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22 - Immunohematology
Pre-Transfusion Tests
Genetic Control of the ABO Blood Group Antigens
GENES PRESENT TRANSFERASE PRODUCED TERMINAL SUGAR RBC PHENOTYPE
HH or Hh Fucosyltransferase Fucose O
HH or Hh and A Fucosyltransferase, N-
acetylgalactosaminyltransferase
Fucose, N-acetylgalactosamine A
HH or Hh and B Fucosyltransferase, D-galactosyltransferase Fucose, galactose B
HH or Hh and A plus B Fucosyltransferase, N-
acetylgalactosaminyltransferase
D-galactosyltransferase
Fucose, N-
acetylgalactosamine, D-
galactose
AB
hh, or hh and any other
gene (A and/or B)
None, or N-acetylgalactosaminyltransferase and/or
D-galactosyltransferase
None Bombay
Gal added to the subterminal Gal confers B activity; GalNAc
added to theh subterminal Gal confers A activity to the sugar.
Unless the fucose moiety that determines H activity is attached
to the number 2 carbon, galactose does not accept either sugar
on the number 3 carbon.
Applications of Blood Group Serology
Blood grouping of donors and patients
Provision of blood for patients
Exclusion of paternity
Criminal investigations
Recipients Red Cells Plus
ABO Group Anti-A Anti-B Anti-AB
A ++++ - ++++
B - ++++ ++++
AB ++++ ++++ ++++
Subgroups A or B - - ++
PATIENTS SERUM plusABO GROUP A RBCs B RBCs
A - ++++
B ++++ -
AB - -
O ++++ ++++
Recipients ABO
Blood Group
Acceptable ABO
Blood Group of
Donor Red Cells
Acceptable ABO
Blood Group of
Donor Plasma
A A,O A, AB
B B,O B, AB
AB AB,A,B,O ABO O O, A, B, AB
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Antibody Screen
Same procedure as the crossmatch but substituting
Group O red cells phenotyped for multiple antigens
INTERPRETATION OF COMPATIBILITY TESTS
Agglutination Cause of
Agglutination
Compatible
for
Transfusion
Antibody
Screen
Crossmatch
+ - Antibody screen
with antigen on
screening cells
but not on donor
cells
Possibly
(phenotyped
donor to
confirm
compatibiltiy)
- + Antibody reacts
with a low
incidence antigen
Donor cells have a
positive DAT
Technical error -
repeat
+ + Antibody reacts
with an antigen
on donor cells
and screening
cells
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Coombs/Antiglobulin Test
DAT Use
Diagnosis of:
Hemolytic disease of newborn
Autoimmune hemolytic anemia
Drug-induced hemolytic anemia
Transfusion reactions
IAT Use
Antibody screening
Phenotyping
Cross-matching
Blood Components
Blood: 6% -8% of body weight
Plasma
Components Relative
Amounts
Function
Plasma Portion (50%-60% of total volume):1.Water 91% - 92%
of plasma
volume
Solvent
2.
Plasma proteins
(albumin, globulins,
fibrinogen, etc.)
7% - 8% Defense, clotting,
lipid transport, roles
in ECF volume, etc.
3.Ions, sugars, lipids,
amino acids,
hormones, vitamins,
dissolved gases
1% - 2% Roles in ECF
volume, pH, etc.
Cellular Portion(40% - 50% of total volume):
1.Red blood cells 4,800,000 -
5,400,000
per milliliter
Oxygen, carbon
dioxide transport
2.White blood cells:
Neutrophils
Lymphocytes
Monocytes
(macrophages)
Eosinophils
Basophils
3,000 -
6,750
1,000 -
2,700
150 - 720
100 - 360
25 - 90
Phagocytosis
Immunity
Phagocytosis
Roles in
inflammatory
response, immunity
Roles in
inflammatory
response, immunity
3.
Platelets 250,000 -
300,000
Roles in clotting
Principle 1:
The cause of the deficiency should be identified.
