Podcast
Questions and Answers
What is the primary reason why hyperbilirubinemia becomes apparent only in the delivered newborn?
What is the primary reason why hyperbilirubinemia becomes apparent only in the delivered newborn?
In which scenario does hemolysis associated with ABO incompatibility typically occur?
In which scenario does hemolysis associated with ABO incompatibility typically occur?
What is the primary reason for the low incidence of alloimmunization in ABO incompatibility?
What is the primary reason for the low incidence of alloimmunization in ABO incompatibility?
What subtype of antibodies is initially produced by the maternal immune system after exposure to a foreign antigen?
What subtype of antibodies is initially produced by the maternal immune system after exposure to a foreign antigen?
Signup and view all the answers
What is the approximate incidence of ABO incompatibility per 10,000 live births?
What is the approximate incidence of ABO incompatibility per 10,000 live births?
Signup and view all the answers
What is the characteristic feature of spherocytosis in ABO incompatibility?
What is the characteristic feature of spherocytosis in ABO incompatibility?
Signup and view all the answers
What is the primary site of fetal erythropoiesis in response to severe anemia?
What is the primary site of fetal erythropoiesis in response to severe anemia?
Signup and view all the answers
What is the primary cause of late anemia in hemolytic disease of the newborn?
What is the primary cause of late anemia in hemolytic disease of the newborn?
Signup and view all the answers
What is the result of ABO-incompatible RBCs in the maternal circulation?
What is the result of ABO-incompatible RBCs in the maternal circulation?
Signup and view all the answers
What is the primary laboratory feature of hemolytic disease of the newborn?
What is the primary laboratory feature of hemolytic disease of the newborn?
Signup and view all the answers
What is the consequence of prolonged hemolysis in a fetus?
What is the consequence of prolonged hemolysis in a fetus?
Signup and view all the answers
What is the primary imaging study used to detect fetal anemia?
What is the primary imaging study used to detect fetal anemia?
Signup and view all the answers
What is the fate of antibody-coated RBCs in the reticuloendothelial system?
What is the fate of antibody-coated RBCs in the reticuloendothelial system?
Signup and view all the answers
What is the consequence of severe hemolysis in a fetus?
What is the consequence of severe hemolysis in a fetus?
Signup and view all the answers
What is the primary management strategy for hemolytic disease of the newborn?
What is the primary management strategy for hemolytic disease of the newborn?
Signup and view all the answers
What is the primary method of prevention of Rh sensitization?
What is the primary method of prevention of Rh sensitization?
Signup and view all the answers
What is the source of unconjugated bilirubin in a fetus with severe hemolysis?
What is the source of unconjugated bilirubin in a fetus with severe hemolysis?
Signup and view all the answers
What is the relationship between the amount of fetomaternal hemorrhage and Rh sensitization of the mother?
What is the relationship between the amount of fetomaternal hemorrhage and Rh sensitization of the mother?
Signup and view all the answers
What is the primary cause of severe hemolytic disease of the newborn?
What is the primary cause of severe hemolytic disease of the newborn?
Signup and view all the answers
What is the likelihood of an Rh-positive child being born to an Rh-negative mother?
What is the likelihood of an Rh-positive child being born to an Rh-negative mother?
Signup and view all the answers
What is the main mechanism of Rh sensitization during pregnancy?
What is the main mechanism of Rh sensitization during pregnancy?
Signup and view all the answers
What is the frequency of Rh negativity in Whites?
What is the frequency of Rh negativity in Whites?
Signup and view all the answers
What is the consequence of hemolysis in newborns?
What is the consequence of hemolysis in newborns?
Signup and view all the answers
What is the role of ABO incompatibility in hemolytic disease of the newborn?
What is the role of ABO incompatibility in hemolytic disease of the newborn?
Signup and view all the answers
What is the typical volume of fetomaternal hemorrhage during pregnancy?
What is the typical volume of fetomaternal hemorrhage during pregnancy?
Signup and view all the answers
Which of the following procedures increases the risk of alloimmunization?
Which of the following procedures increases the risk of alloimmunization?
Signup and view all the answers
Study Notes
Hemolytic Disease of the Newborn (HDN)
- Hyperbilirubinemia becomes apparent only in the delivered newborn because the placenta effectively metabolizes bilirubin.
- Hemolysis associated with ABO incompatibility exclusively occurs in type-O mothers with fetuses who have type A or type B blood.
Pathogenesis of ABO Incompatibility
- It has rarely been documented in type-A mothers with type-B infants with a high titer of anti-B IgG.
- In mothers with type A or type B, naturally occurring antibodies are of the IgM class and do not cross the placenta.
- 1% of type-O mothers have a high titer of the antibodies of IgG class against both A and B, which cross the placenta and cause hemolysis in the fetus.
- The reason for the low incidence of alloimmunization in ABO incompatibility is that ABO antigen is widely expressed in other tissues but less expressed on the surface of fetal RBC.
Epidemiology of ABO Incompatibility
- The incidence is 45 per 10,000 live births.
- The prevalence is 6-7 per 1000 live births.
- It is rare in Nigeria, probably because of the presence of an RhD pseudogene in Africans.
Comparison of Rh and ABO Incompatibility
- Stillborn/hydrops are frequent in Rh incompatibility and rare in ABO incompatibility.
- Severe anemia is frequent in Rh incompatibility and rare in ABO incompatibility.
- Jaundice is moderate to severe and frequent in Rh incompatibility, but mild in ABO incompatibility.
- Late anemia is frequent in Rh incompatibility and rare in ABO incompatibility.
Clinical Features of HDN
- Anemia
- Jaundice
- Hepatosplenomegaly
- Kernicterus
- Late anemia, caused by:
- Erythropoietin suppression
- Continued cell lysis by maternal antibodies
Laboratory Features of HDN
- FBC:
- Increased nucleated RBCs
- Reticulocytosis
- Polychromasia
- Anisocytosis
- Spherocytes
- Cell fragmentation
- Coombs test:
- Direct
- Indirect
- Imaging studies:
- Ultrasonography
- Doppler (MCA blood flow velocity) for detection of fetal anemia
- Rh grouping and genotyping
- Kleihauer-Betke test
- Optical density measurement
Management of HDN
- Intrauterine blood transfusion:
- Intraperitoneal transfusion
- Intravenous transfusion
- Phototherapy
- Intravenous immunoglobulin (IVIG)
- Exchange blood transfusion
Prevention of HDN
- Rh immunoglobulin at 28 weeks and within 72 hours of delivery
- Also administer RhIG to unsensitized Rh-negative women
Pathogenesis of Rh Incompatibility
- After the initial exposure to a foreign antigen, B-lymphocyte clones that recognize the RBC antigen are established.
- The maternal immune system initially produces antibodies of the IgM isotype that do not cross the placenta.
- Later, produces antibodies of the IgG isotype that traverse the placental barrier.
- Predominant antibody subclass appears to be IgG1 in one-third of individuals, whereas a combination of IgG1 and IgG3 subclasses are found in the remaining individuals.
- The ABO-incompatible RBCs are rapidly destroyed in the maternal circulation, reducing the likelihood of exposure to the immune system.
- The degree of Rh sensitization of the mother is directly related to the amount of fetomaternal hemorrhage.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the pathogenesis of hyperbilirubinemia in newborns, including the role of placenta and hemolysis associated with ABO incompatibility.
