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Background: Prehospital low-titer group O whole blood (LTOWB) used for patients with life-threatening hemorrhage is often RhD positive. The most important complication following RhD alloimmunization is hemolytic disease of the fetus and newborn (HDFN). Preceding clinical use of RhD positive LTOWB, we estimated the risk of HDFN due to LTOWB prehospital transfusion in the Finnish population., Study Design and Methods: We collected data on prehospital transfusions in Tampere and Helsinki University Hospital areas. Using the mean of reported alloimmunization rates in trauma studies (24%) and a higher reported rate representing trauma patients of 13-50 years old (42.7%), we estimated the risk of HDFN and extrapolated it to the whole of Finland., Results: We estimated that in Finland, with the current prehospital transfusion rate we would see 1-3 cases of severe HDFN due to prehospital LTOWB transfusions every 10 years, and fetal death due to HDFN caused by LTOWB transfusion less than once in 100 years., Discussion: The estimated risk of serious HDFN due to prehospital LTOWB transfusion in the Finnish population is similar to previous estimates. As Finland routinely screens expectant mothers for red blood cell antibodies and as the contemporary treatment of HDFN is very effective, we support the prehospital use of RhD positive LTOWB in all patient groups., (© 2024 The Authors. Transfusion published by Wiley Periodicals LLC on behalf of AABB.)

We present new genetic evidence obtained from population studies on Finns and from the studies on Finnish blood donors as well as their selected families using an antibody that defines a novel high-incidence Rh antigen MAR. Anti-MAR antibody shows an antithetical relationship to both anti-Cw and anti-Cx. The Rh antigens Cw (RH8) and, more strikingly, Cx (RH9) have each an exceptionally high frequency in Finns. Our studies on their genetic relationship indicate that the three antigens Cw, Cx and MAR behave as if being determined by alleles of the same Rh sub-system. Furthermore, we conclude that this sub-system manifests an inheritance pattern that is distinct from but analogous to that of the two well-known allelic sub-systems of C/c and E/e antigens.

Results from the Finnish interlaboratory proficiency testing programme in immunohaematology from 1976 to 1978 are reviewed. The results show excellent accuracy of ABO grouping (100% correct). In Rh (D) grouping the detection of weak D antigen (Du) offered difficulties due to insufficient methodology. Also a sample from a donor with a positive direct antiglobulin reaction created confusion in Rh (D) grouping. The screening of atypical antibodies in serum was performed excellently (100% correct); the antibody coating of red cells, however, was detected by only 83.3% of the participants. The accuracy of compatible crossmatches was good (on average 98.7% correct); the accuracy of incompatible crossmatches, however, was poorer (on average 88.1% correct). A considerable methodological variation in compatibility testing is suggested to be responsible for the poor performance. The performance of individual laboratories seemed to correlate with their position in the health service organization, and with the level of internal quality control procedures.

Analysis of 41 deaths from Rh(D) hemolytic disease (HDN) in Finland in the past 10 years revealed that 17 occurred in mothers immunized before anti-D IgG was available and three in mothers immunized by blood transfusion in earlier years. Nine deaths were related to loopholes in the anti-D program and could presumably have been prevented by ensuring that all eligible Rh-negative women received anti-D IgG after delivery and abortion. Six deaths were due to immunization during a first pregnancy after the 28th week and three to maternal immunization despite anti-D IgG. Immunization from these sources can only be reduced by anti-D IgG injected antenatally as well as postnatally, though the complete eradication of HDN seems to be beyond our grasp. Giving anti-D IgG to Rh-negative women after the birth of a Rh-positive infant or after an abortion has been common practice in Finland, the former since 1969 and the latter since 1971. Although anti-D prophylaxis has been very effective in reducing the incidence of Rh(D) hemolytic disease, new cases continue to occur. Since the prophylaxis fails to prevent perinatal mortality, we decided to discover how the mothers whose infants died from HDN had become immunized in the past 10 years.