Central Maine Medical Center Leeds, Maine, United States
Background/Case Studies: In 2023, a new D-typing policy for women of childbearing potential, women under the age of 50, was implemented in a rural Maine hospital to better align with national guidelines. If the D-agglutination strength is less than 2+ on the Echo’s (Werfen, Norcross, GA) automated hemagglutinin method for anti-D4 or anti-D5 in a woman of childbearing potential, the sample is tested in tube. If immediate spin tube testing shows an agglutination strength of less than 2+ using D4 or D5, the D-antigen is reported as D-negative, the woman is a candidate for Rh immune globulin (RhIG), and the sample is sent to a reference laboratory for RHD genotyping. Under the previous policy, a D-agglutination strength of 1+ or greater on the Echo or in tube was considered D-positive. Males and women over the age of 50 with a D-agglutination strength of 1+ on the Echo or in tube are reported as D-positive. The change in policy was made to better comply with the 2015 Joint Statement by AABB and CAP recommending RHD genotyping for females of childbearing potential who demonstrate weak or no agglutination with anti-D typing reagents. (Web Resource 1).
Study
Design/Methods: A retrospective study was completed reviewing all Blood Bank sendout testing from 2013-2025. A total of 10 RHD genotypes were sent from 2022 to 2025. One sample was sent in 2022 prior to the policy change while 9 were sent from January 2023 to April 2025. No samples were sent for RHD genotyping from 2013-2021.
Results/Findings: Of the ten women meeting criteria for RHD genotyping, all demonstrated genotypes warranting RhIG administration. There is little known about the three predicted weak D phenotype’s ability to make alloanti-D, therefore they were treated as D-negative. No cases of anti-D alloimmunization or hemolytic disease of the fetus and newborn were reported. Conclusions: Increasing the minimum reaction strength to report women of childbearing potential as D-positive with implementation of RHD genotyping successfully identified patients requiring RhIG and D-negative red blood cells. The results obtained in this study supports broader adoption of genotyping studies even in rural settings to better treat and care for women of childbearing potential.
