Test 3b Review Sheet Information

Question 1

What are the 7 parts of a complete Compatibility Test?

Answer 1

1. Request to perform testing and prepare components
2. Receipt of acceptable blood sample
3. Performance of an ABO blood group, Rh type, and a test for unexpected antibodies (Ab screen) (Type & Screen)
4. Review of previous records for blood type and unexpected antibodies (history/ records)
5. Selection of crossmatch procedure
6. Selection of blood for transfusion
7. Performance of a crossmatch

Question 2

Name the blood groups which are known to cause hemolysis

Answer 2

ABO
P
Lewis
Kidd 
Vel

Question 3

What is the purpose of the Antiglobulin Test (AGT)?

Answer 3

To detect bound IgG and/or complement on the RBCs

Question 4

Name the 3 types of AHG reagent

Answer 4

Polyspecific: IgG and C3d
Monospecific IgG
Monospecific C3d

Question 5

How does AHG work?

Answer 5

Any cell coated with antibodies will be complexed with AHG, and the clumps will form macroscopic or microscopically

Question 6

Name the 2 types of AHG test, and describe them

Answer 6

DAT- direct antiglobulin test: detects in vivo coating of antibodies
IAT- indirect antiglobulin test: detect in vitro coating of antibodies onto cells

Question 7

Describe unexpected antibodes

Answer 7

antibodies to red call antigens that are not expected (other than ABO antibodies)

Question 8

What is the purpose of the antibody screen?

Answer 8

To detect unexpected red cell antibodies in the patients serum or plasma

Question 9

What types of cells are used in antibody screening and identification?

Answer 9

Group O

Rh positive and negative

Question 10

What are enhancement agents, how do they work, and name them

Answer 10

Substances added to the testing system to increase the binding of antigens to antibodie
Albumin
LISS
polybrene
PEG

Question 11

What are Coombs Control Cells and what is their purpose?

Answer 11

RBCs coated with human IgG antibody that are added to a negative AHG tube to ensure propoer function fo the AHG reagent

Question 12

What does it mean if the CCC do not agglutinate?

Answer 12

AHG reagent was ommitted or inactivated, or the tests system was not washed adequately to remove all protein

Question 13

Describe the purpose of Autocontrol and what it means if it is positive

Answer 13

Testing the patient’s serum or plasma with their won RBCs to determine if autoantibodies are present.
If it is positive, the patient may have free autoantibody in their serum or plasma (usually DAT is run next and is positive)

Question 14

What tests are performed on a patient’s sample in order to administer units of packed RBCs?

Answer 14

ABO/Rh
Antibody screen
Crossmatch

Question 15

If an antibody screen on a patient is negative, what is the chance that a crossmatch would be INCOMPATIBLE?

Answer 15

Less than 1%

Question 16

How are enzymes helpful in antibody identification?

Answer 16

Enzymes destroy Duffy and MNS antigen. Enzymes also enhance some reactions (such as Rh)

Question 17

What is the difference between a major and minor crossmatch?

Answer 17

Major: patient’s serum/plasma with donor RBCs
Minor: Patient’s RBCs with donor serum/plasme (not used anymore)

Question 18

What can be used to assist in clotting of a sample from patients on anticoagulant therapy?

Answer 18

Thrombin or glass beads may be added to enhance clotting. If heparin is present, protamine sulfate may speed clotting

Question 19

What are the limitations to Compatibility Testing? What percent of antibodies are NOT detectable after 5 years?

Answer 19

Patient may have previous antibody that is too low to detect

1/3 of alloantibodies are NOT detectable after 5 years

Question 20

What must be checked before issuing blood to a person from the blood bank? What must be checked before hanging a unit on a patient?

Answer 20

Recipients name
ID#
ABO/Rh
Donor Unit #
Compatibility test result

Question 21

What is informed consent?

Answer 21

Physician or designee must educate patient as to the risks involved in transfusions of blood and blood products, and must be signed by patient or representative prior to receipt of blood (unless severe emergency).

Question 22

What is the Maximum Surgical Blood Order and how does it work?

Answer 22

Average number of units usually needed by patients for specific surgeries set up on all patients in advance.

Question 23

What is an elution and when is it used in Blood Bank?

Answer 23

Procedure to remove antibody from the RBC surface (coated in vivo). Acid, heat or freeze are techniques used.

Question 24

What is an adsorption and when is it used in Blood Bank?

Answer 24

Procedure used to remove autoantibody from patient’s serum or plasma. Pull auto out of the patient’s serum so that clinically significant alloantibodies can be detected. Used in Warm Autoimmune Hemolytic Anemias (WAIHA).