Postmortem CT interpretation of hemopericardium and associated signs

Hemopericardium (HP) may result from natural cardiovascular disease or traumatic mechanisms, and distinguishing these etiologies is important in forensic practice. Postmortem computed tomography (PMCT) can characterize the morphology of pericardial blood, but the discriminatory value of specific PMCT features for natural versus traumatic HP remains incompletely defined. This retrospective observational study evaluated 53 autopsy-confirmed cases of HP identified from 4903 medicolegal autopsies performed between January 2022 and December 2024. PMCT was assessed for hyperdense armored heart (HAH), fluid-fluid level (FFL), and flattened heart sign (FHS), with inter-observer agreement evaluated using Cohen's κ. Exploratory quantitative attenuation analysis and multivariable logistic regression were also performed. HAH and FHS were significantly associated with natural HP (p < 0.001 for both), whereas FFL was not significantly associated with HP type (p = 0.090). Inter-observer agreement was perfect for all three features (κ = 1.00; 95% CI, 1.00-1.00). Mean attenuation did not differ significantly between natural and traumatic HP (67.13 ± 10.62 vs 71.43 ± 8.26 HU, p = 0.148). FHS remained significantly associated with HP type in exploratory multivariable analysis (adjusted OR, 0.11; 95% CI, 0.02-0.69; p = 0.018). PMCT identified HP in 49 of 53 autopsy-confirmed cases. These findings suggest that selected PMCT morphological features may provide complementary information for differentiating natural from traumatic HP, but should not be interpreted as evidence of antemortem hemorrhage or fatal tamponade in isolation.