Transfusion Medicine--Fung Flashcards
What is blood banking?
The collection, processing, storage and distribution of whole blood and apheresis.
Occurs at a blood collection facility or blood center
What is apheresis?
derived blood and blood components
What is transfusion medicine?
Pretransfusion and compatibility testing, post-manufacture processing
Occurs predominantly at a hospital
What is a blood group? How many are there?
blood group: “an inherited character of the red cell surface detected by a specific alloantibody”
339 recognized ones
Give some proteins, glycoproteins, and glycolipids that are found as antigens on the surface of RBCs.
ABO Rh (D) Secretor (Se, se) Lewis (Lea, Leb) Kell (K, k) Duffy (Fya, Fyb) Kidd (Jka, Jkb) I (I, i) MNS P
What are the basics of what you do when you type & cross match blood?
take a sample of blood
asking the Q: which antigens do these RBCs express?
add in test antibodies
watch for lattice formation & agglutination
What are the 3 phases of tube testing?
Immediate Spin
37dC phase: watch for agglutination at that temp
IAT phase
What do you usu find after the immediate spin?
usu find the IgM antibodies present in the blood. This is insignificant
What do you find in the IAT phase of tube testing?
at this phase you find RBCs coated with IgG or complement
these antibodies that are reactive are more likely significant
Describe DAT blood bank testing. Is this in vivo or vitro?
Direct Antiglobulin Test
in vivo: in the organism
tests whether the RBCs of the patient are sensitized to certain antibodies
**Wash away antibodies that are present.
**IgG antibodies added–see if they coat the RBCs
**AHG: antihuman globulin added to cause agglutination of RBCs bound to the IgG
Describe the IAT blood bank testing. Is this in vivo or vitro?
Indirect Antiglobulin Test
in vitro: on a slide
tests whether the serum of the pt has certain IgG antibodies
**Use fake RBCs
**Put them in patient serum
**Antibodies bind.
**AHG: antihuman globulin added to cause agglutination
What is the clinical significance of blood groups?
patients can get a hemolytic transfusion reaction
hemolytic disease of the newborn or fetus is also possible
Which are more significant antibodies: IgG or IgM?
IgG are more significant
warm reactive (37dC-temp of body)
require previous exposure
**IgM are naturally occurring & tend to be cold reactive
**ALso IGG can cross the placenta-significant for pregnancy
what are the Type I chains of the ABO blood system? Which gene modifies them?
glcyoproteins & glycolipids that are free floating in secretions & plasma
**found in saliva
Se gene modifies this to produce H antigen (substance)
What are the Type II chains of the ABO blood system? Which gene modifies them?
glycoprotein & glycolipids antigens that are bound to the RBC membrane
modified by H gene to produce H antigen (substance).
Further modified from there to A antigen or B antigen.
If the H antigen of Type II chains is not further modified…what is produced?
O antigen!
What determines a person’s genotype in terms of the ABO blood system?
3 codominant alleles on the long arm of chromosome 9
Aside from RBCs…where else are ABO antigens carried? Note: this is why it is important for organ transplants to be ABO compatible.
platelets endothelium kidney heart lung bowel pancreas
When do you first see ABO antigens on fetal RBCs? When do they reach adult levels?
First see: 6 weeks
Adult Levels: Age 4
Rank the following from most frequently seen to least frequently seen: A Blood AB Blood O Blood B Blood Note: this holds true across races
O most common
A
B
AB
Which ethnicity has 79% Type O blood?
native americans
What is Bombay type blood? How do you deal with transfusions?
Oh Lack of H, A, B antigens No H or Se genes can't be transfused! Need to do autotransfusions
Why are we worried about patients having antibodies against transfused blood antigen?
b/c it can activate complement
can get an immediate intravascular hemolytic transfusion reaction
When do you start to see ABO antibodies form in a person? When do they reach adult levels?
Start: 4 yo
Adult Levels: 10 yo
Type A blood person has which antibodies?
