NRE Step 1 Forensic Medicine MCQs

Answer: IV atropine, doubling until chest clear. This is organophosphate poisoning — acetylcholinesterase inhibition causing muscarinic (secretions, bradycardia, bronchospasm, miosis) and nicotinic (fasciculations, weakness) features. After airway support, give IV atropine and double the dose every few minutes until atropinised: clear chest on auscultation, HR > 80, systolic BP > 80, dry axillae. Pralidoxime is an adjunct in some protocols; it does not replace atropine. Remove contaminated clothes and wash the skin.

• IV pralidoxime alone, without atropine: Oximes are adjuncts at best; atropine reverses the life-threatening muscarinic effects.
• IV naloxone: Pinpoint pupils here are cholinergic, not opioid; the bradycardia and secretions point to organophosphate.
• IV physostigmine, then atropine: Physostigmine is a cholinesterase inhibitor — it would add to the cholinergic poisoning, not reverse it.

Answer: Ia immediate; underlying cause last. Medical certificates of cause of death follow the WHO format: Part I lists the chain from the immediate cause (Ia) back to the underlying cause (lowest line) — e.g. Ia congestive cardiac failure, Ib ischaemic heart disease. Part II lists other significant contributing conditions. Modes of death (cardiac arrest, respiratory arrest) alone should not be used. Unnatural, sudden unexplained or suspicious deaths must be reported to the police/medicolegal authorities instead.

• Ia "cardiac arrest" only: That is the mode of death, not the cause.
• Underlying cause in Part II only: Part II is for contributing conditions.
• Ia "heart failure"; rest left blank: The underlying cause must be recorded too.

Answer: McNaghten rules. The McNaghten rules (1843) state that a person is not criminally responsible if, at the time of the act, because of a disease of the mind, they did not know the nature of the act or that it was wrong. Pakistan’s Penal Code includes a similar provision (act of a person of unsound mind). Voluntary intoxication is generally not a defence. Testamentary capacity concerns whether someone can make a valid will.

• Res ipsa loquitur: Res ipsa loquitur ("the thing speaks for itself") is a negligence doctrine, not a criminal insanity defence.
• Diminished responsibility: Not the defence in Pakistan law (PPC s.84 follows McNaghten).
• Vicarious liability: Vicarious liability makes an employer responsible for employees’ acts; it is unrelated to insanity.

Answer: Professional misconduct. Infamous conduct/professional misconduct (dealt with by the national medical council) includes: issuing false certificates or reports; sexual or improper relationships with patients; abuse of alcohol/drugs affecting practice; covering or associating with unqualified practitioners; fee-splitting and commissions; improper advertising and canvassing; breach of confidentiality; performing unlawful abortions; refusing emergency care; conviction for criminal offences involving moral turpitude. Sanctions range from warning to suspension or removal from the register. Certificates must be based on personal examination and truthful.

• Civil negligence: This is professional misconduct (a false certificate), not civil negligence.
• Acceptable favour: A false certificate is dishonest, not an acceptable favour.
• Therapeutic privilege: Therapeutic privilege does not apply.

Answer: Throttling — homicidal. Throttling: compression of the neck by hand(s). Findings: crescentic fingernail abrasions and discoid fingertip bruises on the neck (the assailant’s or victim’s own nails as she tried to remove the hands), bruising of deep neck muscles, fractures of the hyoid (greater horns) or thyroid cartilage superior horns (more likely in older people with ossified cartilage), congestion, cyanosis and petechial haemorrhages above the level of compression. Manner is almost always homicide — self-throttling is not possible because the grip relaxes with loss of consciousness. Other asphyxias: hanging (oblique, high ligature mark, usually suicide), ligature strangulation (horizontal, low, complete mark — usually homicide), smothering (mouth and nose occlusion — infants, elderly, often few signs), gagging, choking, traumatic asphyxia.

• Hanging — suicidal: Hanging leaves an oblique ligature mark, not fingernail marks.
• Ligature strangulation — homicidal: Horizontal ligature mark, not fingernail marks.
• Smothering — accidental: Smothering involves the mouth and nose, not the neck.

Answer: Multiple-dose charcoal. Gut decontamination: single-dose activated charcoal within 1 hour for adsorbable toxins (not for metals — iron, lithium; alcohols; corrosives; hydrocarbons). Multiple-dose activated charcoal (MDAC) enhances elimination by "gut dialysis"/interrupting enterohepatic circulation — for carbamazepine, dapsone, phenobarbital, quinine and theophylline. Urinary alkalinisation for salicylates (and phenobarbital). Haemodialysis for dialysable toxins causing severe toxicity: salicylates, lithium, toxic alcohols (methanol, ethylene glycol), theophylline, metformin-associated lactic acidosis, valproate. Ipecac, routine gastric lavage and forced diuresis are not recommended. Whole-bowel irrigation for iron, lithium, body packers, sustained-release preparations in selected cases.

