Blood transfusion of transfusing uncrossmatched blood, O-negative blood is used, followed by crossmatch as soon as possible. O-negative is also used for children and women of childbearing age. It is preferable for the laboratory to obtain a pre-transfusion sample in these cases so a type and screen can be performed to determine the actual blood group of the patient and to check for alloantibodies. This chart shows possible matches in blood transfusion between donor and receiver using ABO and Rh system. In the same way that the safety of pharmaceutical products is overseen by pharmacovigilance, the safety of blood and blood products
Blood type or anti-B antibodies. Typically, blood type tests are performed through addition of a blood sample to a solution containing antibodies corresponding to each antigen. The presence of an antigen on the surface of the blood cells is indicated by agglutination. An alternative system for blood type determination involving no antibodies was developed in 2017 at Imperial College London which makes use of paramagnetic molecularly imprinted polymer nanoparticles with affinity for specific blood antigens. In these tests, rather than agglutination, a positive result is indicated by decolorization as red blood cells which bind to the nanoparticles are pulled toward a magnet