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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).
A test for rubella is done to find out if:
Some babies born with birth defects may be tested for congenital rubella.
No special preparation is required before having this test.
The health professional taking a sample of your blood will:
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.
More than 10 international units per millilitre (IU/mL) IgG antibodies. A positive rubella IgG test result is good—it means that you are immune to rubella and cannot get the infection. This is the most common rubella test done.
Less than 7 IU/mL IgG antibodies and less than 0.9 IgM antibodies. This means you are not immune to rubella. If you are a woman thinking about getting pregnant, talk with your doctor about getting a rubella vaccine before pregnancy.
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.footnote 1
There are no factors that would interfere with the test or the accuracy of the results.
CitationsFischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.Other Works ConsultedChernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Current as of: May 27, 2020
Author: Healthwise StaffMedical Review: John Pope MD - PediatricsAnne C. Poinier MD - Internal MedicineE. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineKathleen Romito MD - Family MedicineW. David Colby IV MSc, MD, FRCPC - Infectious DiseaseChristine Hahn MD - Epidemiology
Current as of: May 27, 2020
Author: Healthwise Staff
Medical Review:John Pope MD - Pediatrics & Anne C. Poinier MD - Internal Medicine & E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine & W. David Colby IV MSc, MD, FRCPC - Infectious Disease & Christine Hahn MD - Epidemiology
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