Diatom test: a reliable tool to assess death by drowning?

Background: Post mortem analysis of drowning is a classical problem especially in decomposed bodies recovered from water. One of the important issues in the study of drowning has been the search for a sensitive, specific and easily applicable test for the cause of death. The aim of the present study was to identify the presence of diatoms in cases of death due to drowning and to compare with non-drowning cases. The seasonal variations in the presence of diatoms in water samples collected from different water sources were also assessed.Methods: Specimens of bone marrow, nasal sinus aspirate and lung bits were collected from 50 known drowning cases and water samples from the site of recovery of the bodies. The bone marrow, lung bits in 50 non-drowning cases and their house hold drinking water was also analyzed for detecting presence of diatoms.Results: 50 drowning cases were studied. Only 21 cases showed positive diatom test and the rest showed negative results. Out of the cases the number of drowning was more in the rainy season. It was seen that the diatom population increased in the spring season and decreased in the rainy season. Hence the diatom test showed more negative results during the rainy season. The test was more positive during spring and summer season. In the non-drowning cases, 40 cases showed positive diatom but only 10 showed presences of diatoms in bone marrow.Conclusions: Diatom test in drowning is significant even though occasional diatoms may be recovered in bone marrow in non-drowning cases. As in the diatom test, we are comparing the identical diatoms in both bone marrow and the putative drowning medium. Just the presence of diatoms in tissues is not sufficient in giving a positive opinion in drowning cases. This diatom test is very valuable in drowning deaths especially in decomposed states as other findings of drowning may be lost or obscured due to decomposition.