Principle 2:
Only the deficient component should be replaced.
Blood Components
Oxygen Carrying Components
Red cell concentrates
Leukocyte-poor blood Frozen-thawed red cells
Platelet Products
Platelet rich plasma (PRP)
Platelet concentrates (PC)
Plasma Products
Fresh frozen plasma (FFP)
Frozen plasma (FP)
Cryoprecipitate
Stored plasma
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Principle 3:
The blood product should be as safe as possible.
Blood Constituent Type of Transfusion Reaction
Red cells Acute hemolytic transfusion reaction
Delayed transfusion reaction
Transfusion of red cell alloantibodies
(passive alloimmunization)
Alloimmunization
White cells Febrile transfusion reaction
Leuokagglutinin-associated pulmonary
edema
Alloimmunization
Platelets Alloimmunization
Post transfusion purpura
Leukopenia
Plasma proteins Urticaria
Anaphylaxis
Other Graft-versus-host disease (GVHD)
Whole Blood (WB)
Composition: RBCs (approx. Hct 40%); WBCs;
platelets; plasma
Volume: 500 mL
Use: Increase both red cell mass and plasma volume
(WBCs and platelets not functional; plasma deficient
in labile clotting Factors V and VIII) Storage Temperature: 1-6C
Shelf Life: CPDA-1 = 35 days
Quality Control:
1. Donor Hemoglobin 12.5 g/dL
2. Volume = 450 mL + 10%
Clinical Indications:
WB 1. Active bleeding with at least one of the following:
a. Loss of over 15% blood volume
b. Hgb less than 9 g/dL
c. Blood pressure decrease over 20 mm Hg
and/or less than 90 mm Hg systolicWB 2. Pre-operative patients with expected blood loss
of more than 25% blood volume
Packed Red Blood Cells (PRBC)
Composition: RBCs (approx. Hct 75%); reduced
plasma; WBCs and platelets
Volume: 250 mL
Use: Increase red cell mass in symptomatic anemia
(WBCs and platelets not functional)
Storage Temperature: 1-6C
Shelf life:
1. CPDA 1 (close system) = 35 days
2. CPDA 1 (open system) = 24 hours
Quality Control:
1. Volume of red cells (4 per month) > 170 mL
2.
Hct (4 per month)< 70%(mean); never > 80%
Clinical Indications:
R 1 Hgb less than 8 gm/dL or Hct less than 24% (if not due
to treatable cause)
R 2 Pre-operative patients with:
a. Hgb less than 8 g/dL or Hct less than 24%
b. Major bloodletting operation and Hgb less
than 10/dL or Hct less than 30%
c. Signs of inadequate oxygen-carrying
capacity (symptomatic anemia)
R 3 Symptomatic anemia regardless of Hgb level
(dyspnea, syncope, postural hypotension,tachycardia, chest pains, TIA)
R 4 Hgb less than 10 g/dL or Hct less than 30% in patients
with COPD, CAD, hemoglobinopathy, sepsis, aortic
stenosis and cerebral infarct
R 5 Blood loss of less than 10% blood volume
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Washed Red Blood Cells
Composition: RBCs(approx. Hct 75%);
< 5 x 108 WBCs; no plasma
Volume: 180 mL
Use: Increase red cell mass; reduce risk of allergic
reactions to plasma proteins
Storage Temperature: 1-6C Shelf life: 24 hours
Quality Control: same as PRBC (prior to washing)
Clinical Indications:
WP 1 History of previous severe allergic transfusion
reactions or anaphylactoid reaction in
immunocompromised patients
WP 2 Transfusion of group O blood during emergencies
when the specific blood is not immediately available
WP 3 Paroxysmal nocturnal hemoglobinuria
Leuko-Reduced RBCs(LR-RBCs)
Prepared by filtration
Composition: > 85% original volume of RBC;
< 5 X 106WBCs; few platelets; minimal plasma
Volume: 225 ml
Uses: Increase red cell mass; 5.5 X 1010
/unit); RBCs; WBCs;
plasma
Volume: 50 mL
Use: Stop bleeding due to thrombocytopenia or
thrombocytopathy
Storage Temperature: 20 - 24C Shelf life:
1. CPDA- 1 (close system) = 5 days
2. CPDA-1 (open system) = 24 hours
Quality Control:
1. pH (4 per month) = never < 6.0
2. Platelet count (4 per month) = 5.5 X 1010
(75% or more)
3. Plasma volume (4 per month) = 45 65 mL
Clinical Indications:
P-1 Prophylactic administration with count 20,000 and
not due to TTP, ITP, HUS
P-2 Active bleeding with count 50,000
P-3 Platelet count 50,000 and patient to undergo
invasive procedure within 8 hours
P-4 Platelet count 100,000 if surgery in on critical area
(e.g. eye, brain, etc.)
