A pregnant woman had contact with her nephew who was just diagnosed with a rubella infection. Acute and convalescent samples were taken, which resulted in an acute titer of 1:16 and a con-valescent titer of 1:32 . Which one of the following comments explains the risk to the fetus?
a. The risk is low; a fourfold rise in titer is not present.
b. The risk is high; more than a fourfold rise is present in titer.
c. The risk is high because both titers are elevated.
d. Rubella is not a congenital disease; there-fore the test should not have been ordered.
A
No fourfold rise is present in titer (two doubling dilutions); in addition, the pregnant woman is immune with a titer of greater than 1:8 . Therefore, the risk to the developing fetus is low since the pregnant woman has enough antibodies to cross the placenta and protect the fetus.
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