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Blood transfusion science > HDFN > Flashcards

HDFN Flashcards

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1
Q

what is the other name for HDFN

A

Erythroblastosis fetalis

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2
Q

define HDFN

A

Is a disorder of the fetus or new born in which fetal red blood cells are destroyed by martenal IgG antibodies

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2
Q

What role do antibodies directed against fetal antigens play in fetal red cell survival?

A

These antibodies cross the placenta, sensitize fetal red cells, and shorten red cell surviva

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3
Q

How do these antibodies affect fetal red cells once they cross the placenta?

A

The antibodies sensitize fetal red cells, leading to their premature destruction.

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3
Q

What is the range of disease severity caused by the premature destruction of fetal red cells?

A

The disease severity can vary from mild anemia to death in utero.

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4
Q

What are some possible outcomes of the disease caused by the sensitization and destruction of fetal red cells

A

Possible outcomes include mild anemia or death in utero due to the premature destruction of fetal red cells.

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4
Q

What functions does the placenta serve during pregnancy?

A

The placenta functions as the site of oxygen, nutrient, and waste exchange, and serves as a barrier between maternal and fetal circulations.

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5
Q

How does the placenta protect against antibody production during pregnancy

A

The placenta limits the number of fetal red cells entering the maternal circulation, thereby reducing the chances of antibody production.

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5
Q

How does ABO incompatibility between mother and child provide additional protection against immunization?

A

Intravascular hemolysis of ABO-incompatible fetal red cells by maternal anti-A or anti-B reduces exposure to fetal cells carrying foreign antigens.

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6
Q

What happens at the time of delivery regarding fetal red cells and maternal circulation?

A

When the placenta is separated from the uterus, a significant number of fetal red cells escape into the maternal circulation, known as fetomaternal hemorrhage (FMH).

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7
Q

What other events can cause immunization from fetal red cell exposure besides delivery?

A

Immunization can result from fetal red cell exposure after amniocentesis, spontaneous or induced abortion, cordocentesis, ectopic pregnancy, or abdominal trauma.

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8
Q

How can fetal red cells carrying different antigens stimulate an immune response in the mother?

A

Fetal red cells carrying paternal antigens can stimulate an active immune response in the mother, resulting in the production of IgG antibodies.

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9
Q

What is fetomaternal hemorrhage (FMH), and when does it occur?

A

Fetomaternal hemorrhage (FMH) occurs when a significant number of fetal red cells escape into the maternal circulation, typically at the time of delivery when the placenta is separated from the uterus.

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10
Q

What triggers an active immune response in the mother towards fetal red cells?

A

Fetal red cells carrying paternal antigens, which are different from the mother’s antigens, can stimulate an active immune response in the mother, leading to the production of IgG antibodies.

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10
Q

List some events other than delivery that can cause fetal red cell exposure and potential immunization in the mother

A
  1. amniocentesis
  2. spontaneous or induced abortion
  3. cordocentesis
  4. ectopic pregnancy,
    5.abdominal trauma
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11
Q

what is hydrops fetalis

A

edema in the fetus

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12
Q

How do IgG antibodies cross the placental barrier in a subsequent pregnancy?

A

IgG antibodies cross the placental barrier by an active transport mechanism.

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12
Q

What happens to the fetal red cells when IgG antibodies bind to fetal antigens?

A

The fetal red cells are destroyed by macrophages in the fetal liver and spleen.

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13
Q

What happens to hemoglobin released from damaged fetal red cells?

A

Hemoglobin is metabolized to indirect bilirubin, which is then transported across the placenta, conjugated by the maternal liver, and harmlessly excreted by the mother.

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14
Q

What is the result of continued red cell destruction in the fetus?

A

The fetus becomes increasingly anemic.

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14
Q

How does the fetus compensate for the destruction of red cells?

A

The fetal liver and spleen enlarge as erythropoiesis increases to compensate for red cell destruction.

15
Q

What are erythroblasts, and why are they released into the fetal circulation?

A

Erythroblasts are immature red cells, and they are released into the fetal circulation as a response to increased erythropoiesis, a condition known as erythroblastosis fetalis.

16
Q

What are the potential consequences if erythroblastosis fetalis is left untreated?

A

Untreated erythroblastosis fetalis can lead to cardiac failure and hydrops fetalis, which includes edema and fluid accumulation in the fetal peritoneal and pleural cavities.

17
Q

What happens to the infant after delivery regarding red cell destruction?

A

After delivery, red cell destruction continues, leading to the release of indirect bilirubin

17
Q

What is the greatest threat to the fetus in cases of erythroblastosis fetalis?

A

The greatest threat to the fetus is cardiac failure resulting from uncompensated anemia.

18
Q

How is indirect bilirubin managed in utero versus after birth?

A

In utero, indirect bilirubin is conjugated in the maternal liver and excreted. After birth, the newborn liver is deficient in glucuronyl transferase, which is needed to conjugate indirect bilirubin.

18
Q

What role does albumin play in the circulation of indirect bilirubin in newborns?

A

Indirect bilirubin binds to albumin and circulates harmlessly in the newborn

19
Q

What happens when the binding capacity of albumin is exceeded by indirect bilirubin?

