Medicolegal assessment of blood transfusion errors--an interdisciplinary challenge

Given a current total incidence of erroneously administered blood transfusions of 1:12,000-1:36,000 (AB0 incompatible 1:38,000), the percentage of lethal outcomes ranges between 2 and 5%; i.e. the sole fact of an erroneous transfusion does not mandatorily result in a causal connection with lethal outcome, which can give rise to problems in the medicolegal assessment. We report on the conception and results of a novel interdisciplinary approach to assess the lethal significance of blood transfusion errors. Besides autopsy, histological investigation and immunohistochemical detection of AB0 incompatible foreign red blood cells in autopsy specimens, transfusion medicine investigations offer the opportunity to assess several immunohaematologic features. We assessed the immunohaematologic gel card ("microcolumn") technique for suitability in the forensic assessment of an AB0 incompatible transfusion incident in a septic patient, who had had no history of previous blood transfusions, with lethal outcome. After such an erroneous transfusion had been simulated in vitro, pre-transfusion and cadaver patient blood samples (p.m. interval: 3 days) were analysed. Amongst other things, IgG-loaded erythrocytes were detected in pre- and post-transfusion samples; the presence of irregular antibodies directed against blood group antigens and anti-A or anti-B isoagglutinins, respectively, especially in the pre-transfusion sample was ruled out. Besides the demonstration of AB0 incompatible red blood cells in the cadaver blood sample, blood group incompatibilities other than AB0 were excluded. With regard to the cause of death, in synopsis with autopsy findings and clinical symptoms, the results did not allow for a final discrimination between the impact of the pre-existing septic inflammatory response syndrome and sepsis, respectively, and potential lethal effects of a (haemolytic) transfusion reaction. Besides pre- and post-transfusion compatibility testing in clinical transfusion medicine as required by German National Guidelines, the reported immunohaematologic investigations offer an important supportive tool for the forensic assessment of lethal erroneous transfusions and investigation of blood samples of survivors of transfusion incidents as well. Besides established morphological techniques, they allow for a certain evaluation of the pathophysiological impact of transfusion incidents as well as a diversified assessment of immunohaematologic features beyond the AB0 system.