Unit 8: Problem-Solving in Immunohematology

What would you do if you have an IgM alloantibody and a negative autocontrol?

IgM = clinically insignificant

negative autocontrol = no autoantibody

give the patient XM compatible units

What would you do if you have an IgG alloantibody and a negative autocontrol?

IgG = clinically significant

negative autocontrol = no autoantibody

give the patient antigen-typed XM compatible units

What would you do if you have an IgG alloantibody and a negative autocontrol during an emergency transfusion?

IgG = clinically significant

negative autocontrol = no autoantibody

give the patient XM compatible units (O+ or O-) with emergency release form

In emergencies, women of child baring age should receive what type of blood?

O-

In emergencies, men and women over 45 should receive what type of blood?

O+

What would you do if you have an alloantibody and a positive autocontrol?

Check DAT:

IgG + = warm autoantibody or both allo and auto - perform elution

C3 + = cold autoantibody

give the patient antigen-typed XM compatible units

What are 3 reasons why a negative antibody screen would result in incompatible crossmatches at room temperature?

1. ABO incompatibility

2. Rouleaux

3. Polyagglutination

What are 2 reasons why a negative antibody screen would result in incompatible crossmatches at AHG phase?

1. positive DAT (autoantibody)

2. antibody to low frequency antigen that’s not normally screened

How do you differentiate rouleaux from true agglutination?

saline replacement technique

How many drops of saline to you add to the tubes being tested when performing a saline replacement technique?

2 drops

You are have a hard time determining if you are viewing true agglutination. After performing a saline replacement technique, the RBCs disperse. How would you interpret this?

negative (not true agglutination)

You are have a hard time determining if you are viewing true agglutination. After performing a saline replacement technique, the RBCs stay clumped together. How would you interpret this?

positive (true agglutination)

At which phase of testing is rouleaux not present and why?

AHG phase - rouleaux requires serum and you wash sample before AHG phase, removing any remaining serum

Cord blood specimens may have rouleaux formation caused by what contaminant?

Wharton’s jelly - protective connective tissue

Weak reactions at 37C and AHG phase of testing with titers of 64 or greater are seen in what type of antibodies?

high titer, low avidity (HTLA) antibodies

What IgG antibodies are clinically insignificant?

HTLA antibodies

What blood would you transfuse if a person has an HTLA antibody?

XM compatible blood (antigen negative blood not necessary due to clinical insignificance)

What is polyagglutination?

• A condition in which red blood cells agglutinate only in the presence of autoantibodies.

• A reaction where red blood cells are agglutinated by most adult human sera, but not with cord sera.

• A naturally occurring reaction between IgM alloantibodies and incompatible donor cells.

• An autoimmune condition where all blood group antigens are destroyed, resulting in spontaneous hemolysis.

A reaction where red blood cells are agglutinated by most adult human sera, but not with cord sera.

What would you do if you a patient exhibits polyagglutination?

give antigen-typed XM units that have been tested using Cord sera

What type of polyagglutination is associated with microbial enzymes changing the surface of RBCs during bacterial and viral infections?

acquired (T, Tk, Tn)

A weak front type and a strong back type is caused by a weak/missing (antigen/antibody).

antigen

Recent transfusion, ABO subgroups, and disease can cause what type of ABO discrepancy?

weak/missing antigen

Weak antigen reactions due to large amounts on non-ABO identical blood being transfused is known as:

chimerism

What subgroup front types as O and backtyypes as A?

Ael

How can you solve an ABO discrepancy due to additional antigen caused by a cold agglutinin?

cold auto-adsorption

A strong front type and a weak back type is caused by a weak/missing (antigen/antibody).

antibody

Disease and age of patient (newborns and elderly) can cause what type of ABO discrepancy?

weak/missing antibodies

What are 2 ways you can fix weak/missing antibody reactions?

1. use more patient plasma when back typing

2. perform front and back typing at 4C

Cold antibodies, rouleaux, recent transfusions, and pH can cause what type of ABO discrepancy?

additional antigens

Rouleaux, cold antibodies, alloantibodies, and anti-A1 can cause what type of ABO discrepancy?

additional antibodies

What are the first 2 steps you should take if you encounter an ABO discrepancy?

1. repeat testing with new cell suspension using different methodology (gel/tube)

2. review patient history

Which subgroup of A is the only subgroup that will react with Lectin reagent?

A1

What should you do if cold antibodies are causing ABO discrepancies?

prewarm screen

If you perform a prewarm screen that results in a positive, what units should you transfuse?

antigen-negative XM compatible units

If you perform a prewarm screen that results in a negative, what units should you transfuse?

XM compatible units (antigen-negative not required)