Could Postmortem Hemorrhage Occur in the Brain?

The aim of this study was to explore whether postmortem hemorrhage can occur in brain tissue using rabbit models.The rabbits killed by air embolism were randomly divided into the horizontal-position group and the upside-down group. Autopsy was performed after 48 hours, and the brains were investigated with macroscopic assessment and histologic examination.Macroscopically, congestion of vessels on the surface of the brain was identified in all the subjects in both groups. Microscopically, the presence of multifocal extravascular red blood cell aggregation was observed in brain parenchyma and subarachnoid space in the upside-down group. In contrast, no leakage of extravascular red blood cells was observed in the brain parenchyma and the subarachnoid space in the horizontal-position group.Hypostatic and leakage bleeding can occur in sites of subarachnoid space and brain parenchyma of rabbits after death by nonforce with a certain period and certain position of the placement. This type of hemorrhage is challenging to differentiate from traumatic hemorrhage in pathologic practice. To avoid misdiagnosis, the clinical pathologists should keep in mind that the possibility of postmortem hypostatic hemorrhage needs to be ruled out when the diagnosis of subarachnoid hemorrhage or cerebral hemorrhage is established.