The term compatibility testing refers to a set of procedures requires before the blood is issued by the blood bank as being compatible. The pre-transfusion compatibility testing will confirm the ABO compatibility between the donor and the recipient & presence of clinically significant antibodies.
Cross matching is a part of compatibility testing. It is carried out to ensure that there are no antibodies present in the patient’s serum that will react with the donor cell when transfused.
Immediate spin method– In a clean dry test tube 2 drops of the recipient serum is taken & to this add 2 drops of donor red cell. The content is mixed well then they are centrifuged for 1 minute at 1000 rpm. The tube is examined for agglutination.
If agglutination is present then crossmatch is compatible. If agglutination negative the cell is washed well with saline & to this 1 drop of anti-human globulin is added. The tube is centrifuged & look for any agglutination. If there is no agglutination then the sample is declared compatible & fit for transfusion.