rubella hemagglutination inhibition (HI) test

ru·bel·la he·mag·glu·ti·na·tion in·hi·bi·tion (HI) test

(rū-bel'lă hē'mă-glū-ti-nā'shŭn in'hi-bish'ŭn test)
A serum test to determine a person's state of immunity against rubella, often performed routinely as part of a prenatal workup of a pregnant woman because the disease during pregnancy carries significant risks for the fetus. Generally, a rubella titer of 1:10 or higher means that the person has developed immunity to rubella.