Compatibility testing and cross-matching is done before the blood transfusion. This will ensure that there is no incompatible reaction on blood transfusion. Therefore this will not test for any reaction which occurred years ago.
Blood grouping and typing may be done anytime and will tell you your blood group. This will not detect an incompatible blood transfusion years ago.
Immediately after an incompatible blood transfusion tests may be done to know why there was a reaction. For this both the donor blood and your blood needs to be present. However after years of the suspected reaction not much can be done. Please ask your doctor and see the notes in your clinical chart to know whether there was any blood transfusion reaction.
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Yes I am saying that after 4 years there will be no evidence of the incompatible blood that was transfused. You may have developed new antibodies due to the incompatible blood transfusion. For this please consult a hematologist in your location.
Incompatible blood will last for only a few hours.