Transfusion Medicine II

Question 1

Hemolytic Disease of the Newborn

Answer 1

A hemolytic process in the perinatal period, resulting in abnormal RBC destruction with multiple causes:
-􏰀 Alloimmunization to RBC antigens
􏰀- Congenital RBC defects (membranes, enzymes, etc.)
􏰀- Acquired RBC defects usually secondary to infection

Question 2

How does alloimmunization of an Rh- woman in pregnancy occur?

Answer 2

1. Mother is exposed to the Rh+ Ag on the fetus

2. Mother is sensitized and will make IgG VS the fetus

Question 3

When is the greatest risk for D-alloimmunization occur?

Answer 3

At delivery

Question 4

What can be seen in the smear of an infant with HDN?

Answer 4

Erythroblastosis fetalis - RBC precursors are seen in the blood which is an abnormal sign

Question 5

What is the DAT test on a newborn with HDN?

Answer 5

It will be positive

Question 6

Why is there hepatosplenomegaly in HDN?

Answer 6

Most fetal hematopoiesis occurs in liver and spleen

so it causes hepatosplenomegaly

Question 7

What are some other signs of HDN?

Answer 7

Jaundice - hyperbilirubinemia due to lysis of RBCs
Ansarca
Hypoalbuminemia

Question 8

Kernicterus

Answer 8

Kernicterus is the staining of the basal ganglia due to severe hyperbilirubinemia which results in neural damage

Question 9

What is ABO HDN?

Answer 9

Almost exclusive to Group O mothers as they make anti-A, anti-B and anti-A,B that could be IgG in nature which can cross the placenta and sensitize the RBCs.

Question 10

What is the DAT result for ABO HDN?

Answer 10

The DAT will be positive due to IgG attached to RBCs in vivo

Question 11

How is HDN prevented?

Answer 11

Protein concentrate of “Anti-D”, prepared from pools of serum from previously-sensitized females is injected IV or IM.

Question 12

How are SENSITIZED pregnancies to Rh managed - that is, alloantibodies already have been formed?

Answer 12

• Early delivery
• Noninvasive fetal blood flow monitoring - MCA flow velocity
• Exchange transfusion - remove sensitized RBCs

Question 13

What are unexpected autoantibodies and what are they detected by?

Answer 13

Directed against generic RBC membrane antigens and they are detected by the IAT.

Question 14

What is the action of most unexpected autoantibodies?

Answer 14

Most are clinically silent. Only some cause hemolysis.

Question 15

What are warm auto-Ab?

Answer 15

The “Warm” ones are usually IgG in nature, can coat the patient’s RBSs and / or be in the patient’s plasma
• Can cause a positive DAT and / or IAT
• They function at 37 ˚C

Question 16

What are cold auto-Ab?

Answer 16

The “Cold” ones are often IgM in nature and can activate
complement
• They function at less than 25 ˚C

Question 17

What is the result of Warm auto-Ab on the crossmatch test?

Answer 17

Warm autoantibodies in plasma cause XM-incompatibility against ALL RBC units!!!

Question 18

What are some of the major causes of autoantibodies?

Answer 18

• Systemic lupus erythematosis

- Chronic lymphocytic leukemia

Question 19

What are some lab markers of autoimmune hemolysis?

Answer 19

• Falling hemoglobin (Hgb) and hematocrit (Hct)
• Hyperbilirubinemia
• Elevated total LDH

Question 20

Warm Autoimmune Hemolytic Anemias

Answer 20

􏰀- Pathogenic IgG autoantibody coats RBCs (positive DAT) 􏰀 - Extravascular clearance of RBCs - splenic

Question 21

What is the main treatment of Warm Autoimmune Hemolytic Anemias?

Answer 21

• Corticosteroids

Question 22

Cold Agglutinin Disease

Answer 22

-􏰀 Moderately severe anemia, symptoms related to degree
of anemia
􏰀- Acrocyanosis, precipitated by exposure to cold

Question 23

What is the main population of cold agglutinin disease?

Answer 23

Children

Question 24

What are the lab findings of cold agglutinin disease?

Answer 24

• 􏰀Cold refers to Ag-Ab reactions taking place at 25˚C or colder temperatures
  􏰀- Positive DAT due to anti-complement only 􏰀
• Cold agglutinin detectable in plasma and on RBCs

Question 25

What are the main treatments of cold agglutinin disease?

Answer 25

Keep the patient warm

Question 26

Drug-induced Hemolytic Anemias

Answer 26

Drug exposure binding to RBC leads to formation of auto-Ab