Anti-B antibodies IgM
react strongly at body temp
these are clinically significant
Type B blood person has which antibodies?
Anti-A IgM antibodies
react strongly at body temp
these are clinically signficant
Group O blood people have which antibodies?
Anti-A & Anti-B IgG antibodies
react best at body temp
**can see mild hemolytic disease of the newborn with these O moms.
Note: IgGs can cross the placenta!
What is forward typing? Use Type B blood person as an example.
use person’s blood & fake serum w/ antibodies.
Check for antigen.
Here: you see B antigen. Binds Anti-B antibodies.
What is reverse typing? Use Type A blood person as an example.
Use person’s serum & antibodies & use fake cells.
Which antibodies does this patient have?
Anti-B antibodies.
What do you use reverse & forward typing for?
use to see which ABO group a patient falls into…both need to agree for you to be good.
use immediate spin to check.
What are the 2 genes involved in the Rh system?
RHD (D/nothing)
RHCE (C/c, E/e)
Which of the antigens involved in the Rh System makes the most antibodies?
D makes the most!
very immunogenic 80% of D-neg makes anti-D
What type of hemolytic transfusion reaction is involved w/ the Rh system?
extravascular hemolysis
Which causes a more severe reaction?
anti-D & anti-c
OR
anti-C & anti-D & anti-e
anti-D & anti-c HDFN is more severe
Describe the type of hemolytic disease for fetus involved in the Rh system.
not first pregnancy
D-neg mom w/ D+ baby
use RhIG (commercially prepared anti-D) to treat
When do you use RhiG?
D-neg females at 28 weeks gestation
D-neg females s birth
D-neg females w/ pregnancy complications or invasive procedure (like amniocentesis)
What are the contraindications for using RhIG?
D-neg female who already has anti-D
D+ females
D-neg mom with D-neg baby
When we are dealing with D+ whole blood…what is the dosing for RhIG?
on full dose vial (300 micrograms) per 30 mL
When we are dealing with D+ RBCs…what is the dosing for RhIG?
one full dose vial (300 micrograms) per 15 mL
What are ways to determine percentage of fetal-maternal hemorrhage?
Fetal blood screen; qualitative
Kleihauer-Betke; quantitative but poorly reproducible
Flow cytometry; quantitative and more accurate
If you know a person’s weight…how do you determine blood volume?
Blood Volume = Weight (kg) X 70 mL/kg
If you don’t know a person’s weight…what should you assume their blood volume is?
5L=5000mL
If you know the KB value…how do you determine the amount of baby blood in the mom?
KB% X blood volume=baby blood in mom
So…know we have the value for D+ baby blood. How do we determine the amount of RhIG units to give?
Baby Blood in Mom/30mL (for whole blood)=Y.X
X5 round up 2 units
Mom is 70 kg. KB=2%. How much RhIG should be given?
Mom is D neg & baby is D+
BV=70kg X 70mL/kg=4900 mL 0.02 X 4900 = 98 mL D+ baby blood 98/30=3.2 Round up once. Give 4 units RhIG
What’s the deal with the LEwis system blood group?
consists of insignificant naturally occurring cold reacting igM antibodies
Secretors usu have which Lewis value?
Leb
Nonsecretors usu have which Lewis value?
Lea
What’s the deal with the MNS system blood group?
consists of IgM & IgG
Which antibodies to the MNS system are naturally occurring cold reacting IgM (insignificant)?
Anti-M & Anti-N
Which antibodies to the MNS system are significant, exposure requiring warm reacting IgG?
Anti-S
Anti-s
Anti-U
Which antibody that is a part of the MNS system could cause severe HDFN (dangerous for fetus!)?
Anti-M
What’s the deal with the I system?
antigens are built on 2 types of chains simple chains (i) found in neonates branched chains (I) found in adults insignificant naturally occurring cold reacting IgM auto-antibody
What happens with auto-anti-I?
cold agglutinin disease
mycoplasma pneumonia infections