MIDTERM LABORATORY L1: WEAK-D TESTING

Question 1

test performed when Rh result is negative

Answer 1

weak-D testing

Question 2

phenotype of individuals with weak-D

Answer 2

Du type

Question 3

is Du type considered Rh positive or negative?

Answer 3

Rh positive

Question 4

3 common mechanisms of weak-D

Answer 4

Genetic weak D
C trans
Partial D

Question 5

mechanism where D antigen appears to be complete but fewer in numbers

Answer 5

Genetic Weak D

Question 6

mechanism where there is position effect due to interaction of the gene

Answer 6

C trans

Question 7

mechanism where there is one or more of D epitopes within the protein missing/altered; weaker agglutination w/ D reagent

Answer 7

Partial D (D Mosaic)

Question 8

why is antibody production not stimulated by weak D phenotype

Answer 8

Because Rh D protein changes occur inside the red cell and is not exposed

Question 9

how can weak expression be detected

Answer 9

Indirect Coomb’s Test

Question 10

how does Indirect Coomb’s Test work

Answer 10

red cells will be synthesized in vitro, and then bridged with Coomb’s reagent

Question 11

what is Coomb’s reagent composed of

Answer 11

Anti-Human Globulin

Question 12

color of Anti-Human Globulin solution

Answer 12

green

Question 13

color indicator

Answer 13

Janus green

Question 14

is weak D recipient and donor, respectively considered Rh positive or negative?

Answer 14

Rh negative for recipient
Rh positive for donor

Question 15

T or F:
weak D test is required for recipients

Answer 15

F

Question 16

what reagents should be dropped in px labeled tube

Answer 16

1 drop of anti-D and 1 drop of RCS

Question 17

what reagents should be dropped in negative control tube

Answer 17

1 drop of 22% Bovine Serum Albumin, then 1 drop of RCS

Question 18

what reagents should be dropped in positive control tube

Answer 18

1 drop of anti-D, then 1 drop of known D-Positive RCS

Question 19

how to incubate the 3 tubes

Answer 19

in a water bath at 37C for 15 mins

Question 20

after incubation, px tube shows no agglutination, what is the next step

Answer 20

1) wash cells 3 times with NSS and decant
2) add 2 drops of AHG rgt to all tubes and mix gently
3) cover w/ parafilm, spin for 15 secs
4) dislodge, grade

Question 21

after incubation px tube shows agglutination, what is the next step

Answer 21

record as Rh positive

Question 22

T or F:
before recording the results, you can place the tube in the rack to avoid spills

Answer 22

F
NEVER place the tube back in the rack before recording of results

Question 23

shaking the tube too hard can cause what discrepancy

Answer 23

false-negative results (fragile agglutinates)

Question 24

inadequate mixing of tube can cause what discrepancy

Answer 24

false-positive

Question 25

reaction of less than 3-4+ in the D or reverse typing tubes can be caused by

Answer 25

shaking tube too hard, leading to false negative

Question 26

grading serological reactions in tube testing: 4+

Answer 26

one solid agglutinate, no free cells

Question 27

grading serological reactions in tube testing: 3+

Answer 27

several large agglutinates, clear background

Question 28

grading serological reactions in tube testing: 2+

Answer 28

medium sized agglutinates, clear background

Question 29

grading serological reactions in tube testing: 1+

Answer 29

small agglutinates, turbid reddish background

Question 30

grading serological reactions in tube testing: 1+w

Answer 30

very small agglutination, turbid background

Question 31

grading serological reactions in tube testing: W+ or +/-

Answer 31

barely visible agglutination, turbid background

Question 32

grading serological reactions in tube testing: MF

Answer 32

mixed field, mixture of agglutinated and unagglutinated red cells

Question 33

grading serological reactions in tube testing: H

Answer 33

complete hemolysis, grossly red supernate, no rbcs present

Question 34

grading serological reactions in tube testing: PH

Answer 34

partial hemolysis, red supernate but some rbcs remain

Question 35

once the reaction is negative, proceed with what test

Answer 35

check cells

Question 36

how many drops of check cells are added

Answer 36

2 drops

Question 37

positive check cells indicate

Answer 37

confirms negative result

Question 38

negative check cells indicate

Answer 38

repeat entire procedure (invalid/improperly done)

Question 39

specimen for weak-d testing

Answer 39

negative test from Rh typing

Question 40

most important step of weak-d testing

Answer 40

washing

Question 41

what are the check cells used in weak-d testing

Answer 41

"O" red cells coated w/ anti-D added to negative anti-D test

Question 42

manner of reporting for (+ grading) anti-D (slide or tube)

Answer 42

Rh positive (+)

Question 43

manner of reporting for (0 grading) anti-D (slide or tube)

Answer 43

Rh negative (-) (initial)

Question 44

manner of reporting for (0 grading) AHG test

Answer 44

Du negative (-)

Question 45

manner of reporting for (+ grading) AHG test

Answer 45

Du positive (+)

Question 46

what happens when a person with Rh negative Du positive receives an ABO compatible Rh positive blood

Answer 46

the person might develop antibody against the missing part in the D antigen (D mosaic)