Question: what is the difference between rh null and rh negative blood?
Answer: O negative red blood cells lack the A and B antigens (hence, group O) and also the Rh(D) antigen. Rh null blood lacks all the antigens in the Rh group, such as D, C, c, E, e and others. The Rh null red cells can still be positive for A or B antigens, the presence or absence determines their ABO blood type.