Question

1. For each of the following forward reactions state the significance of the result.

For example, a patient cell is tested with anti-B and gives a positive reaction. The significance is that this indicates the presence of the B antigen on the unknown red cell.

Typing serum reaction		Significance
anti-A	4+
anti-B	0
anti- A	0
anti-B	3+ mf

Answer 1

When recording results , a plu sign (+) is concidered positive, a zero( 0) is considered negative, and all reactions are graded on a scale of zero ( negative ) to most positively reactive (4+).

For example, if the patient is blood type A , then the forward results will have a 3 to 4 plus positive result with the anti-A and a negative result with anti-B. The reverse typing should be the opposite of the forward typing.A cells will be negative and the B cells will be 2 to 4 plus positive.

Refer the chart below for the reactions of each blood group

FORWARDTYPING

	Anti -A	Anti-B
Group A	3-4 +	0
Group B	0	3-4+
Group AB	3-4+	3-4+
Group O	0	0

REVERSE TYPING

	A cells	B cells
Group A	0	2-4+
Group B	2-4+	0
Group AB	0	0
Group O	2-4+	2-4+

Forward typing uses patients red blood cells.All blood cells contains antigens that are specific to patients' blood type.When antibody Anti A / Anti B reagent is added to patients red blood cells ,the antigens on the cells will cause the cells to react with antibodies. For example, patient has blood typeA ,patient's red blood cells will clump with antibody A / Anti- A.

Typing	Serum reaction	Significance
anti -A	4+	Reaction is positive.Indicates presence of antigen A in patient cells
anti-B	0	0 means reaction is negative.So no antigen B in patient cells
anti -A	0	0 means reaction is negative .So no antibgen A in patient cells
anti-B	3+ mf	Reaction is positive. So indicates the presence of antigen B in patients cells. Mixed field (mf) reaction defines the presence of strongly agglutinated cell clumps admixed with unagglutinated cells.Mixed field agglutination describes the presence of two populations of red cells.Retest to rule out ABO discrepency.