Lecture 7

Question 1

Blood Bank sample requirements

Answer 1

patient’s full name and unique identity number
Writing must be legible and indelible
Date of collection
Sample must be collected within 3 days of scheduled transfusion
initials or signature of the person who collected the sample

Question 2

Hemolyzed samples

Answer 2

cannot be used for testing
hemolysis caused by activation of complement by antigen-antibody complexes will be masked

Question 3

To avoid contamination blood

Answer 3

samples should not be taken from intravenous tubing lines

Question 4

ABO Grouping

Answer 4

the most critical pretransfusion serologic test
Tube tests offer greater sensitivity

Question 5

Group I Discrepancy

Answer 5

occur between forward and reverse groupings owing to weak or missing antibodies
most common discrepancy

Question 6

Group I Discrepancy: reason

Answer 6

depressed antibody production
Newborn/elderly
Leukemia (CLL)
Lymphoma
Immunosuppresive drugs

Question 7

Resolution of Group I Discrepancies

Answer 7

enhance the reverse group reaction
incubating the patient serum with reagent A1 and B cells at room temperature(25ºC) for approximately 15 to 30 minutes

Question 8

What if Group 1 resolution doesn’t work?

Answer 8

serum-cell mixture can be incubated at 4ºC for 15 to 30 minutes

Question 9

Group II Discrepancies

Answer 9

Occurs between forward and reverse groupings owing to weak or missing antigens

Question 10

Group II Discrepancies: Causes

Answer 10

Subgroups of A and/or Subgroups of B being present
Leukemias
Hodgkin’s disease
Acquired B” Phenomena
Antibodies to low incidence antigens

Question 11

Group II resolution: Possible weak subgroup of A

Answer 11

Test cells with anti-A,B reagent
Test with Anti-A1 lectin
May require genotype testing to confirm

Question 12

Group II resolution: Possible acquired B

Answer 12

Treating red cell with acetic anhydride re-acetylates the surface molecules

Question 13

Group III Discrepancies

Answer 13

Occurs due to protein or plasma abnormalities

Question 14

Group III discrepancies: Causes

Answer 14

Elevated globulin levels like:
Waldenstroms macroglobulinemia
Multiple Myeloma
Hodgkin’s disease
Rouleaux due to elevated Fibrinogen
Wharton Jelly

Question 15

Group III discrepancies: Resolution

Answer 15

Cells must be washed to alleviate problem

Question 16

Group IV discrepancies

Answer 16

Polyagglutination-spontaneous RBC Agglutination
Bacterial contamination

Question 17

Warm autoantibodies

Answer 17

Presence of warm autoimmune antibodies. Most common
reactive at 37o C

Question 18

Cold autoantibodies

Answer 18

anti-I and anti-H and anti-IH
Benign cold reacting autoantibodies are present in all normal human sera

Question 19

Resolution to Group IV Discrepancies

Answer 19

If the poly agglutination is suspected, lectin studies should be performed

Question 20

Potent Cold Autoantibodies

Answer 20

○ cause spontaneous agglutination, causing positive Coomb’s test (DAT)
resolved by incubating red cells at 37C for a short period of time

Question 21

Warm Antibodies

Answer 21

When expected of causing a false positive reaction in the forward grouping the cells can be treated to a gentle heat elution at 45C for the cells to be reliably typed

Question 22

Unexpected ABO isoantibodies

Answer 22

react at room temperature with the corresponding antigen present on the reagent cells
A2 and A2B individuals: produceanti-A1, or A1
A1B: produce anti-H

Question 23

Unexpected Alloantibodies

Answer 23

may cause a discrepancy in the reverse grouping
In this situation- a panel should be performed with the patient’s serum

Question 24

Cis-AB

Answer 24

inheritance of both AB genes from one parent carried on one chromosome and the O gene inherited from the other parent
results in the offspring inheriting three ABO genes

Question 25

Rh Grouping

Answer 25

performed using anti-D blood grouping serum
Rh Controls must be run alongside, to avoid incorrect designation of Rh-negative patients as Rh-positive

Question 26

If the Rh-control is positive?

Answer 26

Rh grouping test is invalid and must be rerun
DAT should be performed to determine whether autoantibodies is responsible for the positive Rh control

Question 27

If Rh group of the recipient cannot be established and transfusion is essential

Answer 27

Rh-negative blood should be given

Question 28

Antibody Screen

Answer 28

The patient’s serum or plasma must be tested for unexpected antibodies

Question 29

Antibody Screen offers several advantages over direct crossmatch testing

Answer 29

group O red cells that are known to carry optimal representation of important blood group antigens
Testing can be performed well in advance of the anticipated transfusion

Question 30

Antibodies regarded as always being potentially clinically significant

Answer 30

ABO, Rh, Kell, Duffy, Kidd, SsU

Question 31

Antibodies that may sometimes be clinically significant

Answer 31

Lewis (Lea), MN, P,1 Lutheran (Lua, Lub), Cartwright (Yta)

Question 32

Rarely seen antibodies that are clinically significant

Answer 32

Leb, Chido/Rogers (Cha/Rga), York (Yka), Sda, Xga

Question 33

Crossmatch Testing

Answer 33

testing of the patient’s serum with the donor cells
“compatibility test”

Question 34

Two main functions for performing the crossmatch

Answer 34

a final check of ABO compatibility between donor and patient
may detect the presence of an antibody in the patient’s serum that will react with antigens on the donor RBCs that was not detected in the antibody screening

Question 35

Crossmatch Testing: Results

Answer 35

A jagged or firm button edge is indicative of a positive reaction = incompatible
smooth swirling of free cells off the RBC button indicates a negative reaction = compatible

Question 36

Whenever the crossmatch test result is positive

Answer 36

results of the autocontrol and antibody screening test should be reviewed

Question 37

Causes of positive results in the serologic crossmatch

Answer 37

Incorrect ABO grouping of the patient or donor
Resolution - Repeat testing