7: Blood Groups, Blood Typing & Cross-Matching & transfusion Flashcards
How many different blood groups are there?
30 different blood group systems & 600+ antigens contained within these systems–>Many of these antigens are extremely rare
What is a blood type (group)?
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.
What is the most important blood group systems in transfusion medicine ?
ABO and Rhesus (Rh)
What is the ABO system?
- The genes for ABO are inherited in a Mendelian manner
- ABO system is SUGAR based, rather than protein based!
What is the most common blood type? List the other types as well.
O+ = 37.4 A+= 35.7 B+= 8.5 O-= 6.6 A-= 6.3 AB+ 3.4 B- = 1.5 AB- = 0.6
What is the Rhesus (Rh) System?
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.
How many Rh antigens are there?
Approx. 50 Rh antigens but only 5 are common
name D, C , c, E , and e
What is Rh Positive and Rh Negative used for ?
Rh positive is used for individuals who are Rhesus (D) positive and Rh negative afro those who do not possess the Rhesus (D) antigen
What is the Donor for O+?
O- and O+
What were these blood groups named after? And what are they?
Named after the patients in whom the corresponding antibodies were initially encountered.
1) Kell (K)
2) Duffy (Fy)
3) Lewis
What is Kell (K)?
Peptides that are highly immunogenic, but not as much as Rh; individuals are either K+ or K-
What are Duffy (Fy) ?
The main antigens, Fya and Fyb; individuals can be either Fy (a+b), Fy (a-b+), Fy (a-b-)
What are Lewis group systems?
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-)
Today what components is donated blood separated into?
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
What is are examples of transfusion reactions ?
1) Hemolytic
2) Non-hemolytic
3) Allergic
4) Due to Volume Overload
5) Transfer of Bacteria
Why can the Hemolytic reaction occur in transfusion reactions?
Due to an antigen-antibody reaction as a result of an incompatible transfusion, resulting in severe or fatal intravascular hemolysis
*****Concurrent w/ kidney failure!!
Why can the Non-hemolytic reaction occur in transfusion reactions?
Die to damaged blood products that release high levels of cytokines, leading to fever and chills; usually benign
Why can the Allergic reaction occur in transfusion reactions?
Lading to rashes and itching; usually benign
What can result Due to Volume Overload occur in transfusion reactions?
Could cause pulmonary EDEMA; Outcome depends on other conditions
What can the Transfer of Bacteria lead to in transfusion reactions?
Leads to Endotoxemia (as a result of free bacterial toxins) & Septicemia; potentially fatal
What are the Test used in Transfusion Medicine?
1) Blood grouping
2) Antibody screen
3) Cross-Match
Why were these tested used in transfusion?
To ensure that any blood transfused into a recipient is compatible w/ the donor & will not cause a transfusion reaction
What is HDN? Why does it occur?
- 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.
What happens to the fetus in HDN?
***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.
How is HDN (Hemolytic disease of the newborn) prevented/treated?
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.
What have physicians started giving for HDN complications?
They give Rh immune globulin throughout any pregnancy in which the MOTHER is Rh- and FATHER is Rh+
What happens to woman immune system when Rh+ gets in her blood stream from fetus?
- Woman becomes sensitized antibodies form to fight Rh+ blood cells!
- In the next Rh+ pregnancy, antibodies attack fetal blood cells
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?
a) Rh +
b) Rh-
