ABO blood group system B, and AB blood into type O. This is done by using glycosidase enzymes from specific bacteria to strip the blood group antigens from red blood cells. The removal of A and B antigens still does not address the problem of the Rh blood group antigen on the blood cells of Rh positive individuals, and so blood from Rh negative donors must be used. Patient trials will be conducted before the method can be relied on in live situations. Another approach to the blood antigen problem is the manufacture of artificial blood, which could act as a substitute in emergencies.
Blood transfusion by using blood type testing to identify a less scarce alternative. Jehovah's Witnesses object to blood transfusions due to their belief that blood is sacred. Although there are clinical situations where transfusion with red blood cells is the only clinically appropriate option, clinicians look at whether alternatives as feasible. This can be due to several reasons, such as patient safety, economic burden or scarcity of blood. Guidelines recommend blood transfusions should be reserved for patients with or at risk of cardiovascular instability due to the degree of their anaemia. In these cases parenteral iron is recommended. Thus far, there are