Blood Bank: AB ID and Pretransfusion Testing Flashcards Preview

Med Lab Tech Fall 2016 > Blood Bank: AB ID and Pretransfusion Testing > Flashcards

Flashcards in Blood Bank: AB ID and Pretransfusion Testing Deck (147):
1

What are the types of unexpected antibodies?

  • Immune alloantibodies
  • Naturally occurring antibodies
  • Passively acquired antibodies

2

What type of antibodies are produced in response to RBC stimulation through transfusion, transplantation, or pregnancy?

Immune alloantibodies

3

What type of antibodies may form as a result of exposure to environmental sources such as pollen, fungus, and bacteria, which have similar structures to some RBC antigens.

Naturally occurring antibodies

4

What are passively acquired antibodies?

Antibodies produced in one individual and then transmitted to another via plasma-containing blood components or derivatives such as intravenous immunoglobulin (IVIG)

5

These are antibodies that decrease the survival of RBCs possessing the target antigen.

Clinically significant antibodies

6

These antibodies are typically IgG that react at 37C or that react in the AHG phase of the IAT

Clinically significant antibodies

7

These are directed against antigens expressed on one's own RBCs and may mask the presence of clinically significant alloantibodies.

Autoantibodies

8

What is the traditional method for detecting antibodies?

The indirect antiglobulin test performed in a test tube

9

In the test tube for IAT, the patient's ________ or ________ is mixed with _________ that have known antigen content

Plasma or serum is mixed with RBCs that have known antigen content

10

What is the immediate spin phase used to detect?

Antibodies reacting at room temperature and possibly clinically insignificant cold antibodies

11

IAT must include these phases

37C and AHG

12

What is another name for AHG reagent?

Coombs' serum

13

The RBC reagents used in the antibody screen come from group ____ individuals who have been typed for the most common and most significant RBC antigens

Group O

14

Antibodies that react more strongly with cells having homozygous antigen expression are said to show _______

Dosage

15

True or False: As RBCs age, antigen expression begins to weaken

True

16

Definition: The difference in electrical potential between the surface of the RBC and the outer layer of the ionic cloud is called the ______ _________

Zeta potential

17

This enhancement reagent contains glycine in an albumin solution. In addition to lowering the zeta potential, it increases the uptake of antibody onto the RBC during the sensitization phase, increasing the possibility of agglutination.

Low Ionic Strength Solution (LISS)

18

This enhancement reagent removes water from the test system, thereby concentrating any antibodies present and increasing the degree of RBC sensitization

Polyethylene glycol (PEG)

19

This enhancement reagent can cause nonspecific aggregation of cells, so centrifugation after 37C incubation is not performed.

Polyethylene glycol (PEG)

20

Adding this reagent allows for the agglutination of incomplete antibodies

AHG

21

What are check cells?

Check cells are Rh-positive RBCs that have been coated with anti-D

22

What must be done if the Coombs' control cells fail to agglutinate?

The antibody screen must be repeated from the beginning

23

Antibodies of the Ig__ class react best at room temperature and lower and are capable of causing agglutination at immediate spin.

IgM

24

Antibodies of the Ig__ class react best at the AHG phase

IgG

25

Anti-N, anti-I, and anti-P1 are frequently Ig__

IgM

26

Rh, Kell, Kidd, Duffy, and Ss antigens are usually Ig__

IgG

27

True or False: Lewis and M antibodies may be IgG, IgM, or a mixture of both

True

28

What is the autologous control?

The patient's RBCs tested against the patient's serum or plasma in the same manner as the antibody screen

29

What does a positive antibody screen and negative autologous control indicate?

A positive antibody screen and a negative autologous control indicate the detection of an alloantibody

30

What might a positive autologous control mean?

Positive autologous control may indicate the presence of autoantibodies or antibodies to medications

31

If a patient has been recently transfused (within the past 3 months) a positive autologous control may be cause by what?

Alloantibodies coating circulating donor RBCs

32

When screen cells yielding a positive reaction react at the same phase and strength what should be suspected?

