[Place of pathology in the forensic diagnosis of drowning]

The diagnosis of drowning is one of the most difficult in forensic pathology. Drowning is death through the aspiration of fluid into the air passages. Signs of immersion only demonstrate submersion of the body for a period of time but are not signs of drowning. The best signs of drowning are froth around the mouth and nostrils and lung distension. Lung histology in drowning victims shows non-specific lesions such as "emphysema aquosum" and alveolar edema. The diatom test for drowning requires a careful protocol to avoid possible contamination. Sample collection (cardiac blood, lung, liver, kidney tissue, bone marrow and brain) should be performed during the first part of the autopsy. Sample preparation requires chemical or enzymatic digestion. The diatom test should be both qualitative and quantitative. Species recovered from the body must correspond to those from the site of drowning and approximately in the same proportions. The diatom test has poor sensitivity and thus is much debated because it is always difficult to rule out possible contamination. Moreover, a negative diatom test cannot rule out drowning as the cause of death. The diagnosis of drowning is based on police investigations, forensic autopsy, microscopic analysis, and biochemical tests, but never solely on pathology findings.