Forensic analysis of diatom in the spleen and heart in Sprague-Dawley rats

Post-mortem diagnosis of drowning is a real challenge, especially in a decomposed body. The diatom test is considered a reliable scientific assessment in several countries including China. The lungs, liver, and kidneys are usually used in the diatom test, whereas the spleen and heart are rarely reported. In our study, we set up five water samples with different concentrations of diatoms. One-hundred and twenty adult SD rats were employed, assigned to the Drowning Group (DG), Post-mortem Submersion Group (PSG), Drowning Control Group (DG-Control), and Post-mortem Submersion Control Group (PSG-Control). Rats in DG and PSG were submerged in water samples, respectively. After the microwave digestion and vacuum filtration method for diatom enrichment, the diatom numbers were counted. The results showed no diatom was found in either the DG-Control or PSG-Control group. Although significant differences in the diatoms number were found between the DG and PSG groups, the heart and spleen revealed no significant differences. These two organs equally had high specificity and low sensitivity. Based on our data, we concluded that the heart and spleen can be used for the diagnosis of drowning, and detection of diatoms in systemic circulation organs may be more suitable for the diatom test, especially when exogenous contamination is avoided.