• Ipecac-induced vomiting: Ipecac is obsolete and risks aspiration; it doesn’t enhance elimination.
• Forced alkaline diuresis: Urinary alkalinisation helps salicylates, not theophylline.
• Urinary alkalinisation: Urinary alkalinisation is used for salicylates.

Answer: Ethylene glycol. Ethylene glycol (antifreeze/coolant, sweet taste): early inebriation with raised osmolar gap; metabolised by alcohol dehydrogenase → glycoaldehyde → glycolic acid (main cause of acidosis) → glyoxylic → oxalic acid → calcium oxalate deposition: high anion gap acidosis, hypocalcaemia (tetany, QT↑), cardiopulmonary toxicity, AKI (oxalate crystals — envelope (dihydrate) or needle (monohydrate) shaped). Methanol → formic acid → optic nerve damage/blindness, basal ganglia necrosis. Isopropanol → acetone (ketosis without acidosis). Treatment: fomepizole (or ethanol) to block ADH, haemodialysis for severe acidosis/AKI/high levels, bicarbonate, cofactors (thiamine and pyridoxine for EG; folinic acid for methanol).

• Methanol: Methanol causes visual loss and does not form oxalate crystals.
• Isopropyl alcohol: Isopropyl alcohol causes ketosis without a high anion gap acidosis.
• Diethylene glycol: Diethylene glycol causes renal failure but not calcium oxalate crystals.

Answer: Burking. Asphyxial deaths: smothering (nose/mouth closure — pillows, hands); gagging; choking (internal airway obstruction; café coronary — food bolus in intoxicated person mimicking MI); traumatic asphyxia (chest compression — crowd crushes; deep purple face, petechiae); burking (smothering + traumatic asphyxia; named after Burke and Hare); garrotting (ligature from behind); mugging (forearm/elbow neck compression).

• Garrotting: Garrotting is a ligature from behind.
• Café coronary: Café coronary is choking on a food bolus.
• Mugging: Mugging is forearm compression of the neck.

Answer: Loops. Dactylography (Galton–Henry system): patterns — loops (~60–70%), whorls (~25–35%), arches (~5%), composites (rare). Fingerprints are unique (even in identical twins) and permanent, appearing in fetal life; destroyed only by deep dermal injury. Poroscopy (Locard): study of sweat pore arrangement in ridges — useful with partial prints. Other identification: DNA profiling, dental records, superimposition, tattoos, scars.

• Whorls: Whorls are the second commonest.
• Arches: Arches are the least common.
• Composites: Composites are uncommon.

Answer: Strychnine. Strychnine (Strychnos nux-vomica seeds; rodenticide): glycine antagonist at spinal cord inhibitory synapses → tetanic convulsions triggered by stimuli, opisthotonos, risus sardonicus, consciousness preserved between spasms (unlike epilepsy), hyperthermia, rhabdomyolysis, asphyxia. Treatment: quiet dark room, benzodiazepines, airway, cooling; neuromuscular blockade and ventilation in severe cases. Differential: tetanus (history of wound, trismus first, slower onset).

• Datura: Datura causes delirium, dry skin and dilated pupils.
• Organophosphate: OPs cause miosis and secretions.
• Aconite: Aconite causes arrhythmia and tingling.

Answer: Marking nut (Semecarpus). Marking nut (bhilawa, Semecarpus anacardium): black acrid juice (used to mark laundry) — applied to skin produces dark, irregular, vesicular lesions resembling bruises, used to fabricate injuries; features distinguishing from true bruises: itching, vesicles, irregular dark margins, juice also on fingers, no swelling/tenderness of deeper tissue, colour doesn’t change like a bruise. Calotropis latex is also used as an irritant/abortifacient and in infanticide.

• Calotropis latex (aak): Calotropis latex is an irritant abortifacient, not used to fake bruises.
• Abrus seeds (ratti): Abrus seeds are used as sui needles.
• Datura seeds: Datura causes anticholinergic poisoning.

Answer: Body moved after fixation. Livor mortis (postmortem hypostasis): gravitational settling of blood in dependent parts, sparing pressure areas (contact pallor); begins within ~30 min–2 h, well developed by 4–6 h, becomes fixed (does not shift or blanch) after ~6–12 h as blood haemolyses and stains tissues. Lividity on non-dependent surfaces in fixed form means the body was moved after fixation — important in suspicious deaths. Colour clues: cherry-red (CO, cold), bright red/brick red (cyanide), chocolate brown (nitrites, methaemoglobin), dark (asphyxia). Distinguish from bruises by incision (blood within vessels vs extravasated).

• Death by drowning: Drowning does not explain lividity opposite to body position.
• Carbon monoxide poisoning: CO gives cherry-red colour, not displaced lividity.
• Death within the last hour: Within an hour, lividity would not be fixed.