Neonatal Anemia and Jaundice Overview

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Questions and Answers

Which group of mothers is most likely to experience clinically significant ABO hemolytic disease of the fetus and newborn (HDFN)?

Group A mothers with group O infants

Group B mothers with group O infants

Group O mothers with group B infants (correct)

Group O mothers with group A infants (correct)

At what titer level of IgG anti-ABO antibodies is ABO HDFN more likely to occur?

256

> 1024 (correct)

< 256

512 (correct)

What is a common outcome for infants with ABO HDFN regarding their RBC antigen development?

ABO antigens are more active in infants than adults

ABO antigens are fully developed at birth

ABO antigens are well-developed by three months

ABO antigens are poorly developed at birth (correct)

Which of the following factors has been linked to the production of high-titered IgG ABO antibodies during pregnancy?

Tetanus toxoid administration Signup and view all the answers

What is a consequence of fetal-maternal hemorrhage (FMH)?

Increases throughout the pregnancy Signup and view all the answers

What is the likelihood of a Rh-negative individual forming anti-D antibodies after being transfused with Rh-positive RBCs?

85% will form anti-D Signup and view all the answers

Which of the following fetal duodenal conditions is extremely rare in ABO-induced HDFN?

Hydrops Signup and view all the answers

What genetic factor can influence an individual's ability to produce antibodies in response to antigenic exposure?

Genetic makeup Signup and view all the answers

What can be omitted in the initial antibody screening process?

Immediate temperature incubation Signup and view all the answers

Which type of antibodies may cause mild to moderate hemolytic disease of the fetus and newborn (HDFN)?

Anti-M Signup and view all the answers

What type of antibodies can be ignored in follow-up testing due to their non-pathogenic nature?

Cold reactive IgM antibodies Signup and view all the answers

How can the immunoglobulin class of antibodies be established?

Treating serum with a sulfhydryl reagent Signup and view all the answers

Which antibodies are common in pregnant women but not known to cause HDFN?

Lewis system antibodies Signup and view all the answers

What happens when serum containing IgM antibodies is treated with a sulfhydryl reagent?

IgM antibodies are destroyed Signup and view all the answers

If the antibody screen is reactive, what must be determined next?

The antibody identity Signup and view all the answers

What causes the accumulation of unconjugated bilirubin in newborns?

Inefficient metabolism of bilirubin by the immature liver Signup and view all the answers

In which trimester should Rh D-negative pregnant patients be screened for unexpected transfused antibodies?

First trimester Signup and view all the answers

Which diagnostic test is considered most important for identifying ABO HDFN in newborns?

Direct Antiglobulin Test (DAT) on the cord or neonatal RBCs Signup and view all the answers

What is a potential consequence of untreated high bilirubinemia in newborns?

Kernicterus leading to permanent brain damage Signup and view all the answers

Why should cord blood samples be collected by venipuncture?

To ensure it is free from maternal blood contamination Signup and view all the answers

What is the characteristic feature of unconjugated bilirubin?

Water-insoluble Signup and view all the answers

When jaundice appears in a newborn, what should be investigated?

Various potential causes of jaundice Signup and view all the answers

What role does the maternal liver play in bilirubin metabolism during pregnancy?

It conjugates indirect bilirubin and excretes it Signup and view all the answers

What signifies a positive DAT result in a newborn if anemia is not present?

Compensated anemia in the newborn Signup and view all the answers

What is the purpose of monitoring antibody titers in pregnant women with known RBC alloimmunization?

To assess the risk of fetal anemia Signup and view all the answers

What diagnostic method is primarily used to track fetal anemia during pregnancy?

Fetal middle cerebral artery peak systolic velocity Signup and view all the answers

At what gestational age is a fetal ultrasound recommended to begin monitoring fetal anemia?

16 to 20 weeks Signup and view all the answers

What is an indication for performing cordocentesis?

To measure fetal hematocrit levels Signup and view all the answers

What does an MCA-PSV measurement greater than 1.5 MoM indicate?

Significant fetal anemia Signup and view all the answers

What has replaced amniocentesis for monitoring fetal anemia risk?

MCA-PSV measurements Signup and view all the answers

When is intrauterine transfusion indicated for a fetus?

Presence of hydrops noted on ultrasound Signup and view all the answers

How is the concentration of bilirubin in amniotic fluid quantified?

Spectrophotometric scan at 450 nm Signup and view all the answers

What is the percentage reduction in the risk of an RhD-negative mother becoming allosensitized with the administration of RhIG?

0.1% Signup and view all the answers

When is the first dose of RhIG usually administered during pregnancy?

At 28 weeks’ gestation Signup and view all the answers

What should be done if more than 72 hours have passed after the delivery of an RhD-positive infant regarding RhIG administration?

RhIG can still be given Signup and view all the answers

Why is RhIG not indicated for a mother if the infant is found to be D-negative?

It's only needed for D-positive infants Signup and view all the answers

What is the effect of ghod administration of RhIG on maternal sensitization from previous pregnancies?

It reduces the risk Signup and view all the answers

What is the half-life of IgG in the context of RhIG?

25 days Signup and view all the answers

What can happen if intramuscular RhIG is administered intravenously?

It may cause severe anaphylactic reactions Signup and view all the answers

What is the purpose of screening a maternal sample using the rosette technique post-delivery?

