Determination of Both Fetus’ and Mother's Blood Type from an Autopsy Case Immersed in Formalin for Over 50 Years

A female fetus which had been immersed in formalin for more than 50 years was found in Japan. Because no liquid blood could be obtained, we tried to use immunohistochemistry (IHC) methods to tissue samples obtained at autopsy to identify both the fetal and mother's blood type. We detected B antigens on endothelial cells in paraffin sections of the fetal organs. Furthermore, we observed both anti‐A‐ and anti‐B‐positive red blood cells in the intervillous space, which is indicative of the mother's blood type. To our knowledge, this is the first case report on determining the blood type of both the fetus and the mother from tissue immersed in formalin for such a long time. The results suggest that IHC is valuable for the determination of ABO blood type in circumstances of long postmortem duration and unfavorable storage conditions.