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What is the most likely cause of severe long-term neurological impairment in children treated with intrauterine transfusion (IUT)?
What is the main reason for the decrease in the rate of RBC destruction after birth?
What is the half-life of IgG in the infant's circulation?
Which type of anemia is characterized as occurring within 7 days of birth?
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What contributes to late hypo regenerative anemia in affected newborns?
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What causes neonatal jaundice after birth?
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What is the significance of the Direct Antiglobulin Test (DAT) in diagnosing ABO HDFN?
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What Hb level indicates a need for cordocentesis blood sample?
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What can untreated high bilirubinemia lead to in neonates?
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What is the initial intrauterine transfusion typically repeated to manage?
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Which test can show a positive result even in the absence of clinical anemia in newborns?
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What is a recommended procedure for collecting cord blood samples?
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Which of the following characteristics is not typical for RBCs used in intrauterine transfusions?
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What is a significant risk associated with cordocentesis and intrauterine transfusion?
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What should be investigated if the DAT result is negative but the infant is jaundiced?
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What type of bilirubin is found in excess leading to neonatal jaundice?
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What best describes the potential outcomes for children treated with intrauterine transfusion?
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What is the recommended frequency for repeating intrauterine transfusions until delivery?
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What happens to hemoglobin released from RBC destruction during the neonatal period?
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Which factor can complicate the search for RBCs for intrauterine transfusion?
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What is the chance of adverse fetal events when performing intrauterine transfusion alone?
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What should be monitored after a two-volume exchange transfusion?
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What is the purpose of phototherapy in newborns?
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Which treatment for hyperbilirubinemia reduces hemolysis caused by maternal antibodies?
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What generally happens to the bilirubin levels after a two-volume exchange transfusion?
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What characteristic must RBC units have for infants receiving top-off transfusions?
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Which of the following is a primary measure to prevent HDFN?
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Why should RhD negative RBCs be preserved in blood bank inventory?
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What is not affected by the use of IVIG?
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What test is used to quantify fetal cells in maternal blood?
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What is the role of maternal blood volume in calculating fetomaternal hemorrhage?
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What defines Weak D phenotypes in RhD typing?
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How many vials of RhIG are required after calculating the fetomaternal hemorrhage volume?
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Which assay may provide more accurate quantitation of fetomaternal hemorrhage compared to Kleihauer-Betke?
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In what time frame should additional vials of RhIG be administered after delivery if necessary?
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Which of the following is NOT considered a cause of differential diagnosis related to blood disorders?
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What characterizes the fetal cells during the Kleihauer-Betke test?
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Study Notes
Pathogenesis of HDFN
- IgG antibodies are responsible for RBC destruction in HDFN
- IgG crosses the placenta and binds to fetal RBCs
- Maternal antibodies persist in newborn infant's circulation after birth
- Antibody-mediated hemolysis continues for several days or weeks after delivery
Phases of Anemia in HDFN
- Early hemolytic anemia: Occurs within 7 days of birth
- Late hemolytic anemia: Occurs 2 weeks or more after birth
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Late hyporegenerative anemia: Associated with transfusions and IU
- Marrow suppression due to antibody destruction of RBC precursors and erythropoietin deficiency
Neonatal Manifestations of HDFN-Induced Anemia
- Severity of anemia varies depending on the time of onset
- Infants with severe anemia are more likely to have long-term neurological impairment
Bilirubin
- Hemoglobin is metabolized to bilirubin after RBC destruction.
- Unconjugated bilirubin is water-insoluble and transported to the liver to be conjugated and excreted.
- Infant liver's inability to efficiently metabolize bilirubin can lead to unconjugated bilirubin accumulation and neonatal jaundice.
- High bilirubin levels can cause kernicterus, leading to permanent brain damage.
Postnatal Diagnosis of HDFN
- No single serologic test is diagnostic for ABO HDFN
- Direct antiglobulin test (DAT) on cord or neonatal RBCs is crucial
- DAT can be positive even in the absence of clinical anemia.
- Cord blood samples should be collected by venipuncture to avoid maternal blood contamination
Intrauterine Transfusion (IUT)
- Goal of IUT is to maintain fetal hemoglobin above 10 g/dL.
- IUT is typically repeated every 2 to 4 weeks until delivery.
- Initial IUT is rarely performed after 36 weeks' gestation.
- IUT carries risks including infection, premature labor, and placental trauma
- High-level antigen matching may reduce the risk of further alloimmunization, but finding compatible RBCs is challenging.
- Despite risks, children treated with IUT have a relatively low rate of neurocognitive impairment if they were not severely hydropic.
Exchange Transfusion
- Replaces infant's blood with RBC unit mixed with plasma to create reconstituted whole blood.
- Reduces bilirubin levels
- Monitoring for iatrogenic thrombocytopenia is essential after the procedure.
Simple Transfusions
- Small-volume or 'top-off' RBC transfusions used to correct anemia.
- Infants should be monitored for clinical signs of anemia.
- RBCs used for transfusion have similar attributes as those used for IUT and exchange transfusion.
Phototherapy
- Used to metabolize unconjugated bilirubin to isomers less lipophilic and less toxic to the brain.
- Effective for infants with mild to moderate hemolysis.
Intravenous Immune Globulin (IVIG)
- Treats hyperbilirubinemia of the newborn caused by HDFN.
- IVIG competes with maternal antibodies for Fc receptors on macrophages, reducing hemolysis.
- May reduce the need for transfusions, but does not affect the need for top-off transfusions.
Prevention of HDFN
- RhD negative RBCs should be reserved for women of childbearing potential.
- Matching minor blood group antigens is recommended for women of childbearing potential
- K-negative RBC units should be used for women younger than 45-50 years of age.
- Kleihauer-Betke test is used to estimate fetal-maternal hemorrhage (FMH) volume
- Flow cytometry provides more accurate quantification of FMH volume.
- RhD genetic testing is encouraged for patients with a weak D phenotype.
Differential Diagnosis
- RBC enzyme disorders (e.g., G6PD deficiency)
- Disorders of hemoglobin synthesis (e.g., alpha-thalassemias)
- RBC membrane abnormalities (e.g., hereditary spherocytosis)
- Hemangiomas (Kasabach–Merritt syndrome)
- Acquired conditions (e.g., sepsis, TORCH infections)
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Description
This quiz explores the pathogenesis of Hemolytic Disease of the Fetus and Newborn (HDFN), focusing on how IgG antibodies lead to RBC destruction. It details the phases of anemia in HDFN, neonatal manifestations, and the role of bilirubin metabolism. Test your understanding of this critical topic in neonatal care!