Medico-legal interpretations of gas on postmortem CT: a scoping review

The use of postmortem computed tomography (PMCT) in forensic investigations has increased during recent years. PMCT differs from clinical CT due to the inevitable manifestation of postmortem changes that varies significantly between cases. However, differentiating between gas with an antemortem origin (e.g. gas embolism) vs. gas with a postmortem (putrefactive gas) origin presents a critical challenge in forensic medicine. This scoping review evaluated how gas distribution patterns on PMCT may aid in determining gas origin. In accordance with PRISMA-ScR guidelines, searches were conducted in PubMed, Web of Science, and CINAHL. 10,133 records were identified, of which 28 studies met the inclusion criteria. Overall, evidence was limited and heterogeneous, with substantial variation in terminology, gas assessment methods and study populations. Evidence suggests that differentiating pathological gas from putrefactive, resuscitation-related artefacts, and postmortem effects such as off-gassing remains a significant diagnostic challenge postmortem. Nevertheless, certain early PMCT patterns may assist interpretation. Within the first 24 h postmortem, intravascular and cardiac gas more commonly reflect systemic or traumatic mechanisms, although putrefaction cannot be excluded. Isolated cardiac gas may result from resuscitation efforts, whereas combined cardiac and intrahepatic gas more strongly suggests decomposition. In diving fatalities, embolic gas findings may be compounded by postmortem off-gassing as well as decomposition changes, and should be interpreted alongside dive profiles and, where available, gas sampling. Small gas collections adjacent to laryngeal structures may indicate trauma when other sources and decomposition are excluded. Overall, integrating PMCT gas distribution with contextual information and ancillary analyses may help understand gas origin, but further targeted research is required.