Here are comprehensive answers to all the common forensic medicine viva questions, sourced from standard Indian textbooks (Reddy's Essentials of Forensic Medicine 36th ed. 2026, Parikh's Textbook, PC Dikshit).
FORENSIC MEDICINE & TOXICOLOGY - COMPLETE VIVA ANSWERS
SECTION 1: THANATOLOGY
Q1. Define Death. Types of Death?
Death = permanent and irreversible cessation of all vital functions of the body, including the brain, heart, and lungs.
Types:
| Type | Description |
|---|
| Somatic (Clinical) Death | Cessation of respiration, circulation, and brain function |
| Molecular (Cellular) Death | Individual cells die progressively after somatic death (brain cells first, within 3-5 min) |
| Brain Death | Permanent cessation of all brain functions including brainstem |
| Local Death | Death of a part, e.g., gangrene |
| Suspended Animation | Apparent death - vital functions so depressed that they appear absent (near-drowning, electrocution, drug overdose) |
Q2. Signs of Death - Certain vs Uncertain
UNCERTAIN (Presumptive) signs - may occur in conditions simulating death:
- Cessation of respiration
- Cessation of heartbeat
- Loss of sensation and voluntary movement
- Pallor and loss of skin elasticity
- Changes in eyes (loss of corneal reflex, glazing)
- Loss of muscle tone (primary flaccidity)
CERTAIN (Absolute/Positive) signs - cannot occur in living person:
- Postmortem lividity (Livor mortis)
- Rigor mortis
- Decomposition/Putrefaction
- Incineration/Decapitation (obvious destruction)
Sequential postmortem changes:
- Immediate - insensibility, cessation of respiration and circulation
- Early - pallor, eye changes, primary flaccidity, body cooling, livor mortis, rigor mortis
- Late - putrefaction, adipocere, mummification
Q3. Rigor Mortis
Definition: Stiffening and shortening of muscles following primary flaccidity after death.
Mechanism:
- In life: ATP keeps actin and myosin filaments separate
- After death: glycogen depletes → ATP cannot be resynthesized → actin and myosin fuse into a stiff dehydrated gel → rigor mortis
- pH changes from alkaline to acidic (lactic acid accumulation)
- Persists until autolysis of myosin and actin occurs during putrefaction → secondary relaxation
Onset and Duration (Temperate climate, India):
- Onset: 1-2 hours after death (heart stiffens within 1 hour)
- Complete: 6-12 hours
- Persists: 24-48 hours
- Disappears: 48-60 hours (secondary relaxation)
Order of appearance: Involuntary muscles (heart) first → then voluntary muscles (jaw, neck) → descends to trunk → lower limbs (Nysten's law)
Factors affecting rigor mortis:
- Hastens onset: High temperature, physical activity before death, convulsions, strychnine poisoning, emaciation, children
- Delays onset: Low temperature, cold environment, fat individuals
- Duration shortened by: High temperature, putrefaction, decomposition
Medico-legal importance:
- Helps estimate time since death
- Cadaveric spasm (instantaneous rigor) indicates ante-mortem grip
- Can fix posture of the body at time of death
Q4. Postmortem Lividity (Livor Mortis)
Definition: Purplish-red discoloration of skin in dependent parts of body due to gravitational settling of blood in capillaries and venules after death.
Timing:
- Begins: 30 minutes to 2 hours after death
- Fixed (non-blanching): 6-12 hours (when blood haemolyzes and stains tissues)
- Fully formed: 8-12 hours
Medico-legal importance:
- Sign of death
- Estimate time since death
- Position of body at time of death
- If lividity is on non-dependent surface → body was moved after 6-8 hours
- If two sets of lividity → body was moved
Special colours:
- Cherry red: CO poisoning, cyanide poisoning, cold temperatures
- Brownish: Nitrate/nitrite poisoning (methaemoglobin)
- Absent: Severe anaemia, profuse haemorrhage
- Greenish: Hydrogen sulphide poisoning
Q5. Putrefaction / Decomposition
Definition: Breakdown of complex compounds of the body by bacteria (mainly Clostridium welchii) into simpler substances.
Signs (in order):
- Greenish discoloration of skin - begins in right iliac fossa (caecum → most bacteria) within 2-3 days in India
- Marbling - greenish-black discoloration along blood vessels
- Bloating of face, body
- Skin blisters with foul-smelling fluid
- Liquefaction of soft tissues
- Skeletonisation (months to years)
Factors accelerating putrefaction: Heat, moisture, trauma, wounds, air-access
Factors retarding: Cold, dry conditions, lime, embalming, antiseptics
Special late changes:
- Adipocere: Conversion of body fat into a waxy substance (hydroxy fatty acids). Seen in warm, moist, airtight conditions (graves, water). Takes 3-12 months. Helps preserve identity.
- Mummification: Dessication/drying of body. Seen in hot, dry, airy conditions (deserts). Preserves shape. Skin becomes leathery brown.
- Saponification: Another term for adipocere formation.
Q6. Estimation of Time Since Death
Methods:
- Cooling of body (Algor Mortis): Body loses ~1°C per hour until it reaches ambient temperature. Formula: TSD = (37 - rectal temp °C) ÷ 1.5 (approx.)
