7: Blood Groups, Blood Typing & Cross-Matching & transfusion

Question 0

How many different blood groups are there?

Answer 0

30 different blood group systems & 600+ antigens contained within these systems–>Many of these antigens are extremely rare

Question 1

What is a blood type (group)?

Answer 1

A classification of blood based on the presence (+) or absence (-) of inherited antigenic (antigens) substances on the surface of the RBCs.

-Antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system.

Question 2

What is the most important blood group systems in transfusion medicine ?

Answer 2

ABO and Rhesus (Rh)

Question 3

What is the ABO system?

Answer 3

• The genes for ABO are inherited in a Mendelian manner

- ABO system is SUGAR based, rather than protein based!

Question 4

What is the most common blood type? List the other types as well.

Answer 4

O+ = 37.4
A+= 35.7
B+= 8.5
O-= 6.6
A-= 6.3
AB+ 3.4
B- = 1.5
AB- = 0.6

Question 5

What is the Rhesus (Rh) System?

Answer 5

Group system is more complex than ABO & is the second most important blood group system in terms of transfusion medicine based of its high immunogenicity.

Question 6

How many Rh antigens are there?

Answer 6

Approx. 50 Rh antigens but only 5 are common

name D, C , c, E , and e

Question 7

What is Rh Positive and Rh Negative used for ?

Answer 7

Rh positive is used for individuals who are Rhesus (D) positive and Rh negative afro those who do not possess the Rhesus (D) antigen

Question 8

What is the Donor for O+?

Answer 8

O- and O+

Question 9

What were these blood groups named after? And what are they?

Answer 9

Named after the patients in whom the corresponding antibodies were initially encountered.

1) Kell (K)
2) Duffy (Fy)
3) Lewis

Question 10

What is Kell (K)?

Answer 10

Peptides that are highly immunogenic, but not as much as Rh; individuals are either K+ or K-

Question 11

What are Duffy (Fy) ?

Answer 11

The main antigens, Fya and Fyb; individuals can be either Fy (a+b), Fy (a-b+), Fy (a-b-)

Question 12

What are Lewis group systems?

Answer 12

2 types of Lewis antigens:

1) Lewis a and Lewis b;
2) individuals can be Lewis (a+b-)
3) Lewis (a+b+)
4) Lewis (a-b-)

Question 13

Today what components is donated blood separated into?

Answer 13

Processed to produce the separate different components that might be required for medical or surgical purposes;

1) Red cells
2) White cells
3) Platelets
4) Fresh frozen plasma
5) Heat treated plasma

Question 14

What is are examples of transfusion reactions ?

Answer 14

1) Hemolytic
2) Non-hemolytic
3) Allergic
4) Due to Volume Overload
5) Transfer of Bacteria

Question 15

Why can the Hemolytic reaction occur in transfusion reactions?

Answer 15

Due to an antigen-antibody reaction as a result of an incompatible transfusion, resulting in severe or fatal intravascular hemolysis

*****Concurrent w/ kidney failure!!

Question 16

Why can the Non-hemolytic reaction occur in transfusion reactions?

Answer 16

Die to damaged blood products that release high levels of cytokines, leading to fever and chills; usually benign

Question 17

Why can the Allergic reaction occur in transfusion reactions?

Answer 17

Lading to rashes and itching; usually benign

Question 18

What can result Due to Volume Overload occur in transfusion reactions?

Answer 18

Could cause pulmonary EDEMA; Outcome depends on other conditions

Question 19

What can the Transfer of Bacteria lead to in transfusion reactions?

Answer 19

Leads to Endotoxemia (as a result of free bacterial toxins) & Septicemia; potentially fatal

Question 20

What are the Test used in Transfusion Medicine?

Answer 20

1) Blood grouping
2) Antibody screen
3) Cross-Match

Question 21

Why were these tested used in transfusion?

Answer 21

To ensure that any blood transfused into a recipient is compatible w/ the donor & will not cause a transfusion reaction

Question 22

What is HDN? Why does it occur?

Answer 22

• Hemolytic disease of the newborn
• An important problem related to the Rh factor occurs in pregnant Rh- woman who are carrying Rh+ babies. Mother begins to produce anti-Rh agglutinins which often affects her second pregnancy. Her anti-Rh agglutinins may pass thru the placenta & agglutinate the fetal RBCs.

Question 23

What happens to the fetus in HDN?

Answer 23

***Agglutinated RBCs hemolyze, and the “2nd” baby is born with severe anemia.

• First baby results in the delivery of a health baby.
• Then after birth of if a miscarriage occurs, placental tearing exposes mother to Rh+ fetal blood that begins to make the anti-Rh agglutinins.

Question 24

How is HDN (Hemolytic disease of the newborn) prevented/treated?

Answer 24

Easier to prevent than to treat!

• If an Rh- woman gives birth to (or miscarries an Rh+ child she can be given an Rh immune globulin (sold under trade names like, **RhoGAM & Gamulin*
• The immune globulin binds fetal RBC agglutinogens so they cannot stimulate her immune system to produce anti-Rh agglutinins.

Question 25

What have physicians started giving for HDN complications?

Answer 25

They give Rh immune globulin throughout any pregnancy in which the MOTHER is Rh- and FATHER is Rh+

Question 26

What happens to woman immune system when Rh+ gets in her blood stream from fetus?

Answer 26

• Woman becomes sensitized antibodies form to fight Rh+ blood cells!
• In the next Rh+ pregnancy, antibodies attack fetal blood cells

Question 27

a) When one has the Rh factor what is their Rhesus blood type?
b) When one does not carry the Rh factor what is their Rhesus blood type?

Answer 27

a) Rh +

b) Rh-