P-5 Massive transfusion with diffuse microvascular
bleeding and no time to obtain platelet count
Leuko-Reduced Platelets (LRPs) Prepared by Filtration
Composition: Platelets (>5.5 X 1010
/unit); RBCs;
WBCs < 5 x 106WBCs; plasma
Volume: 50 ml Uses: Same as Platelets; 3 X 1011
/unit); RBCs; WBCs; plasma
Volume: 300 ml
Uses: Same as Platelets; sometimes HLA- matched
Storage Temperature: 20-24
Shelf life: 1. CPDA-1 (close system) = 5 days
Quality Control:1. pH (4/month) = not < 6.0
2. Platelet count (4/month) = 3 X 1011
(mean)
Clinical Indications:Same as PC
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Fresh Frozen Plasma (FFP)
Composition: Plasma with all coagulation factors
Volume: 200-250 ml
Uses:
1. Provide all coagulation factors in deficiency
states
2. Plasma expander
Storage Temperature: (-) 30C or lower
Shelf life: 12 months
Quality Control: Volume (every unit) = 235 ml (mean)
Clinical Indications:
F-1 PT or PTT > 1.5 times mid-normal range within 8
hours of transfusion (PT > 17 sec., PTT > 47 sec)
F-2 Specific factor deficiencies not treatable with
cryoprecipitate
F-3 Reversal of coumadin anticoagulant in patients who
are bleeding and not treatable with vitamin K
F-4 Treatment of TTP
F-5 Patient undergoing an invasive procedure with PT of
less than 70% and /or PTT of more than 44 seconds
F-6 Clinical coagulopathy associated with:
Massive transfusion ( 10 units of blood in
24 hours)
Late pregnancy termination or abruptio
placentae
Cryoprecipitate (CP)
Composition: Plasma with Fibrinogen; Factors VIII and
XIII; von Willebrand Factor
Volume: 15-20 ml
Uses:
1. Provide fibrinogen, Factors VIII and XIII and
Willebrand Factor in deficiency states, e.g.
Hemophilia A, Willebrands Disease
2. Topical Fibrin glue
Storage Temperature: (-) 30C or lower
Shelf life: 12 months
Quality Control: Factor VIII (4/month) = 80 IU (mean)
Clinical Indications:
C-1 Significant hypofibrinogenemia (100 mg/dL)
C-2 Hemophilia A
C-3 Von Willebrands disease or uremic bleeding with
prolonged bleeding time
Recommendations
RBC Products
Transfusion of blood products on a unit-to-
unit basis is encouraged
A thorough clinical re-evaluation should be
made before the next transfusion
A representative post-transfusion
Hemoglobin and Hematocrit determination
could be made at least after 24 hours
Platelet Concentrate
A representative post-transfusion platelet
count could be made at least after one(1)
hour.
Cryoprecipitate and fresh frozen plasma
A more accurate post-transfusion PT and/or
PTT could be done at least after four (4)
hours.