A single antibody specificity

33

____________ should be suspected when the autologous control is positive.

Autoantibodies

34

What antibodies cause in vitro hemolysis? (4)

  • Anti-Lea
  • Anti-Leb
  • Anti-PP1Pk
  • Anti-Vel

35

Mixed field agglutination is associated with ______ and ___________ antibodies

  • Anti-Sda
  • Lutheran antibodies

36

How do you fix rouleaux?

Saline replacement

37

What factors may influence the sensitivity of the antibody screen?

  • cell-to-serum ratio
  • temperature and phase of reactivity
  • length of incubation
  • pH

38

What is the cell-to-serum ratio?

2 drops of serum to 1 drop of RBC suspension

39

When an antibody is weak, the amount of serum in the antibody screen may be increased to what?

4-10 drops

40

True or False:

It is okay to increase the amount of serum in an antibody screen when potentiators have been included

False- serum increase (4-10 drops) should not be used when potentiators are included in the test

41

What are 2 common cold autoantibodies?

Anti-I and anti-IH

42

If incubation is too short what happens?

Too few RBCs will be sensitized to be detected by routine methods

43

If incubation is too long what happens?

Bound antibody may begin to dissociate from the RBCs

44

At what pH do most antibodies react best?

Neutral- between 6.8-7.2

45

Acidifying the antibody screen may help distinguish anti-___ from other antibodies

anti-M

46

What antibodies are typically seen at immediate spin?

  • Cold autoantibodies (I,H,IH)
  • Lea, Leb
  • M, N
  • P1
  • Lua

47

What antibodies are typically seen at 37C incubation?

  • Potent cold (IgM) antibodies (especially those causing hemolysis)
  • some warm antibodies, if high in titer (D, E, and K)

48

What antibodies are typically seen at the AHG phase?

  • Rh antibodies
  • Kell
  • Duffy
  • Kidd
  • S,s
  • Lub
  • Xga

49

What immunoglobulin class is typically seen at the IS phase?

IgM

50

What immunoglobulin class is typically seen at the 37C incubation phase?

Usually IgG and IgM that activate complement

51

What immunoglobulin class is typically seen at the AHG phase?

IgG

52

Are antibodies at the IS phase clinically significant?

No

53

Are antibodies at the 37C phase clinically significant?

Yes

54

Are antibodies at the AHG phase clinically significant?

Yes

55

This antibody is more frequently associated with persons of African descent

Anti-U

56

What type of antibodies should be suspected in a patient with no transfusion or pregnancy history?

Naturally occurring antibodies

57

In a patient transfused within the past 3 months, what would a positive DAT indicate?

A delayed hemolytic transfusion reaction

58

Positive reactions caused by donor RBCs usually show what type of agglutination?

Mixed-field

59

What low-prevalence antigens are rarely expressed homozygously? (4)

  • K
  • Kpa
  • Jsa
  • Lua

60

What 2 reagents are useful in stripping antibody from the RBC surface, while leaving the membrane intact to allow phenotyping?

Chloroquine diphosphate and acid glycine/EDTA

61

What antigens are denatured when using acid glycine/EDTA?

Kell antigens

62

What antigens may show diminished reactivity with the cholorquine diphosphate method?

Rh antigens

63

What enzyme is commonly used to treat RBCs?

Ficin

64

What are 3 other enzymes (aside from ficin) that may be used to treat RBCs?

  • Papain
  • Bromelin
  • Trypsin

65

How do enzymes modify RBCs?

They remove sialic acid residues and denature or remove glycoproteins

66

What antigen-antibody reactions are inactivated by proteolytic enzymes?

  • Duffy
  • MNSs
  • Xga

67

What antigen-antibody reactions are enhanced by proeolytic enzymes?

  • Rh
  • Kidd
  • Lewis
  • P1
  • I
  • ABO

68

What is anti-P1 neutralized by?

  • Hydatid cyst fluid,
  • pigeon droppings,
  • turtledoves' egg whites

69

What is anti-Lewis neutralized by?

  • Plasma or serum
  • saliva

70

What are anti-Chido and anti-Rodgers neutralized by?

  • Serum (contains complement)

71

What is anti-Sda neutralized by?

Urine

72

What is anti-I neutralized by?

Human breast milk

73

In this method, the antigen-antibody complex is composed of solid precipitates and is removed from the test system by centrifugation

Adsorption

74

What is the direct antiglobulin test is used to detect?

