Post-mortem computed tomography differentiation of putrefactive gas and air embolism: A case of traumatic carotid-jugular arteriovenous fistula.

Introduction: PMCT is superior to autopsy for identification of intravascular or extravascular gas pockets and their distribution. However, differentiation between air embolism and putrefactive gas can prove challenging due to overlapping imaging findings.

Case report: We report a case of a healthy young man who was involved in a fight, sustained a slash wound to the right side of his head by a kitchen knife and died at the scene. Pre-autopsy PMCT demonstrated complex fractures of the right mastoid bone extending to the right petrous apex and jugular bulb, exposing the right sigmoid sinus. There was also asymmetric intravascular air distribution suspicious of air embolism with ancillary findings of traumatic carotid-jugular pseudoaneurysm and arteriovenous fistulous formation. Post-mortem examination revealed a slash wound measuring 12x2 cm at the right side of the head, cutting through the scalp, right temporal bone, right temporal meninges, right sigmoid venous sinus and part of the right occipital lobe. No intracranial haemorrhage was found on both PMCT and autopsy.

Discussion: PMCT findings of air embolism versus putrefactive air on PMCT are discussed in this case. Detailed history on mechanism, circumstances, time of death and careful analysis of intravascular and extravascular air distribution patterns on PMCT are essential in guiding differentiation of true fatal air embolism and "normal" post-mortem putrefactive air. Needless to say, it is recommended that PMCT be performed as early as possible after death to reduce the chances and presence of artifactual decomposition changes.