Macroscopical, Microscopical, and Laboratory Findings in Drowning Victims

Abstract

The medicolegal investigation of bodies found in water focuses on victim identification, evaluation of postmortem submersion time, and determination of the cause and manner of death. In any given case the circumstances surrounding death, environmental factors, victim’s preexisting diseases, and autopsy findings must be appropriately considered in reaching a diagnosis of the cause and manner of death. In addition to drowning, injuries, intoxications, or natural conditions are all among the potential causes of death in bodies found in water or the factor that may have contributed to the fatal outcome. The interpretation of autopsy findings in putative drowning requires a basic knowledge of the pathophysiology of drowning. Hypoxemia plays a primary role in death by drowning, whereas serum electrolyte changes may be observed in experimental models but have little or no clinical significance in humans. The volume of liquid inhaled depends on factors such as the duration of laryngospasm, the number and depth of respiratory movements before death, and the time of onset of cardiac arrest. Recent studies suggest that the actual incidence of drowning without liquid inhalation is much lower than previously estimated. The most important morphological changes associated with drowning are those related to liquid penetration into the airways: external foam, frothy liquid in airways, and lung overexpansion. However, these changes are not specific to drowning. The diagnostic value given to microscopic pulmonary changes varies significantly and is limited mostly by their heterogeneous distribution within the lung parenchyma. Laboratory methods for the diagnosis of drowning have their rationale in the shift of liquid and electrolytes across the pulmonary air-blood barrier, which may cause blood volume and electrolyte changes. Although some methods have been reappraised recently, their usefulness is greatly hampered by factors such as the variable volume of drowning liquid penetrating the airways, the differing duration of the drowning process, and postmortem biochemical instability. Contributions on the reliability of the diatom method for the diagnosis of drowning have yielded widely divergent opinions, of which the most critical often rely on studies lacking a rigorous methodology. Until standardized protocols and reliable separation values for diatoms between control and drowning cases are established, the diatom method cannot be accepted in definitively proving a diagnosis of drowning in the courtroom, but rather represents a useful supportive tool for the diagnosis of death by drowning.