Packed red blood cells do not have an antibody, since the greatest risk of Rh incompatible blood is to current or future pregnancies. For RBCs, type O negative blood is considered a "universal donor" as recipients with types A, B, or AB can almost always receive O negative blood safely. Type AB positive is considered a "universal recipient" because they can receive the other ABO/Rh types safely. These are not truly universal, as other red cell antigens can further complicate transfusions. There are many other human blood group systems and most of them are only rarely associated with transfusion problems. A screening test is
Jehovah's Witnesses and blood transfusions on blood transfusions has come from both members and non-members. A group of dissident Witnesses known as Associated Jehovah's Witnesses for Reform on Blood (AJWRB) states that there is no biblical basis for the prohibition of blood transfusions and seeks to have some policies changed. In a series of articles in the "Journal of Medical Ethics" US neurologist Osamu Muramoto, who is a medical adviser to the AJWRB, has raised issues including what he claims is coercion to refuse transfusions, doctrinal inconsistency, selective use of information by the Watch Tower Society to exaggerate the dangers of transfusions and the use