Forensic Medicine — Post-mortem Changes, Wounds and Poisoning, NMC MBBS licence examination syllabus (Nepal Medical Council).
Writing "laceration" for a knife wound takes a second and can undermine a prosecution years later.
The first forensic chapter covered the doctor's legal duties — records, certification, negligence. This one covers the three observational areas the syllabus names: what happens to a body after death, how wounds are classified, and the poisonings not already covered clinically.
Three changes begin soon after death, and all three are commonly misused.
Cooling. The body loses heat to its surroundings until the two match. The rate depends on ambient temperature, wind, clothing, body size and where the body was lying — a heavy clothed body in a warm room and a thin unclothed one outside behave completely differently.
Rigor mortis. Muscles stiffen, then relax again as decomposition proceeds. It appears sooner in heat and after exertion before death, and later in the cold.
Lividity. Once circulation stops, blood settles under gravity and stains the lowest parts of the body, leaving pale areas where pressure prevented it — under the shoulder blades of a body lying on its back, or where clothing was tight.
Lividity's real forensic value is not timing but position. Staining on a surface that could not have been lowest, given how the body was found, suggests the body was moved after death. That single observation has changed the direction of investigations, and it costs nothing to record.Four wound types account for most of what you will see and record.
This deserves its own section because it is the commonest forensic error made by clinicians, and it is entirely avoidable.
"Laceration" is routinely written in emergency notes to mean any skin wound, including knife wounds. In forensic terms it means the opposite of what the writer intends: a laceration is caused by blunt force. A knife produces an incised wound.Why it matters: when a case comes to court and the allegation is a stabbing, a medical record describing a "laceration" states — in the technical language the court will apply — that the injury was caused by a blunt object. That contradicts the prosecution case, and the doctor is asked to explain a discrepancy they did not know they had created.
The safe habit is the one from the first forensic chapter: if you are not confident of the classification, describe rather than classify. "A 4 cm wound with clean edges and no tissue bridges" is accurate, useful, and cannot be contradicted. The classification is an inference; the description is an observation.
Organophosphate poisoning, paracetamol and snakebite are covered in the poisoning and environmental emergencies chapters. Three others are worth knowing because each has a feature that misleads.
Mushroom poisoning. The critical distinction is timing. Species causing early symptoms — within a short time of eating — are generally the less dangerous ones. The species that damage the liver characteristically produce a latent period, so the patient becomes unwell some hours later, often after apparently recovering from initial symptoms.
That is dangerous in two directions: a patient who vomits early may be reassured wrongly, and a patient presenting late may be assumed to have a mild illness. Late onset after mushroom ingestion is the worrying pattern, not the early one.
Aluminium phosphide. Used as a grain preservative and available in agricultural communities. It releases a toxic gas on contact with moisture, and causes profound circulatory collapse. There is no antidote, and mortality is high — so the management is supportive and intensive, and prevention through storage and access control matters more than any treatment.
Kerosene and other hydrocarbons. The instinctive response — make the patient vomit, wash out the stomach — is actively harmful. The danger is not absorption from the gut but aspiration into the lung, where hydrocarbons cause a severe chemical pneumonitis. Inducing vomiting or passing a tube increases exactly that risk.
This is a recurring shape in toxicology and worth generalising: the intuitive first action is sometimes the harmful one. Decontamination decisions depend on the substance, not on a general rule that removing poison is always good. Where you are unsure, treat the patient and consult a poisons resource before attempting to empty the stomach.In a suspected poisoning that may become a legal case, a sample is only as good as the account of who handled it.
But none of this delays treatment. Resuscitation comes first, and evidence is gathered alongside care rather than instead of it. A perfectly documented sample from a patient who died while it was being collected is a failure, not a success.
Suspect poisoning when the story does not fit. A young person with unexplained collapse, several people unwell together after a shared meal, or a clinical picture that matches no ordinary diagnosis. Toxicology is diagnosed by considering it.
Not every poisoning is intentional. Accidental ingestion in children, occupational exposure, contaminated food and drug interactions all present as poisoning. Assuming intent shapes the questions asked, and can produce a hostile consultation with a patient who took the wrong tablet. Ask what happened before deciding why.
No post-mortem timings, temperature formulae, antidote doses or sample volumes appear here: the post-mortem interval depends on too many uncontrolled variables to state in hours, and clinical management belongs to the poisoning chapter. Use your local protocol and a poisons information service.
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