Pleural fluid accumulation detectable on paediatric post-mortem imaging: a possible marker of interval since death?

The aim of this preliminary study is to evaluate whether pleural fluid accumulates following death in a predictable manner, in particular whether such collections are related to post-mortem interval.

Images acquired by post-mortem magnetic resonance imaging (PMMR) were both subjectively and objectively assessed for extent of pleural fluid accumulation. Total thoracic volume and pleural fluid volume were calculated using segmentation functions on OSIRIX software. The percentage of pleural fluid as a percentage of thoracic volume was calculated, to account for variation in subject size. The cause of death as per the final autopsy report and the interval from death to imaging were also recorded.

Twelve perinatal deaths/stillbirths (mean gestation 38 weeks, range 24-48 weeks, male/female 5:7) and 11 childhood deaths (mean age 1 year, range 1 day-4 years, male/female 3:8) were assessed. The mean interval from death to imaging for all cases was 7.5 days (range 1-23 days). Pleural fluid was present in almost all cases, and the mean percentage pleural effusion as a proportion of thoracic volume was 3.3 % (range 0.2-9.5 %). There was a significant correlation between the post-mortem interval and the amount of pleural fluid in childhood deaths (p < 0.05) but no significant relationship for perinatal deaths.

The accumulation of pleural fluid detectable on PMMR in children is related to post-mortem interval. If this holds for a larger population, it may therefore be a useful marker for estimating time of death. A similar relationship was not found for perinatal deaths and stillbirths, the reasons for which remain uncertain.