1 Flashcards
Why is it necessary to wash red cell with NSS for three times?
To remove serum/plasma which may contain proteins that may affect the results. Also, through washing, it removes fibrinogen to avoid clots.
Why is a Pasteur pipette used in delivering 0.1 ml of washed packed red blood cells instead of a serological pipette?
Pasteur pipette was used to avoid clogging if pipette used has a small bore and will affect the fixed volume.
What is the important of preparing a red cell suspension in the laboratory?
Red cell suspensions provide the appropriate serum to cell ratio to allow for grading and interpretation of tests results.
Amount of washed RBC formula
Total volume x desired %
Total volume
prbc/desired %
Desired %
prbc/TV x 100
NSS
TV-prbc
Differentiate agglutination from hemolysis
Hemolysis is the lysis of RBC w/ liberation of Hemoglobin while agglutination, RBC bound to Ab that forms a latticework through Ag Ab bridges.
Why is it necessary to observe agglutination reactions microscopically?
Because it is the gold standard for sero-diagnosis of leptospirosis because of its unsurpassed diagnostic specificity
What is rouleaux formation? What causes it? How do we resolve this problem?
Rouleaux formation is formed by RBC stacked like coins. The appearance of rouleaux may be artificially caused by a poor preparation of the smear or by viewing the slide in a thickened area. When rouleaux formation is truly present, it is caused by an increase in cathodal proteins, such as immunoglobulins and fibrinogen.
Blood Type A
Antigen: A; Antibodies: B; Can receive: O, A; Can Give to: A, AB
Blood Type B
Antigen: B; Antibodies: A; Can receive: O, B; Can give blood to: B, AB
Blood Type AB
Antigen: A and B; Antibodies: None; Can Receive: O, A, B, AB; Can Give to: AB
Blood Type O
Antigen: None; Antibodies: A and B; Can receive: O; Can Give Blood to: O, A, B, AB
Interpretation of Forward Blood Grouping:
A= + 0 + 0 B= 0 + + 0 AB= + + + 0 O = 0 0 0 0
Interpretation of Backward Blood Grouping:
A = 0 + + 0 B= + 0 + 0 AB = 0 0 0 0 O= + + + 0
What is an antiserum?
An antiserum is a reagent source of ABb that is commercially available.
What kind of antigen will anti-A detect? Anti-B?
Anti- A can detect the antigen while Anti- B can detect the B- antigen present in the blood sample.
When is blood typing ordered?
ABO groupings and Rh typing are performed on all donated blood. It is also performed when people require blood transfusion.
It is done also on pregnant women to determine compatibility with developing fetus.
For patients who will undergo a transplant.
Common causes of false results in ABO Testing
False Negative:
- Reagent no added
- Hemolysis
- Undercentrifugation
- Incubation above 20-24 degrees
False Postive:
- Overcentrifugation
- Dirty glassware
- Contaminated reagents
What is Rh typing?
Used to determine whether you have a specific protein called Rh factor on the outer layer of the RBC.
What are the other names of ABO Reverse Typing?
Also known as backward typing, indirect typing and serum typing
What is the importance of doing serum typing?
Serum typing utilizes centrifugation which enhances the reaction of possibly weak Ag/Ab so it can be properly detected.
What kind of antibody is found in group “a”? group “B”? group “AB”?
Group A has the B antibody
Group B has the A antibody
Group AB has no antibody present
What is the difference between ABO Forward Typing from ABO Reverse Typing?
ABO forward typing utilizes whole blood and detects Ag from sample blood by using commercially available antisera. ABO reverse typing utilizes only one serum of the patient and detects antibodies present in the serum sample.
Interpretation of H secretor
A= + B= 0; Ag present: B,H; Status: B,H secretor A= 0 B= +; Ag present: A, H; Status: A, H A= 0 B= 0; Ag present: A,B,H; Status A,B,H A= + B= +; Ag present: None/H; Status: H secretor
What is meant by secretor?
A secretor is an individual who is capable of secreting soluble, glycoprotein ABa-soluble substances into saliva and other body fluids.
Why must saliva be subjected into increased temperature using a water bath prior to its use?
Saliva is subjected to increased temp in order to inactivate or denature the enzymes present
What is the principle involved in this test?
ABH antigens are present in a soluble form n a liquid, they will neutralize their corresponding antibodies and the antibodies will no longer be able to agglutinate red cells possessing the same antigens
What is the purpose of diluting the saliva in this test?
Saliva is diluted to prevent zonal secretion during the test
Why is saliva preferred as specimen for the determination of blood group soluble substances?
