Midterms: AHG & Pretransfusion

Question 1

ANTI-HUMAN GLOBULIN (AHG) REAGENT
• Other name:

Answer 1

Coombs Reagent

Question 2

Reagent that has been prepared by injecting animals (rabbits) with
human antibody molecules and complement proteins. The sensitized
animal which produced antibodies against IgG and complement
proteins

Answer 2

AHG REAGENT

Question 3

This reagent contains a blend of antibodies for IgG (Anti-IgG)
and complement proteins (Anti-C3b, Anti-C3d)

Answer 3

Polyspecific Anti Human Globulin Reagent

Question 4

This reagent contains antibody of only one specificity

Answer 4

MONOSPECIFIC ANTI HUMAN GLOBULIN (COOMBS’) REAGENT

Question 5

Describe AHG Reagent

Answer 5

• AHG antibodies act as bridges that induce agglutination to RBCs coated with human IgG or complement.

Question 6

Anti human globulin reagent is used to detect

Answer 6

IgG or complement
sensitized on red blood cells.

Question 7

Explain neutralization

Answer 7

Any unbound antibody or complement present in serum can
potentially bind to the AHG reagent and inhibits its reaction with
antibody or complement molecules attached to the RBC

Question 8

Any unbound antibody or complement present in serum can
potentially bind to the AHG reagent and inhibits its reaction with
antibody or complement molecules attached to the RBC

Answer 8

Neutralization

Question 9

Used to detect in vivo-sensitized red blood cells withimmunoglobulin, or complement or both.

Answer 9

DAT

Question 10

Applications for DAT

Answer 10

Alloimmune Hemolysis
Rh HDN
HDFN
Autoimmune Hemolysis
Drug induce-immune mediated hemolysis

Question 11

Drug induced-immune mediated hemolysis consist of:

Answer 11

Methyldopa
Penicillin (High dose)
Cephalosporin
Procainamide

Question 12

Can you name examples of blood group autoantibodies?

Answer 12

Autoanti I : Infectious mononucleosis
Autoanti P: PCH, Donath Landsteiner, Cold Autoantibody
Autoanti Kidd: Proteus Mirabilis

Question 13

Applications of IAT

Answer 13

Crossmatching

-Detection of antibodies in pregnant women
-Screening and identification of antibody specificity using a panel of
red blood cells with known antigenic profile
-Determination of red blood cell phenotype using known antisera
(e.g. Du testing)
• Titration of incomplete antibodies

Question 14

Factors Affecting AHG TEST

Answer 14

Ratio of serum to cells
Reaciton Medium
Temperature
Incubation Time
Washing of cells
Saline for Washing
Addition of AHG
Centrifugation

Question 15

SALINE FOR WASHING
• Ideally, it should be fresh or alternately buffered to a _______

Answer 15

ph 7.2-7.4

Question 16

ERRORS IN AHG TESTING FALSE -

Answer 16

Failure to wash cells
Interruption in testing
Improper procedure
Improper reagent storage
Neutralization
Saline Soluotion is Old
aHG is aged

Question 17

Errors in AHG False +

Answer 17

Particles or contaminants
Improper procedure
Cells with positive DAT results
Complement coated RBCS

Question 18

The cells are used as a quality control measure for negative indirect direct anti globulin test performed in test tubes,

Answer 18

Coombs control red cells

Question 19

Define pretransfusion compatibility testing

Answer 19

series of testing procedure and processes with the objective of ensuring
the best possible results of a blood transfusion

Question 20

series of testing procedure and processes with the objective of ensuring
the best possible results of a blood transfusion

Answer 20

Pre-transfusion compatibility testing

Question 21

Enumerate the components included in compatibility testing.

Answer 21

ABO GROUPING
RH TYPING
CROSSMATCHING
HISTORICAL RECORD CHECK
Screening unexpected antibodies
Alloantibody identification

Question 22

State the fundamental rule in the selection of donor blood in crossmatch

Answer 22

ABO and Rh- group specific blood between donor and recipient
• Donor unit- should be the same as the Pt’s ABO and Rh group.

Question 23

most important consideration in pretransfusion compatiblity testing

Answer 23

Positive patient identificaition