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
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