Blood Bank Chapter 8-10

How many units of red blood cells are required to raise the hematocrit of a 70kg nonbleeding adult man from 24% to 30%?

2

If the recipient was transfused within the last 3 months, how long from the time of collection can a sample be used for crossmatch?

3 days

If not store in a monitored refrigerator, how long can RBC units remain outside the transfusion service to allow reissue?

30 minutes

How long following transfusion must the recipient's sample be stored?

7 days

A recipient is AB negative, supply for the type specific is depleted. Best choice substitution is

A neg

A donor unit with a positive DAT would cause reactions at what phase of the crossmatch?

AHG

DAT results is as follows: Polyspecific AHG 1+ Anti IgG Neg CC 3+ The cause is

Anti C3d

A patient's serum reacted weakly with all panel cells tested at the antiglobulin phase using LISS and were not enhanced using PEG. The autocontrol was negative. Ficin-treated panel cells were nonreactive. What is the most likely specificity of the antibody?

Anti-Ch

Select the antibody where DTT would be usedful in the identification investigation

Anti-Kp(b)

In the process of identifying an antibody, the technologist observed 2+ reactions with 3 of the 10 cells in a panel at the immediate-spin phase. These reactions disappeared following incubation at 37C and the antihuman globulin phase of testing. What is the most likely responsible antibody?

Anti-Le(a)

An antibody was detected at immediate-spin and 37C that appeared to have anti-Le(b) specificity. To confirm the antibody identity and determine if there were other antibodies in the serum, a Lewis neutralization technique was performed. Patient serum + Lewis substance = 0 Patient serum + saline control = 1 Neutralized serum + Fy(a+b+) red cell = 0 What conclusion can be made from these results?

Anti-Le(b) is confirmed

An example of a cold alloantibody includes:

Anti-M

An antibody that is not produced against a low-incidence antigen?

Anti-Vel

A recipient is group O with the following phenotype: D+ C+ c- E+ e+. What alloantibody could this patient produce?

Anti-c

When should anti-Sd(a) be suspected?

Antibody reacts with most panel cells and are mixed field and refractile microscopically

If all antibody identification panel cells were reactive at the same strength at the antihuman globulin phase, no negative reactions were observed, and the autocontrol was negative, what antibody should be suspected?

Antibody to a high-frequency antigen

Antibody screening cells are positive at the antihuman globulin phase of testing. What is the first step in this investigation?

Check transfusion and pregnancy history

Why is a recipient's antibody screen performed as a component of compatibility testing?

Detects red cell alloantibodies

Why is a recipient's antibody screening performed as a component of compatibility testing?

Detects red cell alloantibodies

What is the most important concern when trying to identify antibodies in a patient with a warm autoantibody?

Determining whether there are underlying alloantibodies

Which of the following tests is not included in routine compatibility testing?

Direct antiglobulin test

What are the two components of the major crossmatch?

Donor red cells and recipient serum

True or false: A crossmatch demonstrating a 2+ agglutination is interpreted as compatible

False

What is the typical specificity of cold autoantibodies?

I

What is the immuglobulin class of antibodies detected in the immediate-spin crossmatch?

IgM

What is the immunoglobulin class of antibodies detected in the immediate spin crossmatch?

IgM

A group O patient was crossmatched with group B RBC's. What phase of the crossmatch will first detect this incompatibility?

Immediate spin

A group O patient was crossmatched with group B red cells. What phase of crossmatch will first detect this incompatibility?

Immediate-spin

Why is the agglutination phase important in the interpretation of the antibody screen or antibody identification panel?

Indicates the class of the antibody

Why is the agglutination reaction phase important in the interpreting of the antibody screen or antibody identification?

Indicates the class of the antibody

Anti-Fy(a) was identified in a patient's serum. The patient's red cells phenotyped as Fy(a)+ using commercial anti-sera. What is the next step?

Investigate a recent transfusion history

Anti-D, anti-K, and anti-Jka are the antibodies that are tentatively identified on a panel after initially ruling out on negative cells. What selected cell from another panel should be chosen to confirm the presence of anti-K?

K+, D-, Jk(a-)

An antigen not commonly used on screening cells?

Kp(a)

A medication most likely to be the cause of production of autoantibodies?

Methyldopa

When is the immediate-spin or abbreviated crossmatch an acceptable procedure for the recipient?

No prior or existing clinically significant antibodies

When type O blood is not available for transfusion for a type O recipient, what is the next alternative?

None

A blood product that requires a crossmatch before issuing?

Patient RBC's and granulocyte concentrates that have more than 2 mL of RBC's

What type of red cells is used in an autoadsorption to remove antibody from the serum?

Patient red cells

What does a negative reaction in the MTS Gel Test look like in the gel card?

Pellet of cells at the bottom of the column

What does a negative reaction in the gel test look like in the gel card?

Pellet of cells at the bottom of the column

If an anti-I is suspected in a patient's sample that requires a transfusion, the most acceptable course of action is to:

Perform the prewarm technique

A smooth layer of cells in the bottom of the well is interestd as a?an _________ reaction when solid-phase testing method is completed for the antiglobulin test

Positive

Situations that can be found in a classic case of autoimmune hemolytic anemia

Positive DAT, false positive phenotyping, crossmatch incompatibility at AHG

What situations can be found in a classic case of autoimmune hemolytic anemia?

Positive direct antiglobuin test, false positive Fy(a) phenotyping, crossmatch incompatibility at antihuman globulin

A smooth layer of cells in the bottom of the well is interpreted as a/an __________________ reaction with the solid-phase red

Postitive

Compatibility procedures will not address....

Preventing formation of all red cell antibodies

What is a characteristic of Rh system antibodies?

Reactions that are enhanced with enzymes

If an emergency exists and there is not enough time to perform a crossmatch for red cells, what is the correct procedure?

Release group O- RBC units

What is the next step in the investigation of a positive DAT test with polyspecific antihuman globulin reagent?

Repeat the direct antiglobulin test using monospecific anti-IgG and anti-C3

What is the next step in the investigation of a positive direct antiglobulin test with polyspecific antihuman globulin reagant?

Repeat the direct antiglobulin test using monospecific anti-IgG and anti-C3 reagents

Why are proteolytic enzymes not used in routine sceening for antibodies?

Some antigens are destroyed by enzymes

Why are proteolytic enzymes not used in the routine screening for antibodies?

Some antigens are destroyed by enzymes, which would cause the antibodies to be missed

Description of the elution technique:

Technique that disassociates IgG antibodies from red cells for further identification

Random access is an important feature in selecting an automated instrument. What is random access?

The ability to accommodate STAT testing

In an antibody identification panel, only one red cell was negative at the antihuman globulin phase. On ruling out and matching the pattern, an anti-k was identified. What further testing is necessary to confirm the antibody?

Two more k-negative cells should be tested

What can be done to increase the sensitivity of the antibody screen in a compatibility test?

Use an enhancement such as LISS or PEG, extend the incubation time, or increase the serum-to-cell ratio

An autoadsorption may be performed to investigate underlying autoantibodies. When is this procedure acceptable?

When the patient has not been recently transfused

A sample must be labeled ______________ for compatibility testing

at bed side

The use of the electronic (computer) crossmatch is restricted to recipients who

do not have a clinically significant antibody

A sample must be ________ when collected for compatibility testing

labeled at the patient's bedside

A compatible crossmatch is

negative at AHG, positive with check cells

A smooth layer of cells in the bottom of the well is interpreted as a/an ____________ reaction when the solid phase?

positive

High-titer, low-avidity antibodies typically:

react with antigens of high frequency in the population