3. Lab-Introduction to ABO & Rh

What are the two types of typing used in ABO testing?

Forward typing and reverse typing.

What does forward typing test?

It tests the patient’s red cells using known antibodies to determine what antigens are present.

What does reverse typing test?

It tests the patient’s plasma using known red cells to determine what antibodies are present.

What happens if forward and reverse typing results do not match?

An ABO discrepancy is identified, and blood group cannot be assigned until both results agree.

What must you check before any testing begins?

Patient history, specimen verification, and proper labeling.

What is the requirement for tube labeling?

All tubes must be labeled before adding any specimen or reagents.

What is the consequence of adding cells before reagents?

It could invalidate the results.

How should the tubes be arranged during testing?

In a consistent order to prevent mix-ups.

What reagent is used for Rh (D) typing?

Anti-D reagent.

What must accompany the Rh reagent?

An Rh control, which must be negative for the test to be valid.

Why is centrifugation important before reading tubes?

It ensures the tubes are properly balanced and labeled for accurate results.

How is agglutination graded?

From 0 (smooth suspension, no clumps) to 4+ (strongest agglutination).

What should you do immediately after recording results?

Match the tube to the corresponding box on the worksheet and initial the results.

What is an ABO discrepancy and how should it be handled?

A mismatch between forward and reverse typing; it must be identified, documented, and resolved prior to reporting.

How should ABO/Rh results be reported?

In words only, such as A Positive or B Negative, not using symbols.

What action should be taken if a sample is mislabeled?

Stop testing, document the issue, and indicate corrective action required.

What are the components of blood group antigens for blood types A, B, AB, and O?

A antigen for A, B antigen for B, both for AB, none for O.

What antibodies are present in the plasma for blood types A, B, AB, and O?

Anti-B for A, Anti-A for B, both Anti-A and Anti-B for AB, none for O.

What does agglutination indicate during forward typing?

The presence of an antigen on the patient's red cells.

What does agglutination indicate during reverse typing?

The presence of an antibody in the patient’s plasma.

What must you ensure before centrifuging the tubes?

That they are all properly labeled and balanced.

What is the order of addition for testing?

Plasma or antisera first, followed by the red cell suspension.

What are the known antibodies used in forward typing testing?

Anti-A and Anti-B.

What types of cells are used in reverse typing testing?

A1 cells and B cells.

What is the consequence of performing tests on mislabeled samples?

It is considered a critical error and could lead to a significant deduction of points.

What should you do to prepare a 3–5% red cell suspension?

Wash red cells and prepare the suspension for forward typing.

What is the significance of using EDTA tubes?

They contain an anticoagulant that preserves the blood specimen for testing.

In the bench interpretation challenge, what is the primary task?

Interpret reactions on pre-set tube racks to determine ABO and Rh type.

What should be done with tubes before reading reactions?

They should not be shaken or resuspended prior to reading.