To test for massive fetomaternal hemorrhage Signup and view all the answers

Study Notes

Neonatal Manifestations of HDFN-Induced Anemia by Time of Onset

Unconjugated bilirubin is water insoluble and travels through the bloodstream to the liver to be conjugated (water soluble) to be excreted through the GIT
During pregnancy, indirect bilirubin is transported across the placenta and conjugated by the maternal liver and safely excreted
After birth, the immature infant liver cannot efficiently metabolize bilirubin, causing unconjugated bilirubin to accumulate and resulting in neonatal jaundice
Unconjugated bilirubin can lead to kernicterus or permanent brain damage.

Postnatal Diagnosis

No single serologic test is diagnostic for ABO HDFN
The direct antiglobulin test (DAT) is the most important diagnostic test for ABO HDFN, which can be positive even in the absence of clinical anemia
The DAT is recommended to be done on all delivered infants, through a venipuncture to avoid contamination with maternal blood
ABO and RhD testing should be performed to assess the results

ABO HDFN

Group O individuals are most likely to form high-titer IgG anti-ABO antibodies, making ABO HDFN almost always limited to A or B infants of group O mothers with potent anti-A, B antibodies
Clinically significant ABO HDFN occurs most frequently in group O mothers with group A infants in white populations and group B infants in black populations.
ABO HDFN can occur in the first pregnancy and in any subsequent pregnancies due to it not relying on previous foreign RBC stimulation.
Tetanus toxoid administration and helminth parasite infection during pregnancy are linked to higher levels of IgG ABO antibodies and severe HDFN.
The typically mild course of ABO HDFN is related to the poor development of ABO antigens on fetal RBCs.
ABO antigens are not fully developed until after the first year of life, making group A infant RBCs serologically more similar to A2 adults, and making them less susceptible to ABO HDFN.

Fetal-Maternal Hemorrhage (FMH)

Maternal alloimmunization results from exposure to foreign red blood cells through previous or current pregnancy, previous transfusions, or organ transplant.
During pregnancy, there is spontaneous mixing between fetal and maternal circulation, which increases throughout pregnancy.
Any physical perturbation of a fetus or placenta in utero increases the risk of FMH, such as trauma, abortion, ectopic pregnancy, amniocentesis, or multiple pregnancies.
The ability of individuals to produce antibodies in response to antigenic exposure varies, and is influenced by complex genetic factors.

Antibody Identification

If antibody screening is reactive, the antibody identity must be determined.
Cold reactive IgM antibodies, such as anti-1, anti-IH, anti-Lea, anti-Leb, and anti-P, can be ignored.
Lewis system antibodies are common in pregnant women, but have not been reported to cause HDFN.
Anti-M and anti-N antibodies can be IgM, IgG, or a combination of both, and can cause mild to moderate HDFN.
The J-chain of IgM antibodies can be destroyed by treating the serum with a sulfhydryl reagent, while IgG antibodies will remain reactive.

Management of the Fetus

During pregnancy, women with known RBC alloimmunization and/or a history of HDFN are closely monitored using antibody titers.
The fetus is also closely monitored throughout pregnancy to check for fetal wellbeing and fetal anemia to determine the best time for delivery.
Fetal Ultrasound: Done at about 16 to 20 weeks' gestation, every 2 weeks, to track the degree of fetal anemia.
Invasive Monitoring:: Cordocentesis and Amniocentesis
Intrauterine Transfusion (IUT): Indications include MCA-PSV indicating anemia (>1.5 MoM), fetal hydrops noted on ultrasound examination, and additional matching for antigens such as c and E.
Rh Immune Globulin (RhIG)
The risk of an RhD-negative mother becoming allosensitized can be reduced by appropriate administration of RhIG.
The first dose is provided at 28 weeks' gestation or after trauma.
A second dose is given after delivery of an RhD-positive infant within 72 hours after delivery, and should be given even if more than 72 hours have elapsed.
RhIG is of no benefit once a person has formed anti-D.
RhIG is not indicated if the infant is found to be D-negative.
RhIG should be administered in cases of abortions, stillbirths, and ectopic pregnancies, as the blood type of the fetus cannot usually be determined.
The mother should be D-negative, and the infant should be D-positive or D-variant to administer RhIG.
Antibody titers are not recommended because the amount of circulating RhIG does not correlate with the effectiveness of the immune suppression or the amount of fetomaternal hemorrhage.
The half-life of IgG is about 25 days, so only about 10% of the antenatal dose will be present at 40 weeks gestation.
The anti-D from antenatal RhIG present at delivery should not be interpreted as active rather than passive immunization.
RhIG can be given IV or intramuscularly.
Intramuscular RhIG should only be given intramuscularly, as IV injections can cause severe anaphylactic reactions.
RhIG contains IgA and may be contraindicated in patients with anti-IgA and IgA deficiency who have had anaphylactic reactions to blood products.

Key Points

ABO HDFN is usually mild and can occur in any pregnancy.
Fetal anemia can be diagnosed using fetal ultrasound and Doppler measurements.
Intrauterine transfusions are used to treat severe fetal anemia.
RhIG is effective in preventing RhD sensitization in RhD-negative mothers.

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Description

This quiz covers the neonatal manifestations of hemolytic disease of the fetus and newborn (HDFN) induced anemia, focusing on the role of bilirubin and the consequences of its accumulation after birth. It also discusses postnatal diagnostic methods, including the direct antiglobulin test (DAT) and the importance of ABO and RhD blood group testing for newborns.