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 method