A

When the binding capacity of albumin is exceeded, indirect bilirubin binds to tissues, leading to jaundice.

20
Q

What specific risk does indirect bilirubin pose to the central nervous system (CNS)?

A

Indirect bilirubin can bind with tissues of the CNS, causing permanent brain damage known as kernicterus.

21
Q

What are the potential consequences of kernicterus in newborns

A

Kernicterus can result in deafness, mental retardation, or death.

21
Q

what is kernicterus

A

is a type of brain damage that occurs in newborns due to extremely high levels of bilirubin in the blood. Bilirubin is a waste product produced when the liver breaks down old red blood cells1. When bilirubin levels become too high, it can accumulate in the brain, leading to neurological damage

22
Q

mention 3 factors that must be fulfilled for HDFN to occur

A
  1. The red cell antibody produced by the mother must be of the IgG class. IgG is the only immunoglobulin capable of crossing the placental barrier. This active transport across the placenta is determined by the fragment, crystallizable, or Fc, portion of the immunoglobulin molecule. IgM antibodies such as anti-Lea, anti-Leb, anti-M, anti-N, and anti-P1 have not been implicated in HDFN.
  2. The fetus must possess an antigen that is lacking in the mother. The gene for the antigen is inherited from the father. If the father is known to be homozygous for the gene, 100% of the children inherit the gene and are at risk for HDFN. If the father is known to be heterozygous, only 50% of the children may inherit the gene and are at risk.
  3. The antigen must be well developed at birth. Blood group antigens such as Lewis, P1, and I are not well developed at birth. Antibodies to these antigens are not expected to cause HDFN because the antigen is not available to bind with the maternal antibody.
23
Q

Based on antibody specificity mentions three categories/classes of HDFN

A
  1. D/Rh
  2. ABO
  3. Other antibodies
23
Q

What is the most severe cause of Hemolytic Disease of the Fetus and Newborn (HDFN)?

A

Anti-D is responsible for the most severe cases of HDFN.

24
Q

When do D-negative women typically become sensitized to D-positive fetal red cells

A

D-negative women typically become sensitized at delivery during their first pregnancy with a D-positive baby.

25
Q

Do first pregnancies often show clinical signs of HDFN?

A

The first pregnancy rarely demonstrates clinical signs of HDFN.

26
Q

What happens after the production of anti-D in subsequent pregnancies with D-positive fetuses?

A

Subsequent D-positive fetuses are affected to varying degrees by the maternal anti-D.

27
Q

What test result indicates that maternal anti-D has bound to fetal D-positive red cells?

A

A positive direct antiglobulin test (DAT) indicates that maternal anti-D has bound to fetal D-positive red cells.

28
Q

What are the symptoms of moderately affected infants?

A

Moderately affected infants develop signs of jaundice and corresponding elevations in bilirubin levels during the first few days of life.

29
Q

What are the symptoms of severely affected D-positive infants?

A

Severely affected D-positive infants experience rapid red cell destruction, anemia in utero, and jaundice within hours of delivery.

29
Q

What medical intervention might be necessary for severely affected infants to prevent kernicterus?

A

Exchange transfusion may be necessary to reduce bilirubin levels and prevent kernicterus after delivery.

30
Q

what commercially available human sourse is used to prevent alloimmunization to the D antigen

A

Rh immune globulin

31
Q

How often does HDFN caused by ABO incompatibility occur?

A

HDFN caused by ABO incompatibility occurs in 1 in 150 births.

31
Q

What are the usual clinical signs of HDFN caused by ABO incompatibility in infants

A

Most cases are subclinical and do not necessitate treatment. Some infants may experience mildly elevated bilirubin levels and some degree of jaundice within the first few days of life.

32
Q

What is the common treatment for infants with HDFN caused by ABO incompatibility?

A

These cases can usually be treated with phototherapy.

32
Q

What are some possible explanations for mild red cell destruction despite high levels of maternal antibody?

A

Presence of A or B substances in the fetal tissues and secretions that bind or neutralize ABO antibodies, poor development of ABO antigens on fetal or infant red cells, and reduced number of A and B antigen sites on fetal or infant red cells.

33
Q

Why are group O individuals more likely to cause ABO HDFN?

A

Group O individuals are more likely to have higher titers of IgG ABO antibodies compared with other ABO groups.

33
Q

In which group of babies does ABO HDFN occur most frequently?

A

ABO HDFN occurs most frequently in group A or B babies born to group O mothers.

34
Q

How does ABO incompatibility often affect pregnancies differently than anti-D incompatibility

A

ABO incompatibility often affects the first pregnancy because of the presence of naturally occurring ABO antibodies, whereas anti-D incompatibility typically sensitizes D-negative women at delivery in the first pregnancy with a D-positive baby.

35
Q

What are the differences in clinical and laboratory findings between HDFN caused by ABO incompatibilities and anti-D?

A

The clinical and laboratory findings in HDFN caused by ABO incompatibilities and anti-D are compared but are not specified in the provided text.

35
Q

when is ABO HDFN most common

A

Most common in type A or B babies born to type O mothers

Blood transfusion science (17 decks)

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