What is the purpose of crossmatching blood with the patient order?

• A. To ensure compatibility and safety before transfusion.
• B. To check only patient's identity.
• C. To determine the cost of transfusion.
• D. To decide the isotonic solution to use.

Answer: (A)

Crossmatching a patient’s blood with the donor unit is done to verify compatibility before a transfusion. This test checks that the donor red blood cells will not be attacked by the patient’s antibodies and confirms ABO and Rh compatibility. By mixing the patient’s serum with the donor cells (and looking for a reaction), clinicians can detect antibodies that could cause an immune attack on the transfused cells. If the crossmatch is compatible, the transfusion is considered safe regarding immune reactions; if not, a different donor unit is chosen. This process is about safety and correct matching, not about patient identity, cost, or IV fluid choices.