Concordance analysis of diatom types and patterns in lung tissue and drowning medium in laboratory animal model

Diatom test has been widely used in the diagnosis of drowning and inferring the drowning site. One of the issues is whether the concordance of the diatom types and patterns between the drowning victim’s organs and media should be considered an essential requirement for the diagnosis of drowning. In this study, lung tissues from 20 rabbits and drowning media were studied by the Microwave Digestion–Vacuum Filtration–Automated Scanning Electron Microscopy method, and four methods, type consistency, coefficient of similarity, squared-chord distance, and cluster analysis, were introduced to analyze the diatom types and patterns for evaluating the value of diatom consistency in drowning cases. The results showed that diatom types and patterns in lung tissues do not perfectly match the drowning medium, and they are sometimes concordant with the drowning medium sampled from other than drowning site. We should be cautious when using diatom detection to infer drowning sites.