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16. A 25-year-old woman, gravida 1, para 0, who is Rh-negative, delivers a full-term Rh-positive neonate. The mother is given prophylactic anti-Rho(D) immune globulin immediately post partum. During her second pregnancy 3 years later, she is screened each trimester for Rho(D) antibodies. An indirect antiglobulin test done during the third trimester indicates the presence of anti-Rho(D) antibodies in her serum. Which of the following is the most likely mechanism for the occurrence of these maternal antibodies?
A ) Anamnestic production of maternal anti-Rho(D) immunoglobulin
B ) Intrauterine transplacental fetal-maternal hemorrhages during the second pregnancy
C ) Residual circulating prophylactic anti-Rho(D) immunoglobulin
D ) Transplacental passage of fetal IgG anti-Rho(D) antibodies
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B. intrauterine transplacental fetal-maternal hemorrhages during the second pregnancy.
"The mother is given prophylactic anti-Rho(D) immune globulin immediately post partum. During her second pregnancy 3 years later, she is screened each trimester for Rho(D) antibodies. An indirect antiglobulin test done during the third trimester indicates the presence of anti-Rho(D) antibodies in her serum"
That means, the first two trimester, antibody is negative. A is not right.
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Arya,
Would you plz explain it. how did you figure it out ?
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"The mother is given prophylactic anti-Rho(D) immune globulin immediately post partum. During her second pregnancy 3 years later, she is screened each trimester for Rho(D) antibodies. An indirect antiglobulin test done during the third trimester indicates the presence of anti-Rho(D) antibodies in her serum"
That means, during the second pregnancy, the first two trimester, antiglobulin test is negative, so A and c are not right, otherwise the result won't be negative, but possitive.
New onset of positive anti Rh D antibodies means there is mixing of mom's blood and fetus's blood. That is why B is right.
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hey arya
What u say makes sense,but isnt it that even if there are heamorhages and mixing of blood,still there wont be some new form of antibodies produced.The memory cells will still be activated and form the same response.So isnt it that the basic resonse is still the memory cells and prodution of familiar response.
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Since D isoimmunization during pregnancy is caused by transplacental hemorrhage, the risk of isoimmunization increases whenever such hemorrhage is likely to occur, including after abortion, amniocentesis, chorionic villus sampling (CVS), cordocentesis, ectopic pregnancy, fetal manipulation (e.g., external version procedures) or surgery, antepartum hemorrhage, antepartum fetal death, and stillbirth.
http://cpmcnet.columbia.edu/texts/gcps/gcps0048.html.
U r right.
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