problems that are present in the baby at birth (congenital defects), such as heart defects or delayed development.
• If you have symptoms of rubella, such as:
  • Fever.
  • Headache.
  • Runny nose.
  • Rash.
• To confirm that you are protected against (immune to) the rubella virus. There is a vaccine that protects against rubella, but the protection from the virus (immunity) can wear off (be inadequate) after having the vaccine.

A newborn may need a rubella test if he or she has signs of CRS, or if the mother had rubella during the pregnancy.

What is being tested?

This test checks the blood for the presence of:

• IgG (immunoglobulin G) antibodies.
• IgM (immunoglobulin M) antibodies.

Antibodies are cells that are part of the body’s disease-fighting system (immune system). After you get an infection, your body makes antibodies that stay in your body after you recover and protect you from getting the same infection again.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel. If you may have a current (active) infection, a swab of fluid from your throat or nose may also be tested (cultured) to confirm the diagnosis.

For babies, blood may be taken through the umbilical cord or through a needle prick in the back of the foot (heel stick).

Tell a health care provider about:

• Any allergies you have.
• All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
• Any blood disorders you have.
• Any surgeries you have had.
• Any medical conditions you have.
• Whether you are pregnant or may be pregnant.

How are the results reported?

Your test results will be reported as either positive or negative for each antibody. Positive means that you have the antibody, and negative means that you do not have the antibody.

If you have a positive result for only IgG antibodies, it will also be reported as a ratio (titer) that indicates how much immunity you have.

What do the results mean?

• A negative result for both antibodies is considered normal. This result means that you do not have rubella and you are not immune to rubella. You may not have gotten the vaccine, or you may not have responded to the vaccine as a child.
  • If you are planning a pregnancy, it is recommended that you get vaccinated before trying to become pregnant. Wait at least a month after receiving the vaccine before becoming pregnant.
  • Pregnant women should not receive the rubella vaccine.
• Positive for only IgG antibodies with a titer of 1:20 or greater means that you are immune to rubella. You may have had rubella in the past, or you may have had the rubella vaccine.
• Positive for only IgG antibodies with a titer of 1:8 or less means that you have inadequate immunity. In newborns, this result means that the baby was not infected with the virus before birth (in utero), but the baby did receive immunity from the mother in utero. The baby will still need the rubella vaccine at the appropriate age.
• Positive for only IgM antibodies may mean that you have an active or recent rubella infection. In newborns, this result means that the baby was exposed to the rubella virus in utero and is at risk for CRS.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• Rubella is a viral infection, also known as German measles. The rubella test checks for this virus in your body.
• You may have this test if you are pregnant or trying to become pregnant. The rubella virus can cause congenital rubella syndrome (CRS) in an unborn baby (fetus). This can result in problems that are present in the baby at birth (congenital defects).
• A positive test may indicate prior immunization, current (active) infection, or a recent infection. Talk with your health care provider about what your results mean.