cross-matching

Cross-matching or crossmatching is a test performed before a blood transfusion as part of blood compatibility testing. Normally, this involves adding the recipient's blood plasma to a sample of the donor's red blood cells. If the blood is incompatible, the antibodies in the recipient's plasma will bind to antigens on the donor red blood cells. This antibody-antigen reaction can be detected through visible clumping or destruction of the red blood cells, or by reaction with anti-human globulin. Along with blood typing of the donor and recipient and screening for unexpected blood group antibodies, cross-matching is one of a series of steps in pre-transfusion testing. In some circumstances, an electronic cross-match can be performed by comparing records of the recipient's ABO and Rh blood type against that of the donor sample. In emergencies, blood may be issued before cross-matching is complete. Cross-matching is also used to determine compatibility between a donor and recipient in solid organ transplantation including heart/lung transplation. ==Types==

===Immediate-spin cross-matching=== Immediate-spin cross-matching (ISCM) is an abbreviated form of cross-matching that is faster, but less sensitive; its primary use is to detect a mismatch between ABO blood types. It is an immediate test that involves combining the patient's serum and donor's red blood cells at room temperature, then centrifuging the sample and observing for agglutination or hemolysis. A lack of agglutination or hemolysis indicates a negative test reaction, or compatible match. ISCM is not appropriate in all circumstances; if the recipient's antibody screen is positive, or if they have had a positive antibody screen in the past, a full crossmatch is performed instead.