Fat embolism in forensic pathology

Abstract

The subject of fat embolism must be taken in conjunction with bone marrow embolism and can be considered on anatomical and on clinical grounds. From the forensic aspect, the incidental finding is of major importance as the discovery of pulmonary fat or bone marrow embolism at autopsy should be proof of bone injury having been sustained in life. This hypothesis has been tested by studying 400 aviation fatalities with fracture. The overall incidence of pulmonary fat embolism was 63% (37% of significant degree) and of bone marrow embolism 33%. The occurrence of both was directly associated with an intact cardiovascular system and with the time taken to die but was inversely related to the degree of bone injury. Fat embolism was found to be a more sensitive index of ante-mortem trauma but bone marrow embolism is a more specific marker of fracture. When correlated with carboxyhaemoglobin levels in those persons exposed to fire, a small number of anomalous cases of embolism of both positive and negative nature were observed. Provided this possibility, and the effect of attempted resuscitation, is taken into account, the use of pulmonary fat embolism as an indicator of ante-mortem trauma is a most valuable tool in forensic pathology. Pulmonary fat embolism is unlikely to be fatal. When the hydrostatic effect of arteriolar blockage results in capillary involvement, the occasionally fatal condition of systemic embolism develops. This is of forensic importance in so far as it must raise the possibility of novus actus interveniens.