Packed red blood cells Rh type, specifically the phenotype, and the "screen" refers to testing for atypical antibodies that might cause transfusion problems. The typing and screening are also performed on donor blood. The blood groups represent antigens on the surface of the red blood cells which might react with antibodies in the recipient. The ABO blood group system has four basic phenotypes: O, A, B, and AB. In the former Soviet Union these were called I, II, III, and IV, respectively. There are two important antigens in the system: A and B. Red cells without A or B are called type O, and
Jehovah's Witnesses and blood transfusions place patients at heightened risk for reduced long-term survival." The study also stated that "Survival estimates of Witnesses were 86%, 69%, 51%, and 34% at 5, 10, 15, and 20 years after surgery, respectively, vs 74%, 53%, 35%, and 23% among non-Witnesses who received transfusions." Bloodless medical and surgical techniques have limitations, and surgeons say the use of various allogeneic blood products and pre-operative autologous blood transfusion are appropriate standards of care for certain patient presentations. The Watch Tower Society states that in medical emergencies where blood transfusions seem to be the only available way to save a life, Jehovah's