In vivo sensitization of RBCs

75

This technique is used to release, concentrate, and purify antibodies.

Elution technique

76

True or false:

A fourfold or greater increase in titer or an increase in score of 10 or more is considered to be significant

True

77

Antibodies are excluded using RBCs that are homozygous for the corresponding antigen because:

a. antibodies may show dosage

b. multiple antibodies may be present

c. it results in a P value of .05 for proper ID of the antibody

d. all of the above

a. antibodies may show dosage

78

A request for 8 units of packed RBCs was received for patient LF. The patient has a negative antibody screen, but one of the 8 units was 3+ incompatible at the AHG phase. Which of the following antibodies may be the cause?

a. Anti-K

b. Anti- Lea

c. Anti-Kpa

d. Anti-Fyb

c. Anti-Kpa

79

The physician has requested 2 units of RBCs for patient DB, who has 2 antibodies, anti-L and anti-Q. The frequency of antigen L is 45% and the frequecy of antigen Q is 70% in the donor population. Approximately how many units will need to be antigen-typed for L and Q to fill the request?

a. 8

b. 12

c. 2

d. 7

b. 12

80

Anti-Sda has been identified in patient ALF. What substance would neutralize this antibody and allow detection of other alloantibodies?

a. saliva

b. hydatid cyst fluid

c. urine

d. human breast milk

c. urine

81

Patient JM appears to have a warm autoantibody. She was transfused 2 weeks ago. What would be the next step performed to identify any alloantibodies that might be in her serum?

a. acid elution

b. warm autoadsorption using autolougous cells

c. warm differential asdorption

d. RESt adsorption

c. warm differential asdorption

82

Which of the following methods may be employed to removed IgG antibodies taht are coating a patient's RBCs?

a. adsorption

b. elution

c. neutralization

d. titration

b. elution

83

A technologist has decided to test an enzyme-treated panel of RBCs against a patient's serum. Which of the following antibody pairs could be separated using this technique?

a. Anti-Jka and anti-Jkb

b. Anti-S and anti-Fya

c. Anti-D and anti-C

d. Anti-Jka and anti-Fya

d. Anti-Jka and anti-Fya

84

An antibody demonstrates weak reactivity at the AHG phase when using a tube method with no enhancement reagent and monospecific anti-IgG AHG reagent. When repeating the test, which of the following actions may increase the strength of the positive reaction?

a. adding an enhancement reagent, such as LISS or PEG

b. decreasing the incubation time from 30 mins to 10 mins

c. employing the prewarm technique

d. decreasing the incubation temperature to 18C

a. adding an enhancement reagent, such as LISS or PEG

85

What is an alloantibody?

An antibody produced after exposure to a genetically different, or nonself, antigen of the same species.

86

What is an autoantibody?

An autoantibody is an antibody reactive against one's own red cell antigens

87

Cold reactive autoantibodies are ____ whereas warm reactive autoantibodies are usually ____

  • IgM
  • IgG

88

Examples of cold reavtive autoantibodies include all but which of the following:

A. autoanti-I

B. autoanti-e

C. autoanti-H

D. autoanti-IH

B. autoanti-e

89

Cold reacting IgM autoantibodies that are active at or near body temperature cause:

a. paroxysmal cold hemaglobinuria

b. cold hemagglutinin disease

b. cold hemagglutinin disease

90

Cold reacting IgG autoantibodies that are biphasic in nature, binding to red cells at low temperatures and fixing complement, with hemolysis occurring when the coated red cells are warmed to 37C describes:

a. paroxysmal cold hemoglobinuria

b. cold hemagglutinin disease

a. paroxysmal cold hemoglobinuria

91

Warm reactive autoantibodies are usually clinically significant because:

a. The autologous red cells will be sensitized in vivo and may not survive normally

b. the autoantibody will elute from the red cells in vivo and cause urticaria

a. The autologous red cells will be sensitized in vivo and may not survive normally

92

Why are autoantibodies sometimes identified in a patient's serum as well as on their red cells?

 

Once the amount of antibody produced exceeds the number of antibody-binding sites on the RBCs, the antibody will "spill over" into the serum

93

What is the purpose of an elution?

