Evaluation of L/D ratio in a water-related case for the differentiation between drowning and postmortem immersion.

It is a difficult task to determine the cause of death for decomposed bodies found in water. Diatom test has been shown to provide supportive evidence for the diagnosis of drowning. According to our previous studies, the ratio of diatom content in lung tissue to diatom content in drowning medium (L/D ratio) is a very useful indicator to distinguish between drowning and postmortem immersion. In this article, we presented a case of a highly decomposed body being recovered from water with no significant findings on its cause of death. We applied the microwave digestion-vacuum filtration-automated scanning electron microscopy method (MD-VF-Auto SEM) to detect diatoms in the organs and suspected drowning medium. In this case, positive results are found in diatom tests of lung tissue, liver tissue and kidney tissue, while the L/D ratio analysis suggested that the victim was more likely to suffer from postmortem immersion. Taking the result of L/R ratio and other findings into consideration, we can eliminate the possibility of drowning. With continuous study, the L/D ratio analysis would be a valuable tool in diagnosis of drowning.