A rubella blood test detects antibodies that are made by the immune system to help kill the rubella virus. These antibodies remain in the bloodstream for years. The presence of certain antibodies means a recent infection, a past infection, or that you have been vaccinated against the disease.
Rubella (also called German measles or 3-day measles) usually does not cause long-term problems. But a woman infected with the rubella virus during pregnancy can transmit the disease to her baby (fetus). And serious birth defects called congenital rubella syndrome (CRS) could develop, especially during the first trimester. Birth defects of CRS include cataracts and other eye problems, hearing impairment, and heart disease. Miscarriage and stillbirth are also possible consequences for pregnant women. The vaccination to prevent rubella protects against these complications.
A rubella test is usually done for a woman who is or wants to become pregnant to determine whether she is at risk for rubella. Several laboratory methods can be used to detect rubella antibodies in the blood. The most commonly used method is the enzyme-linked immunosorbent assay (ELISA, EIA).
Why It Is Done
A test for rubella is done to find out if:
Some babies born with birth defects may be tested for congenital rubella.
How To Prepare
No special preparation is required before having this test.
How It Is Done
The health professional taking a sample of your blood will:
How It Feels
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having a blood sample taken from a vein.
A rubella blood test detects antibodies that are made by the immune system to help kill the rubella virus. The test for IgG antibodies is most common and is the test done to see if a woman who is pregnant or planning to get pregnant is immune to rubella.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
A test for rubella IgM antibodies is done only if the doctor suspects you have a current rubella infection. More than 1.1 IU/mL IgM antibodies means you had a recent rubella infection or you have a current infection.1
What Affects the Test
There are no factors that would interfere with the test or the accuracy of the results.
What To Think About
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