Question

Miss Ima Crohns, age 45, is admitted to the ER with gastrointestinal discomfort. The physician wishes to do exploratory surgery and orders a Type and Screen for her surgery later that day. You receive her properly labeled specimen and proceed with the type and screen testing. Here are your findings:

Forward Grouping				Reverse Grouping		Gel Screen
>A	>B	>D	D Control	A1 Cells	B Cells	SCI	SCII	SCIII
4+	2+	4+	0	0	4+	0	0	0

1. What is your interpretation of the forward grouping?

2.What is your interpretation of the reverse grouping?

3. What type of discrepancy do you suspect?

4. Name two ways to resolve the discrepancy

Answer 1

1. The forward gruping of the cells is indicative of the antigen present in the blood. According to the data, antigen A, B and D are present in the blood as per the forward grouping indicating that the blood type could be AB+ve. The grade appearance of B antigen is 2+ indicating that there were small or medium clumps of agglutinated cells through the tube/column. The 4+ grade appearance of A and D indicates that a well defined band of agglutinated RBCs.

2. The reverse grouping is suggestive of the antibody present in the serum. According to the data, there was no agglutination in A1 cells and a well defined band of agglutination (grade appearance 4+) in B cells. This suggests that the patient is A+ve.

3. The agglutination found in B in forward grouping could be a false positive as the grade appearance is also low. This could be due to heavy coating of the patient's RBCs with immunglobulins (abnormal concentration of serum proteins). The presence of infused macromolecular solutions in the serum or plasma may also cause non-specific agglutination.

4. The discrepancy can be resolved by performing the forward and reverse grouping again. A DAT (Direct Antiglobulin Test) can be performed. It detecs antibodies attached to the RBCs circulating in the bloodstream.