Can pulmonary foam arise after postmortem submersion in water? An animal experimental pilot study

It is difficult to differentiate drowning from postmortem submersion. Pulmonary foam can be found in bodies retrieved from water. It is unknown whether foam is a result of drowning or if it also forms after postmortem submersion. We divided deceased piglets into three groups: postmortem saltwater submersion (N = 20), postmortem freshwater submersion (N = 20) and dry-land controls (N = 20). All carcasses underwent endoscopic examination within 24 h of death and the presence of external and internal pulmonary foam was scored. No external foam was detected in the postmortem freshwater or the postmortem saltwater group. Internal foam was seen in 35% of the postmortem freshwater and 40% of the postmortem saltwater group. No external or internal foam was detected in the dry land control group. The literature shows external as well as internal foam in drowned humans. Internal foam is seen in postmortem submersion in the current piglet study and antemortem submersion in the literature in humans, and can therefore not be used to support/refute the diagnosis of drowning. No external foam was present in the postmortem submersed piglets, yet has been described in drowned humans. Hence the presence of external foam in bodies recovered from water may be indicative for drowning. The presence of external foam is a potentially valuable clinical sign in distinguishing drowning from postmortem submersion.