Elution is a technique used to dissociate IgG antibodies from sensitized RBCs. The recovered antibody is called and eluate and can be tested, like serum, to determine the antibody's specificity.

94

Why is the last wash tested when performing an elution?

 

To determine the fficiency of the washing process, supernatant fluid from the final wash phase should be tested for antibody activity and should be inert

95

At what phase is an eluate read?

a. IS

b. 37C

c. AHG

c. AHG

96

A warm autoadsorption is performed to remove autoantibody from the serum in order to rule out the presence of any underlying ____________.

Alloantibodies

97

A warm autoadsorption is performed only if the patient has not received blood in the last:

a. 24 hours

b. 2 weeks

c. 3 months

d. 3 days

c. 3 months

98

You have no reactions on an IS panel. You add LISS and incubate at 37C for 15 minutes. After incubation, you observe 2+ reactions on all panel cells. At AHG, no reactivity is seen. You perform a DAT, but it is negative. What could explain these findings?

a. Patient has an antibody to the reagent LISS

b. Patient has a warm reacting autoantibody

c. Patient has a cold reacting autoantibody

d. Patient has anti-k

a. Patient has an antibody to the reagent LISS

99

List demographic data or historical information which might be useful to have when resolving antibody problems

  • sex
  • diagnosis
  • age
  • race
  • transfusion history
  • pregnancy history
  • medications, IV's taken

100

What are enzymes used for?

Fy, M, N, S

Destroys, diminishes, or enhances antigen reactivity

101

What is adsorption used for?

Selective removal of one antibody to facilitate identification of others

102

What is neutralization used for?

Exposure of presumed antibody to selected antigen, thus removing it

103

What is chloroquine diphosphate used for?

Removes IgG antibodies from the surface of sensitized RBC's without altering the RBC antigens.

Cannot be accurately typed for Duffy, Kidd, S, or s antigens

104

What is a titer used for?

Determines the relative quatity of an RBC antibody by testing serial twofold dilutions of serum against an antigen-positive RBC

105

Which of the following antibodies is usually nonreactive when red cells used for testing are first treated with proteolytic enzymes:

a. anti-E

b. anti-K

c. anti-I

d. anti-Fyb

d. anti-Fyb

106

What is the optimal temperature of reactivity for anti-E?

a. 56C

b. 37C

c. 22C

d. 4C

b. 37C

107

True or False:

Anti-Jka may react more strongly when complement is added to the test system

True

108

Anti-Fya , anti-c, anti-Jka, anti-S, anti-K, and anti-E are predominantly what immunoglobulin class?

IgG

109

Anti-I and Anti-P1 are predominantly what immunoglobulin class?

IgM

110

Which of the following statements is false concerning rouleaux:

a. rouleaux results from abnormalities of serum protein concentrations

b. rouleaux characteristically appears microscopically as a "stack of coins"

c. rouleaux is an example of true agglutination

d. rouleaux is dispersed by the saline replacement technique

c. rouleaux is an example of true agglutination

111

Why does anti-I react poorly or not at all with cord cells?

Because cord cells are rich in i and I is almost undetectable

112

What is the time limit for use of a specimen to perform compatibility testing when the patient has been transfused or pregnant within the last 3 months?

3 days

113

How will a positive DAT on the donor cells affect the antiglobulin crossmatch?

A positive DAT on donor cells will cause the antiglobulin crossmatch to appear incompatible

114

The purpose of an immediate spin crossmatch is to:

a. detect in vivo sensitization of patient's RBCs

b. detect ABO incompatibilities due to Anti-A, Anti-B, or Anti-A,B

c. prevent detection of rouleaux

b. detect ABO incompatibilities due to Anti-A, Anti-B, or Anti-A,B

115

Pretransfusion of compatilbility testing includes:

  1. ABO and Rh(D) grouping performed on donor and recipient samples
  2. screening of the donor's and patient's serum for unexpected antibodies
  3. Coagulation studies
  4. crossmatch

a. 1 and 2

b. 2 and 3

c. 1, 3, and 4

d. 1, 2, and 4

d. 1, 2, and 4

116

The primary purpose of pretransfusion or compatibility testing is to:

a. detect abnormal fibrinogen levels in the donor's serum

b. ensure that the patient will not form an alloantibody to transfused red cells

c. ensure the best possible results of a blood transfusion

c. ensure the best possible results of a blood transfusion

117

Which of the following tests in NOT REQUIRED by the AABB Standards to be performed on donor blood before it can be issued for transfusion?

a. HLA typing

b. ABO and Rh (D) typing

c. Antibody screen

D. HBsAg

a. HLA typing

118

What is rouleaux and how is it dispersed?

