Diatoms pass through the gastrointestinal barrier and lead to false-positive: an animal experiment

The diatom test has been used by forensic pathologist as standard for drowning, but the occurrence of false-positive results (presence of diatoms found in the tissues of subjects who died from causes other than drowning) draws criticism regarding the specificity of the test. Diatoms within food or water can be ingested through the gastrointestinal tract. However, the mechanisms of how the diatoms reach distant organs such as the lung, liver, and kidney have not been studied. In this article, we simulated the process of diatoms entering the gastrointestinal tract using gastric lavage on experimental rabbits. Diatoms are detected in lymph from a lymphatic vessel at the root of the mesentery, portal vein blood, aortic blood, lung, liver, and kidney samples in the gavage group. Of diatoms, 76.24% were the centric diatom, 99.86% of diatoms have a maximum size of less than 50 µm, and most of diatoms concentrate in the lung. Our study provided the evidence supporting the theory that the diatoms could pass through the gastrointestinal barrier and reach the rabbits’ other internal organs. The diatoms could reach internal organs through the portal vein and lymphatic vessel at the root of the mesentery. This provides us new insight into our understanding of false-positive diatom test in forensic pathology.