Final answer:
Blood bank technicians must confirm blood type compatibility through pretransfusion testing, including the use of commercially prepared antibodies and a cross-match assay, before considering two units of packed cells available for client B.
Step-by-step explanation:
To determine the availability of two units of packed cells for client B, blood bank staff must first perform pretransfusion blood testing to ensure compatibility between the donor blood and the recipient's blood. This starts with using commercially prepared antibodies to confirm the presence of A, B, and Rh antigens in the donor blood, as well as testing the patient's blood type with the same antibodies.
If a patient's blood agglutinates when mixed with anti-B serum, it indicates the presence of B antigens, meaning the patient has either type B blood (possible B-positive or B-negative). A cross-match assay is then conducted which involves mixing the donor's red blood cells with the recipient's serum to ensure no adverse reaction occurs, verifying compatibility.
In scenarios where the blood bank has successfully identified the blood type of the donor and patient, and the cross-match assay is compatible with no agglutination observed, the two units of packed cells can be considered available for the client.