Quick answer The client is B positive, but the red blood cell unit is labeled A positive. The ABO mismatch is incompatible, so the transfusion must not begin.
Why this is correct The client is B positive while the red-cell unit is A positive. This ABO mismatch is incompatible, so the transfusion must not begin.
Easy analogy or mental picture Treat the client record and blood-unit label as two halves of one identity check; every required identifier and compatibility element must agree.
Memory hook The A-positive red-cell unit is incompatible with the B-positive client record.
NCLEX decision rule Immediately before transfusion, compare the client, order, compatibility record, and unit label using the required independent check.
Why the other choices are wrong The unit identifier and verified client type are necessary checks, but the A-positive unit label is the incompatible element in this comparison.
References
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NCBI Bookshelf: Pretransfusion testing
Clinical situationBefore transfusion, the nurse compares the client record with the blood unit.
What the nurse should noticeThe client is B positive, but the red blood cell unit is labeled A positive. The ABO mismatch is incompatible, so the transfusion must not begin.
Transfer to practiceImmediately before transfusion, compare the client, order, compatibility record, and unit label using the required independent check.
ABO compatibility — Matching red-cell antigens with the recipient to prevent an acute hemolytic reaction.
Pretransfusion verification — The final identity and compatibility check completed before blood administration.