Relation between intravascular and intraorgan gas volume and quantity via postmortem CT and putrefaction.

This study assessed the relationship between intravascular and intraorgan gas volume and quantity via postmortem computed tomography (PMCT) and putrefaction. Consecutive medico-legal autopsy and PMCT data from January 2018 through December 2020 (n = 1,156) at our institution were collected. Cases of injury within deep subcutaneous lesions (n = 146), air embolism (n = 2), resuscitation (n = 369), or severe postmortem changes (n = 192) were initially excluded. However, of these 192 cases with severe postmortem changes, fifty-one cases were reincluded for intraorgan gas assessment because their target organs were maintained in the PMCT images for the gas assessment. A total of 498 cases were included for intraorgan gas assessment, whereas 447 cases were included for intravascular gas assessment. The putrefaction level is classified as follows: stage 1 (S1), no visual putrefaction; S2, partial putrefaction; and S3, total putrefaction. Intravascular gas was classified as follows: Grade 0 (G0); no gas, G1; maximum gas diameter within 10 mm, G2; larger than 10 mm; and G3, larger than half of the maximum anteroposterior diameter of the atrium or ventricle. Intraorgan gas was classified as follows: G0, no gas; G1, nodular gas; G2, dendritic gas; and G3, foamy gas. Intravascular and intraorgan gas in each organ increased significantly as putrefaction progressed (p < 0.01). G1 gas in the right heart appeared from S1 in approximately 20% of the cases, and there was no intravascular G2 or G3 gas in S1. Gas in the liver appeared from S1 in approximately 22% of the cases. The amount of G3 gas in each organ increased significantly in S3. PMCT revealed that intravascular and intraorgan gas accumulated as putrefaction progressed. The G2 and G3 gases in S1 were unusual.