Saliva is the preferred specimen since it is easily collected and readily available
Enumerate other sources of the blood group soluble substances
Serum
Sweat
Tears
Semen
Types of Blood Donation
Directed: blood is intended for the use of specific patient
Allogenic: blood donation is intended for the use of general patient population
Autologous: blood donated by the owner for future use
Apheresis: takes only the specific component of the blood and the remaining components are returned back to the donor
Types of Blood Donor:
Voluntary non-remunerated: donates blood on his own free will without receinving any payment
Professional/ Commercial: donates blood for the sake of money
Family/replacement: allows family and friends to make donations to replace blood that was utilized by you
Steps in blood donation
- Donor recruitment and registration
- Medical history
- Physical examination
Donor recruitment and registration
- name
- date and time of donation
- address
- gender
- age
- DOB
Medical history
ensure the benefit of both donor and recipient
in a form of questionnaires
Physical examination
Allogeneic age req. = 17 - 65 years old Weight: 110 lbs/ 50 kg. - 450 ml of blood: 63 ml anticoagulant Temperature: 37.5 degrees Celsius Pulse rate: 50-100 beats per minute Blood pressure: systolic: 90-160 mmhg diastolic: 60-100 mmhg Hemoglobin: autologous: 11 g/dl allogeneic 12.5 g/dl Hematocrit: autologous: 33% allogeneic: 38%
Serologic Tests
ABO/Rh Antibody screen HBsAG Anti-HBc Anti-HCV ANTI-HIV 1/2 Anti-HTLV Syphilis Malaria
Deferral
Permanent - high risk history of aids, includes:
a. men sex with men
b. hemophiliacs
c. IV drug abusers
d. sex for money
e. positive for AIDSs
f. viral hepatitis
g. jaundice of unknown origin
h. severe liver, cardiac, lung disease
i. autoimmune disorders
Temporary
For three years: malaria
For one year: Hepa B, rape, tattoo, jail, transfusion, travel areas endemic for malaria, syphilis and gonorrhea, rabies vaccination
For two months: blood donation
For one month: German measles vaccination, isotretinoin, finasteride for prostatic hyperplasia
For six weeks: delivery of baby (AABB) 9 months after child birth
For two weeks: after vaccination with oral polio, measles, mumps or yellow fever
For 48 hours: whole blood donation deferred after hemapheresis
Direct Antihuman Globulin Test (DAT)
demonstrate in vivo coating of red cells with antibodies or complement, in particular IgG and C3d ( in vivo sensitization)
Antihuman Globulin Test (IAT)
also known as Coomb’s test, detects the presence of unexpected antibodies in the patient’s serum that are able to coat antigens in type “O” red cells in vitro. It is based on the principle that AHG’s obtained from immunized non human species bind to human globulins.
What is Coomb’s reagent? How is it prepared?
Coomb’s reagent is a reagent used in the testing of AHG. It is prepared by an injection of a serum into rabbits to produce antihuman serum.
Uses of DAT
detects in vivo sensitization of RBCs with IgG or complement components
Uses of IAT
detects incomplete Ab to potential donor RBCs or to screening cells
False results in Antihuman Globulin test
False + - improper specimen - Bacterial contamination - Polyagglutinate cells - over reading - overcentrifugation False - - Improper washing - Interruption testing - Improper temperature - Undercentrifugation
When is DAT performed?
- detect hemolyic disease of newborn
- hemolytic transfusion reaction
- Autoimmune
When is IAT performed?
- determination of RBC phenotype using antisera
- detect incomplete antibody to potential donor RBC
Major Crossmatching
- consisting of mixing the patient’s serum with donor red cells (PS-DR)
Minor Crossmatching
- consisting of mixing the donor’s serum with patient red cells (PR-DS)
Interpretation of crossmatching
1. Protein Phase - 0 0 Thermo Phase - 0 0 AHG Phase - 0 0 Interpretation = Blood is compatible both in major and minor crossmatch. Blood is safe for transfusion. 2. Protein Phase: + 0 Thermo Phase: _ 0 AHG Phase: _ 0 Interpretation = Blood is incompatible in major crossmatch but compatible in minor crossmatch. Blood is not safe for transfusion. 3. Protein Phase: + + Thermo Phase: _ _ AHG Phase: _ _ Interpretation: Blood is incompatible both in major and minor crossmatch. Blood is not safe for transfusion. 4. Protein Phase: 0 + Thermo Phase: 0 _ AHG Phase: 0 _ Interpretation: Blood is compatible in major crossmatch but incompatible in minor crossmatch. Blood can be transfused but with caution.
State the significance of compatibility test in transfusion medicine.
Compatiblity testing is performed to determine if a particular unit of blood can be transfused safely into a certain patient. It is a series of procedure to ensure safety of blood for transfusion.
Differentiate major from minor crossmatching.
In major crossmatching recipient serum is used against donor RBC, the minor crossmatch is to test opposite compatibility: donor’s plasma/serum agains recipient red cells.
What incompatibilities are detected in the:
a. Protein Phase: incompatibilities in the ABO system with hemolysis. May indicate presence of anti-A or anti-B. Caused by cold agglutinins.
b. Thermo Phase: presence of low tittered anti-TH antibody that does not react on immediate spin.
c. Antihuman Globulin Phase: acquired hemolytic anemia will be found in the AHG phase. Antibodies that react in AHG test is called “third order”.
Whole Blood
1-6 degrees Celsius
ACD, CPD or CP2D = 21 days
CPDA1 = 35 days
Packed RBC
1-6 degrees Celsius
ACD, CPD or CP2D = 21 days
CPDA1 = 35 days
Open system when packing = 24 hours