A body is found lying on its back, but lividity is present over the FRONT of the chest and abdomen. What does this suggest? ANSWER: the body was MOVED after death. MECHANISM: once circulation stops, blood settles under GRAVITY and stains the lowest parts of the body. Lividity therefore forms wherever was lowest during the period it developed. Staining on the front of a body found on its back means the body lay FACE DOWN for a period after death and was subsequently turned. WHY THIS IS THE USEFUL PART: lividity's forensic value is POSITION, not timing. That observation costs nothing to record and has changed the direction of investigations. WHAT NOT TO DO: do not use it, or rigor, or cooling, to state an hour of death.

Why should a doctor NOT estimate the time of death from body temperature and rigor mortis? ANSWER: because the variables are too many and too uncontrolled for the precision such an estimate implies. COOLING depends on: ambient temperature · wind and airflow · clothing · body size and fat · the surface the body lay on RIGOR depends on: temperature · exertion before death · muscle mass CONSEQUENCE IN COURT: a doctor who testifies that death occurred "between four and six hours before" will be cross-examined on every one of those variables and will not be able to defend the precision. Once that estimate is shown to be unsupportable, the rest of their evidence is weakened too. WHAT TO DO INSTEAD: DESCRIBE what you observed. Estimating the post-mortem interval is specialist work, done with the scene conditions in hand.

A wound has RAGGED edges, tissue bridges crossing its depth, and surrounding bruising. What type of wound is it, and what caused it? ANSWER: a LACERATION — caused by BLUNT force. THE THREE FEATURES ALL POINT THE SAME WAY: RAGGED EDGES tearing does not divide tissue cleanly TISSUE BRIDGES strands of stronger tissue survive across the depth BRUISING blunt impact damages surrounding tissue CONTRAST — INCISED WOUND, caused by a SHARP edge: CLEAN edges · NO tissue bridges · usually longer than deep (a STAB wound is the variant deeper than it is long) TISSUE BRIDGES ARE THE SINGLE BEST DISCRIMINATOR between the two.

Why is writing "laceration" for a knife wound a serious error? ANSWER: because in forensic terms LACERATION MEANS BLUNT FORCE — the opposite of what the writer intends. A knife produces an INCISED wound. A laceration is tissue TORN by blunt force. CONSEQUENCE: if the case comes to court alleging a stabbing, a medical record describing a "laceration" states — in the technical language the court applies — 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: if unsure of the classification, DESCRIBE rather than classify. "4 cm wound, clean edges, no tissue bridges" That is an OBSERVATION and cannot be contradicted. The classification is an INFERENCE, and inference is the court's job.

A family present six hours after a meal of wild mushrooms. Two vomited soon after eating; one has just become unwell now. Who is more concerning, and why? ANSWER: the one who became unwell LATE. THE TIMING RULE: species causing EARLY symptoms are generally the LESS dangerous ones. The species that damage the LIVER characteristically produce a LATENT PERIOD, so the patient becomes unwell hours later — often after appearing to recover from any initial upset. SO THE PATTERN IS DANGEROUS IN BOTH DIRECTIONS: - a patient who vomited early may be reassured wrongly - a patient presenting late may be assumed to have a mild illness LATE ONSET AFTER MUSHROOM INGESTION IS THE WORRYING PATTERN. PRACTICAL POINT: keep any remaining mushrooms. Identification frequently matters more than any assay, and families discard them if nobody asks.

A child has swallowed kerosene. Should the stomach be emptied? A. Induce vomiting immediately B. Pass a nasogastric tube and lavage C. Neither — both increase the risk of aspiration D. Give activated charcoal and induce vomiting ANSWER: C. WHY: the danger of hydrocarbons is NOT absorption from the gut. It is ASPIRATION INTO THE LUNG, where they cause a severe chemical pneumonitis. Inducing vomiting or passing a tube increases exactly that risk — so the instinctive action makes the situation worse. THE GENERAL PRINCIPLE THIS ILLUSTRATES: in toxicology, 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 UNSURE: treat the patient and consult a poisons information service before attempting to empty the stomach.

What makes a sample usable as evidence in a suspected poisoning, and what must never be allowed to delay? ANSWER: an unbroken CHAIN OF CUSTODY. 1. LABEL at the bedside, from the patient's own identifiers, at the moment it is taken. 2. SEAL it. 3. RECORD every transfer — who took it, who received it, when. ALSO KEEP what came in with the patient: the container, remaining tablets, the plant or mushroom, and vomit. These often identify the poison faster than any assay, and families discard them if nobody asks. WHAT MUST NEVER BE DELAYED: TREATMENT. Resuscitation comes first; evidence is gathered ALONGSIDE care, never instead of it. A perfectly documented sample from a patient who died while it was collected is a failure, not a success.