Rouleaux is a term which describes the appearance of red blood cells as stacked coins when viewed under a microscope. It is caused by abnormal serum proteins. Rouleaux may be dispersed by the addition of saline to the test system (saline replacement)

119

When is it appropriate to use an electronic crossmatch?

2 confirmed blood types and current and histrically negative antibody screens

120

What does MSBOS stand for and what is its purpose?

Maximum Surgical Blood Order Schedule- a guideline for physicians to assist them in ordering blood for surgeries.

121

Blood donor and recipient samples used in crossmatching must be retained for a minimum of _____ days following transfusion.

a. 2

b. 7

c. 10

d. 14

b. 7

122

Approximately what percentage of significant antibodies in patients' sera will be detected by adequate antibody screening procedures?

a. 28%

b. 50%

c. 73%

d. 99%

d. 99%

123

True or False:

Besides a final check of ABO compatibility between donor and recipient, another function of the crossmatch test is that is may detect the presence of an antibody in the patient's serum that will react with antigens on the donor RBCs but that was not detected in antibody screening because the corresponding antigen was lacking from the screening cells.

TRUE

124

When crossmatching blood for a patient with anti-Fyb , which of the following would be an appropriate unite of blood to use?

a. Fy (a-b+)

b. Fy (a+b+)

c. Fy (a+b-)

c. Fy (a+b-)

125

When testing donor unites for the Fya antigen, which of the following would be the most appropriate positive control?

a. Fy (a-b+)

b. Fy (a+b+)

c. Fy (a+b-)

b. Fy (a+b+)

126

The crossmatch will do each of the following EXCEPT:

a. detect the antibody to hepatitis

b. detect the antigen on the donor red cells for which the recipient has the corresponding antibody

c. detect ABO-incompatilibilty between the donor and the recipient

a. detect the antibody to hepatitis

127

What is the most common cause of ABO-incompatible transfusion?

Mistaken identity-

  • giving blood to the wrong person

or

  • giving the wrong blood to the intended recipient

128

Compatible or incompatible:

Recipient: O+ IAT neg

Donor: O+

Compatible

129

Compatible or incompatible:

Recipient: A+ IAT negative

Donor: O+

Compatible

130

Compatible or incompatible:

Recipient: O- IAT positive Anti-D in serum

Donor: O-

Compatible

131

Compatible or incompatible:

Recipient: A+ IAT negative

Donor: AB+

Incompatible

132

Compatible or incompatible:

Recipient: A+, IAT positive, Anti-C in serum

Donor: O+ C-positive

Incompatible

133

Pretransfusion testing:

a. proves that the donor's plasma is free of all irregular antibodies

b. detects most irregular antibodies on the donor's RBCs that are reactive with patient's serum

c. detect most errors in the ABO groupings

d. ensures complete safety of the transfusion

c. detect most errors in the ABO groupings

134

Which is not true of rouleaux formation?

a. it is a stacking of RBCs to form aggregates

b. it can usually be dispersed by adding saline

c. it can appear as an ABO incompatibility

d. it cannot cause a false-positive immediate spin crossmatch

d. it cannot cause a false-positive immediate spin crossmatch

135

What type of blood should be given in an emergency transfusion when there is no time to type the recipient's sample?

a. O Rh0 (D)-negative, whole blood

b. O Rh0 (D)-positive, whole blood

c. O Rh0 (D)-positive, packed cells

d. O Rh0 (D)-negative, packed cells

 

d. O Rh0 (D)-negative, packed cells

136

A patient developed an anti-Jka antibody 5 years ago. The antibody screen is currently negative. To obtain suitable blood for transfusion, which procedures apply?

