Podcast
Questions and Answers
What is the primary reason for using Rh-negative red blood cells in intrauterine transfusion?
What is the primary reason for using Rh-negative red blood cells in intrauterine transfusion?
- They cannot be hemolyzed by IgG Rh antibodies that cross the placenta. (correct)
- They have a higher oxygen-carrying capacity than Rh-positive cells.
- They stimulate a stronger fetal immune response.
- They are more compatible with the maternal immune system.
What is the effect of administering 300 µg of IgG Rhogam at 28 weeks of gestation?
What is the effect of administering 300 µg of IgG Rhogam at 28 weeks of gestation?
- It causes significant hemolysis in the fetus.
- It leads to an increase in fetal antibodies.
- It raises the maternal titer in the indirect Coombs test to 1:4. (correct)
- It lowers the risk of alloimmunization in the mother.
What does a negative indirect Coombs test indicate in an Rh-negative pregnant woman?
What does a negative indirect Coombs test indicate in an Rh-negative pregnant woman?
- She has high levels of IgM anti-Rh antibodies.
- She has no antibodies against Rh-positive cells. (correct)
- She is alloimmunized against Rh-positive cells.
- She has developed IgG anti-Rh antibodies.
If an Rh-negative woman's serum agglutinates Rh-positive cells in saline but shows a negative indirect Coombs test, what type of antibodies does she have?
If an Rh-negative woman's serum agglutinates Rh-positive cells in saline but shows a negative indirect Coombs test, what type of antibodies does she have?
What is a potential next step for an Rh-negative woman tested for Rh antibodies who shows IgM reactions?
What is a potential next step for an Rh-negative woman tested for Rh antibodies who shows IgM reactions?
Why is it important to monitor the indirect Coombs test in Rh-negative women with IgM antibodies?
Why is it important to monitor the indirect Coombs test in Rh-negative women with IgM antibodies?
What is a key distinction between IgM and IgG anti-Rh antibodies in relation to pregnancy?
What is a key distinction between IgM and IgG anti-Rh antibodies in relation to pregnancy?
What primary mechanism leads to the destruction of red blood cells coated with Rh antibodies?
What primary mechanism leads to the destruction of red blood cells coated with Rh antibodies?
Which IgG subclasses are primarily responsible for binding to high-affinity Fcγ receptors?
Which IgG subclasses are primarily responsible for binding to high-affinity Fcγ receptors?
What effect does the aggregation of antibodies have on their ability to bind to Fc receptors?
What effect does the aggregation of antibodies have on their ability to bind to Fc receptors?
Why does the risk of Rh alloimmunization decrease when the mother and father are ABO incompatible?
Why does the risk of Rh alloimmunization decrease when the mother and father are ABO incompatible?
What is a key distinction between bound and free immunoglobulin in the context of Fc receptor binding?
What is a key distinction between bound and free immunoglobulin in the context of Fc receptor binding?
What condition enhances the likelihood of fetal red blood cells surviving in maternal circulation?
What condition enhances the likelihood of fetal red blood cells surviving in maternal circulation?
What role do Kupffer cells play in the context of Rh antibody-coated red blood cells?
What role do Kupffer cells play in the context of Rh antibody-coated red blood cells?
What is the consequence of fetal red blood cells entering the maternal circulation in an ABO incompatible scenario?
What is the consequence of fetal red blood cells entering the maternal circulation in an ABO incompatible scenario?
Flashcards
Mechanism of Rh-positive red blood cell destruction
Mechanism of Rh-positive red blood cell destruction
Rh-positive red blood cells coated with Rh antibody adhere to macrophage Fc receptors (like CD64) in the spleen and liver. Macrophages then destroy these antibody-coated cells.
Why different ABO types affect Rh alloimmunization risk
Why different ABO types affect Rh alloimmunization risk
If mother and fetus have different ABO types, the fetal blood cells are quickly destroyed by the mother's ABO antibodies. This prevents the mother's immune system from recognizing and being sensitized to the Rh factor. Therefore, the risk of alloimmunization is lower.
Role of IgG subclasses in Rh destruction
Role of IgG subclasses in Rh destruction
IgG3 and IgG1 subclasses of Rh antibodies bind tightly to Fcγ receptors (like CD64) on macrophages leading to efficient red blood cell destruction.
Difference between free and bound antibody
Difference between free and bound antibody
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Fc Receptors
Fc Receptors
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ABO compatibility and Rh alloimmunization risk
ABO compatibility and Rh alloimmunization risk
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Rh alloimmunization
Rh alloimmunization
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Hemolytic disease of the newborn
Hemolytic disease of the newborn
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Rh-negative red blood cells
Rh-negative red blood cells
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RhoGam dosage safety
RhoGam dosage safety
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IgM anti-Rh antibodies
IgM anti-Rh antibodies
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Negative indirect Coombs test
Negative indirect Coombs test
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Agglutination in saline
Agglutination in saline
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IgG Rh antibodies
IgG Rh antibodies
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Monitoring Rh-negative patients
Monitoring Rh-negative patients
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Study Notes
Rh Alloimmunization and Hemolytic Disease of the Newborn
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Mechanism of Red Blood Cell Destruction:
- Rh antibodies coat red blood cells.
- Antibody-coated red cells adhere strongly to Fc receptors on macrophages (e.g., in the spleen and liver).
- IgG3 and IgG1 subclasses of antibodies bind most tightly to high-affinity Fcγ receptors (CD64).
- Macrophages engulf and destroy antibody-coated red blood cells, similar to how they destroy bacteria.
- Antigen binding and aggregation increase affinity for Fc receptors; free antibodies cannot bind.
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ABO Compatibility and Rh Alloimmunization Risk:
- ABO-compatible mothers have a higher risk (16%) of Rh alloimmunization compared to ABO-incompatible mothers (7%).
- If mother and fetus have the same ABO type, fetal blood persists longer in the mother.
- If mothers have ABO antibodies, fetal red blood cells are rapidly destroyed, hindering alloimmunization.
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Intrauterine Transfusion Cells:
- Rh-negative red blood cells are used in intrauterine transfusions to avoid hemolysis by maternal IgG Rh antibodies.
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RhoGAM Administration:
- Administering RhoGAM (300 µg IgG) at 28 weeks of gestation is safe as the amount is insufficient to harm the fetus.
- This amount of antibody does not harm the fetus and raises the maternal titer in the indirect Coombs test to 1:4 if the mother is already immunized by a previous fetus.
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Interpretation of Coombs Test Results:
- Negative indirect Coombs test in a pregnant Rh-negative woman indicates no IgG anti-Rh antibodies.
- Serum agglutination of Rh-positive cells in saline suggests IgM anti-Rh antibodies.
- IgM antibodies do not cross the placenta and pose no immediate risk.
- Repeated testing is required to rule out potential development of IgG antibodies.
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Description
Explore the mechanisms of Rh alloimmunization and the implications of hemolytic disease in newborns. This quiz covers topics such as the destruction of red blood cells by antibodies and the importance of ABO compatibility. Delve into the clinical aspects and risks associated with these conditions.
