We perform Type & Screens on OB patients. If the antibody screen is positive on an Rh Negative OB patient with a RhIG administration date within the previous 12 weeks, we perform Ortho's short antibody panel. When performing the short panel a D-antigen positive cell must be run for the positive control. If the D-antigen positive cell reacts >2+ it must be further investigated for active (alloimmunization) Anti-D. RhIG does not produce strong reactions and therefore Blood Bank staff must practice caution when "assuming" passive Anti-D due the RhIG administration. A strong indicator for Techs is the reaction strength noted for the D-antigen positive cell. Furthermore, reactions >2+ should have an antibody titer performed to aid in interpretation of passive Anti-D versus active Anti-D. RhIG produces a titer of 1:4 or less. It would be rare for RhIG to produce a titer greater than 1:4. Active Anti-D generally produces a much higher titer, therefore distinguishing it from passive Anti-D. Interpretation issues should involve consultation with the Medical Director or a pathologist.
We perform Type & Screens on OB patients. If the antibody screen is positive on an Rh Negative OB patient with a RhIG administration date within the previous 12 weeks, we perform Ortho's short antibody panel. When performing the short panel a D-antigen positive cell must be run for the positive control. If the D-antigen positive cell reacts >2+ it must be further investigated for active (alloimmunization) Anti-D. RhIG does not produce strong reactions and therefore Blood Bank staff must practice caution when "assuming" passive Anti-D due the RhIG administration. A strong indicator for Techs is the reaction strength noted for the D-antigen positive cell. Furthermore, reactions >2+ should have an antibody titer performed to aid in interpretation of passive Anti-D versus active Anti-D. RhIG produces a titer of 1:4 or less. It would be rare for RhIG to produce a titer greater than 1:4. Active Anti-D generally produces a much higher titer, therefore distinguishing it from passive Anti-D. Interpretation issues should involve consultation with the Medical Director or a pathologist.