11.6: Transfusion II

Question 1

WHat is HDN?

Answer 1

“Hemolytic disease of the newborn”

- Hemolytic process in perinatal period resulting in abnormal RBC production

Question 2

What is the perinatal period?

Answer 2

The time during pregnancy

Question 3

Main cause of HDN?

Answer 3

• Unexpected alloantibodies
• These are not ABO antibodies
• Most are IgG and do not bind complement
• Associated with delayed, extravascular hemolysis

Question 4

What detects alloantibodies?

Answer 4

Antibody screen

Question 5

Why does HDN occur?

Answer 5

• Fetus inherits half of paternal RBC antigens
• Fetal RBC passes transplacentally into mother
• Mother produces IgG against fetal antigens that she does not share
• IgG can freely cross placenta

Question 6

Which antibodies freely cross into fetal circulation?

Answer 6

• IgG

Question 7

Normal progress in HDN?

Answer 7

• 1st pregnancy mother RH-, fetus RH+
• Pregnancy goes fine but mother now sensitized
• 2nd pregnancy, maternal antibodies cross placenta to attack RH + newborn

Question 8

What is an FMH?

Answer 8

“Fetal maternal hemorrhage”

• Incidence allowing fetal RBCs to cross placenta to mother
• Risk increases w/ gestational age: highest risk at pregnancy

Question 9

What is erythroblastosis fetalis?

Answer 9

• What happens to baby in HDN
• Peripheral smear of baby showed nucleated RBCs and erythroblasts
• Not normally found in marrow

Question 10

What are erythroblasts?

Answer 10

• RBC precursors

Question 11

What is another name for RH factor?

Answer 11

• Anti D
• D positive fetus’ mother makes anti D
• Fetus RBCs are thus sensitized and will agglutinate in antiglobulin test

Question 12

Where do fetus’s make RBCs>

Answer 12

• Liver and spleen
• Not in marrow until born
• Thus HDN babies demonstrate hepatosplenomegaly with liver failure

Question 13

Where are coag factors made?

Answer 13

• Liiver

- Baby with HDN cant form clots

Question 14

Symptoms of fetus with HDN?

Answer 14

• Hepatosplenomegaly
• Decreased coagulation and platelets
• Lowe liver function
• Shortened RBC life
• Hypoalbuminemia, leading to edema / hypotension and CHF
• Jaundice / hyperbilirubinemia
• High risk of kernicterus and neurologic damage

Question 15

What is anasarca?

Answer 15

• Whole body edema

Question 16

HDN IV or EV?

Answer 16

Extravascular

Question 17

What is kernicterus?

Answer 17

• Staining of basal ganglia due to severe hyperbilirubinemia
• Causes neuronal damage

Question 18

When does HDN occur with isoagglutinins?

THIS WILL BE ON EXAM*

Answer 18

• Normally when mother is “O” so has anti A/B/AB
• DAT will be positive
• Disease is usually milder

Question 19

What usually causes HDN?

Answer 19

• D antigen of RH blood group

- This is only type we have prophylaxis for

Question 20

How do we prophylaxis for HDN?

Answer 20

• Give mother protein concentrate of anti D: “RH immune globulin”
• This prevents mothers from making own alloantibodies
• Given at delivery and at 28 and 30 weeks
• We do not know how it works but it does

Question 21

What happens when mother is already sensitized and makes anti D?

Answer 21

• Pregnancy is high risk and taken care of specialists

Question 22

What is amniotic fluid made of?

Answer 22

• Fetal urine

Question 23

Old way of monitoring high risk sensitized mother?

Answer 23

• “Ultrasound guided amniocentesis”

- Sample amniotic fluid with needle and US

Question 24

New way of monitoring fetus for HDN?

Answer 24

• Ultra sound monitoring of cerebral blood flow for kinetics
• Anemic blood flows faster so we can test for anemia
• If anemia, intrauterine transfusion needed into umbilical vein while in placenta
• Monitor bilirubin once born

Question 25

How to treat baby with high bilirubin?

Answer 25

“Bili lights”

• Phototherapy with UV lights
• Solubilize unconjugated bilirubin
• Urobilinogen then excreted in kidneys
• **If lights don’t work exchange transfusion performed

Question 26

What is bilirubin?

Answer 26

• Yellow breakdown product of normal heme catabolism, caused by clearance of aged RBCs which contain hemoglobin
• Bilirubin is excreted in bile and urine
• Elevated levels may indicate certain disease

Question 27

What are cold and warm antibodies?

Answer 27

Cold: dont work at body temp so inconsequential
Warm: React at body temp
***Both are non specific and directed against RBC membrane antigens

Question 28

How do you dectect autoantibodies?

Answer 28

AIT: antibody screen

Question 29

Which autoantibodies cause most trouble?

Answer 29

• Warm, IgG in nature cant coat RBC or be in plasma

- Will cause positive DAT or IAT

Question 30

Characteristic of cold autoantibodies?

Answer 30

• Usually silent and don’t cause problems
• IgM
• Activate complement pathway

Question 31

Danger or warm autoantibodies?

Answer 31

• Cause cross matching compatibility with all RBCs

Question 32

Disease associated with unexpected autoantibodies?

Answer 32

1. Systemic Lupus Erythematosus
2. Chronic lymphocytic leukemia
   3, Normally idiopathic

Question 33

Markers of immune hemolysis?

Answer 33

1. Falling hemoglobin and hematocrit
2. Hyperbilirubinemia
3. Elevated LDL
4. Positive DAT /IAT
5. Low haptoglobin
6. Spherocytes

Question 34

Clinical findings in anemia?

Answer 34

• Fatigue
• Exercise intolerance
• Weakness
• Pallor

Question 35

Treatment of warm hemolytic anemia?

Answer 35

1. Corticosteroids
2. IV gammaglobulin
3. RBC transfusion: safe as long as on steroids
   - Even if cross math is incompatible

Question 36

Unique symptoms for cold agglutinin disease?1

Answer 36

1. Acrocyanosis when cold

Question 37

What is acrocyanosis?

Answer 37

• Bluish or purple coloring of the hands, lips and feet caused by slow circulation

Question 38

How to treat ptn. with cold agglutinin disease?

Answer 38

• Keep warm

- Prednisone

Question 39

Which hemolytic anemias associated with positive DAT?

Answer 39

• All

Question 40

Is Igm see on RBC in cold autoimmunity?

Answer 40

No only complement