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 Redstone to evaluate individual belief in respect to blood among Jehovah's Witnesses. The study showed that 12% were willing to accept transfusion therapy forbidden by Jehovah's Witness doctrine. One peer-reviewed study examining medical records indicated a similar percentage of Jehovah's Witnesses willing to accept blood transfusions for their children. Young adults also showed a willingness to accept blood transfusions. In another study, Jehovah's Witness patients presented for labor and delivery showed a willingness to accept some form of blood or blood products. Of these patients, 10 percent accepted whole blood transfusion. Watch Tower publications have noted that within religions, the