a. Type the patient for the Jkb antigen as an added part to the crossmatch procedure

b. crossmatch random donors with the patient's serum, and release the compatible units for transfusion to the patient

c. type the patient and donor units for the Jka antigen, and then crossmatch the Jka negative units with the patient serum

d. Computer-crossmatch Jka negative donor units

c. type the patient and donor units for the Jka antigen, and then crossmatch the Jka negative units with the patient serum

137

A 26-year-old B Rh0 (D)-negative female patient requires a transfusion. No B Rh0 (D)-negative donor units are available. Which should be chosen for transfusion?

a. B Rh0 D-positive RBCs

b. O Rh0 D-negative RBCs

c. AB Rh0 D-negative RBCs

d. A Rh0 D-negative RBCs

b. O Rh0 D-negative RBCs

138

Having checked the patient's prior history after having received the specimen and request, you:

a. do not have to repeat the ABO and Rh if the name and hospital number agree

b. Do not have to repeat the IAT if the previous IAT was negative

c. Have to perform a crossmatch only if one has not been done within the last 2 weeks

d. Have to compare the results of your ABO, Rh, and IAT with the previous results

d. Have to compare the results of your ABO, Rh, and IAT with the previous results

139

The purpose of the immediate spin crossmatch is to:

a. ensure survival of transfused RBCs

b. determine ABO compatibility between donor and recipient

c. detect cold-reacting unexpected antibodies

d. meet computer crossmatch requirements

b. determine ABO compatibility between donor and recipient

140

Which does not represent requirements set forth by the AABB for the performance of a computer crossmatch?

A. cromputer system must be validated on-site

B. Recipient antibody screen must be positive

C. 2 determination of the recipient ABO and Rh must be performed

D. Computer system must have logic

B. Recipient antibody screen must be positive

141

You have just received a requiest and sample for pretransfusion testing. Which is the most appropriate to do first?

A. perform the ABO and Rh typing

B. complete the crossmatch

C. perform the IAT to see if the patient is going to be a problem

D. Check the records for prior type and screen results on the patient

D. Check the records for prior type and screen results on the patient

142

Blood donor and recipient samples used in crossmatching must be stored for a minimum of how many days following transfusion?

A. 2

B. 5

C. 7

D. 10

C. 7

143

Which is true regarding compatibility testing for the infant younger than 4 months old?

a. a DAT is required

b. A crossmatch is not needed with the infant's blood when unexpected antibodies are present

c. maternal serum cannot be used for antibody detection

d. to determine the infant's ABO group, RBCs must be tested with reagent anti-A, anti-B, and anti-A,B

b. A crossmatch is not needed with the infant's blood when unexpected antibodies are present

144

A nurse just called to request additional RBC units for a patient for whom you performed compatibility testing 4 days ago. She would like you to use the original specimen, as you keep it for 7 days anyway. Your most appropriate course of action would be to:

a. check to see if there is enough of the original specimen

b. perform the compatiblity testing on the original specimen

c. requiest more information in case the patient has developed a clinically significant unexpected antibody

d. indicate that a new specimen is necessary because the patient has been recently transfused

d. indicate that a new specimen is necessary because the patient has been recently transfused

145

A crossmatch is positive at AHG phase with polyspecific AHG reagent but is negative with monospecific anti-IgG AHG reagent. This may indicate the antibody:

a. is a weak anti-D

b. is a clinically insignificant Lewis antibody

c. can cause decreased survival of transfused RBCs

d. is a Duffy antibody

b. is a clinically insignificant Lewis antibody

146

The emergency room requests 6 units of packed RBCs for a trauma patient prior to collection of the patient's specimen. The most appropriate course of action is to:

a. release group O RBCs to ER with trauma patient identification on each unit sent

b. refuse to release units until you get a patient sample

c. indicate necessity for signed patient waiver for incomplete pretransfusion testing

d. explain need of patient's ABO group prior to issuing blood.

a. release group O RBCs to ER with trauma patient identification on each unit sent

147

Which is not an example of the most common form of error associated with fatal transfusion reactions?

a. phlebotomist labels patient A tubes with Patient B information

b. Technologist enters results of patient A with patient B information

c. Wrong RBC unit is tagged for transfusion

d. antibody below detectable levels during pretransfustion testing

d. antibody below detectable levels during pretransfustion testing