AHG

Question 1

AHG is also known as?

Answer 1

Coomb’s test

Question 2

AHG

this test is used to?

principle

Answer 2

detect the presence of human globulin molecules either bound to the red cells or free in serum

Question 3

Coomb’s test make use of reagents produced by?

Answer 3

rabbits

which will react to human antibodies

Question 4

used to detect antibody binding to antigen on the surface of RBCs that happens in vivo

Answer 4

Direct Antihuman Globulin Test

Question 5

IAT is used to detect for the?

Answer 5

in vitro sensitization of red blood cells with blood group antibodies

Question 6

reagent that contains anti-IgG and C3D

Answer 6

polyspecific AHG

Question 7

reagent that contains only anti-IgG

Answer 7

Monospecific AHG

Question 8

DAT

in vivo or vitro?

Answer 8

in vivo

Question 9

IAT

in vivo or in vitro?

Answer 9

in vitro

Question 10

storage req for reagent

Answer 10

stored at 2-8 centrigrade and must be at room temperature prior to use

make sure it is beyond its expiry date before using

Question 11

steps of DAT

add — of the AHG reagent to the cell button and resuspend the cells?

what step number?

Answer 11

2 drops of AHG reagent

step 3

Question 12

DAT

after preparing 3-5% rbc suspension, what’s the next step?

Answer 12

place 1-2 drops of cell suspension and wash it with saline 3-4 times

Question 13

steps of DAT

after AHG reagent, what’s the next step?

Answer 13

centrifuge at 3200 rpm for 15 seconds and read and grade the reaction

Question 14

steps of DAT

what will you do if it is negative?

Answer 14

add 1 drop of check cells to the negative test tube.

this should give a positive result

Question 15

steps of IAT

after placing 2 drops of prepared rbc suspension, what’s the next step?

Answer 15

add patient’s serum into the same test tube

Question 16

steps of IAT

incubate the tube at — in a water bath for —

step 4

Answer 16

incubate 37C for 15 minutes

Question 17

steps of IAT

after incubation, what’s the next step?

Answer 17

centrifuge and resuspend then observe for agglutination or hemolysis

Question 18

steps of IAT

if no agglutination, what will u do?

Answer 18

wash the serum-cell mixture 3 times by NSS

after 3rd washing, centrifuge @ 3200 rpm for 15 secs

Question 19

indicates a positive result of DAT

Answer 19

agglutination

Question 20

agglutination in DAT is due to?

Answer 20

in vivo sensitization of antibodies coating to the patient’s RBCs

Question 21

positive result of IAT

Answer 21

agglutination

Question 22

Coomb’s test (AHG) was named after who?

Answer 22

Coombs, Mourant, and Race (1945)

they described a test for detecting nonagglutinating Rh antibodies

Question 23

DAT is used to diagnose —

Answer 23

• HDFN
• HTR
• autoimmune hemolytic anemia

Question 24

IAT is used to demonstrate in vitro reactions between red cells and coating antibodies, as in —

Answer 24

• antibody detection
• antibody identification
• blood goruping
• compatibility testing

Question 25

false + results is caused by — (10)

enumerate

Answer 25

1. improper specimen (refrigerated or clotted)
2. autoagglutinable cells
3. bacterial ocntamination of cells or saline used in washing
4. cells with positive DAT for the IAT
5. saline contaminated with heavy metals or colloidal silica
6. dirty glassware
7. overcentrifugation and overreading
8. polyagglutinable cells
9. preservative-dependent antibody LISS reagents
10. contamianting antibodies in the antihuman globulin reagent.

may cause in vitro complememt

Question 26

false negative may be due to —

enumerate the 7

Answer 26

• inadequate or improper washing of RBCs
• deterioration of reagent or neutralization
• AHG reagent not added
• serum not added in IAT
• serum not reactive because of complement inactivation
• inadequate incubation condition of IAT
• cell suspension either too heavy or too weak
• undercentrifugation
• poor reading technique

Question 27

enumerate the factors affecting the sensitibity of IAT

Answer 27

• temperature
• ionic strength
• ratio of serum to cells
• pH of the reaction mixture
• incubation time