Fictional medical examiners have no trouble telling if somebody drowned. In real life, that determination can be hard.
The classic finding in drowning is a cone of white froth bubbling out of the nose and mouth. Froth forms when inhaled water mixes with surfactant, a soapy substance manufactured in the lungs that stabilizes the tiny, bubble-like air sacks.
Inhaled water isn’t the only cause for the formation of froth. Both congestive heart failure and a depressant drug overdose can cause fluid from the blood to leak into the lungs. This fluid mixes with surfactant in the same way as inhaled water and produces the same result.
No test, and no observation I can make during the autopsy of a body pulled from water, can reliably indicate whether froth issuing from the lungs formed from inhaled water or from fluid leakage caused by heart failure or drugs.
So based only on the presence of a froth cone, it’s impossible to differentiate between somebody who drowned, somebody who died of congestive heart failure and collapsed into the water and somebody who died of an overdose and was thrown into the water by people for whom the death would be troublesome or incriminating.
On TV, drug test results are available in minutes. In real life, tests take weeks to complete. When the results are finally in, the absence of drugs in a body recovered from the water supports the conclusion that a froth cone indicates drowning.
But a high level of a depressant drug doesn’t prove death by overdose. Some people with remarkably high drug levels survive them, and an intoxicated person who enters the water voluntarily or while disoriented is more likely to drown.
The hearts of people who die of congestive failure look the same as they did the day before when they functioned adequately. So when a person pulled from the water has a bad heart, I can’t safely assume that heart failure was the cause of death. One of the worst-looking hearts I ever saw belonged to a pedestrian who died when he was hit by a truck.
Most but not all people who drown swallow water. A large amount of water in the stomach supports drowning as the cause of death, but the absence of water doesn’t rule out drowning. And if a body has been in rough water for hours, wave action can propel water into the mouth and stomach passively.
Some years ago, forensic pathologists hoped that water-dwelling micro-organisms called diatoms could prove drowning in some cases. Diatoms are highly diverse in appearance. Perhaps a microscopic match between diatoms in the lungs and diatoms in the water from which the body was recovered would prove that water from that particular source had been inhaled.
The idea didn’t pan out. Diatoms are everywhere including in the air we breathe. We all have lots of diatoms in our bodies. The harder you look for them, the more you find.
Since no test or autopsy finding proves drowning, the medical examiner must carefully weigh the circumstances surrounding a death before making a determination.
But not all drownings are witnessed, some witnesses have reason to lie and it’s often the case that available “circumstances” amount to little more than a report that the body was found floating in the water.
The certification that a person drowned is often an educated guess based on a combination of suggestive autopsy findings, compatible circumstances, medical history and professional judgment.
Dr. Carol J. Huser, a forensic pathologist, served as La Plata County coroner from 2003-12. She now lives in Florida and Maryland. Reach her at firstname.lastname@example.org.