Blood type: the patient's blood is tested to determine ABO and Rh antigen status.
These antigens will determine the type of antibodies the patient makes.
AB antibodies arise spontaneously, regardless of patient history.
Rh antibodies are formed only after exposure to an Rh antigen (previous transfusion, pregnancy)
Blood is screened: this involves mixing plasma with two or three commercial reagent ampules that contain the most clinically important RBC antigens implicated in hemolytic transfusion reactions.
If the results are negative, the patient can be safely transfused with ABO and Rh compatible blood since no clinically significant RBC antibodies are present.
If the patient has a positive screen, then antibody identification testing is required to identify the specific antibody. This involves the patient's plasma being placed onto a larger panel of reagents and results in identification of the RBC antibody in the patient's plasma.
a) Rh antibodies are formed spontaneously
b) Rh antibodies are formed after exposure to an Rh antigen
c) A positive screen is an indicator of RBC antibody presence
d) Negative screen results in the need for antibody identification testing
