If you know your patient is Rh Positive, Give Positive! Even if you have only one Rh type done.
Many probably think using Rh Negative blood will make it easier to find antigen negative blood when needed, for example in patients with anti-E. Truth is, E-negative blood is easy to find (70%) in Rh Positive units too!
Let’s say you’ve finished a patient’s ABO, Rh typing, and you know they are a group A Rh Positive, but WHOOPS… they have a positive Antibody Detection Test (Screen)… and the physician calls and wants Blood NOW! EMERGENCY! You send an O Rh Negative right? WRONG! Why not send an A Rh Positive?! The O Rh Negative is our “go to” in Emergency Release, but it is not magically safer when it comes to alloantibodies. ABO specific types are preferred!
We all know we give O Rh Negative to women of childbearing age because we don’t want them to make an Anti-D; that could cause some nasty hemolytic disease of the fetus and newborn (HDFN). However, the risk of HDFN in men is like… zilch (these guys aren’t getting pregnant any time soon)! We can safely consider switching to Rh Positive RBCs. If an Rh Negative male does make anti-D after being transfused Rh Positive blood, they will receive Rh Negative RBCs from that point forward.
Going along with the guys, women >50 years of age are unlikely to become pregnant so the risk of HDFN is minimal. If there is abundant need for emergent RBCs, consider using Rh Positive.