- Rigor mortis - see above
- Livor mortis - see above
- Putrefaction - for longer intervals
- Stomach contents - empty = 4-6 hours after last meal; partially digested = 2-4 hours
- Vitreous potassium: rises predictably after death; K+ >15 mmol/L suggests >72 hours
- Entomology: type of insect larvae (forensic entomology)
- Diatoms (for drowning)
Q7. Cadaveric Spasm (Instantaneous Rigor)
- Instantaneous stiffening of a group of muscles at the moment of death, without primary flaccidity
- Seen in: drowning (hands clutch weeds/rope), shooting (hand grips weapon)
- Medico-legal significance: Proves ante-mortem grip; cannot be produced artificially after death
SECTION 2: IDENTITY
Q8. Methods of Identification of Unknown Body
DETAILS (Mnemonic: DAMP FIGS):
| Method | Description |
|---|
| General | Age, sex, stature, build, complexion |
| Anthropometry (Bertillon) | Body measurements - historical |
| Fingerprints (Dactylography) | Most reliable for living and dead |
| Teeth (Odontology) | Gustafson's method |
| Bones | Ossification, skeletal features |
| DNA fingerprinting | Most accurate, uses blood/hair/semen |
| Scars, deformities, tattoos | Personal identity |
| Superimposition | Skull matched to photograph |
| Facial reconstruction | Clay modeling over skull |
| Blood group | ABO, Rh |
| Occupational marks | Callosities, staining |
Q9. Gustafson's Method (Age from Teeth)
Six features evaluated microscopically, each scored 0-3:
- Atrophy of root (0-3)
- Secondary dentine deposition (0-3)
- Cement apposition at root (0-3)
- Periodontosis (root bone loss) (0-3)
- Resorption of root apex (0-3)
- Transparency of root dentine (0-3)
Total score (0-18) → correlated to a regression equation → approximate age.
Memory: ASCPRT - "A Scoring Chart Predicts Real Time"
Q10. Ossification Centers - Medico-legal Importance
Important centers for age estimation:
| Age | Ossification Event |
|---|
| Birth | Lower femoral, upper tibial epiphysis fuses |
| 16-17 yr | Medial clavicle starts |
| 18-21 yr | Wisdom tooth erupts |
| 25 yr | Medial end of clavicle fuses completely (last to fuse) |
| 30 yr | Union of vertebral epiphyses |
Medico-legal use:
- Determines if accused is major (>18) or minor
- Useful in age determination for marriage, juvenile justice
- X-ray of left hand-wrist - most useful for children (bone age vs chronological age)
SECTION 3: WOUNDS & INJURIES
Q11. Classification of Mechanical Injuries
A. Blunt Force:
- Abrasion (graze, imprint, pressure)
- Contusion (bruise)
- Laceration
B. Sharp Force:
- Incised wound (cut)
- Stab/puncture wound
- Chop wound
C. Mixed:
D. Firearm injuries
Q12. Difference: Incised vs Lacerated vs Contused
| Feature | Incised Wound | Lacerated Wound | Contusion |
|---|
| Cause | Sharp cutting object | Blunt force | Blunt force |
| Edges | Clean, sharply cut | Irregular, ragged | Intact skin |
| Margins | Well-defined | Bruised, irregular | Discoloured |
| Depth | Greater than length | Shallow usually | No breach of skin |
| Bridge tissue | Absent | Present (blood vessels, nerves bridge the gap) | Absent |
| Bleeding | Profuse | Less | No external bleeding |
| Infection | Less | More | Less |
| Example | Knife cut | Hit with rod | Black eye |
Q13. Defense Wound
- Injuries on forearms, hands, upper arms, inner thighs
- Result of victim trying to protect themselves
- Medico-legal significance: Indicates victim was alive and conscious; usually homicidal; not suicidal
Q14. Hesitation Cuts / Tentative Cuts
- Multiple superficial, parallel, shallow incised wounds
- Usually on wrists, neck, forearms
- Indicate suicide - person tests pain before inflicting fatal wound
- Useful in differentiating suicide from homicide
Q15. Vital Reaction
Definition: The tissue response that occurs in a living person at the time of injury.
Signs of vital reaction:
- Haemorrhage at wound site
- Inflammatory reaction (redness, swelling)
- Wound contraction (due to elastic fibers)
- Embolism - fat, air, etc.
- Healing changes - granulation tissue
- Diatom distribution in tissues (in drowning)
Medico-legal use: Determines if injury is ante-mortem or postmortem.
Q16. Ante-mortem vs Postmortem Injuries
| Feature | Ante-mortem | Postmortem |
|---|
| Hemorrhage | Present (arterial spurting) | Absent (oozing only) |
| Vital reaction | Present | Absent |
| Inflammation | Present | Absent |
| Wound edges | Gaping, retract | Not gaping |
| Clot | Firm, organized | Soft, unorganized |
| Histology | Leukocyte infiltration | Absent |
Q17. Firearm Injuries - Entry vs Exit
Entry wound:
- Round/oval, punched-out
- Inverted margins
- Smaller than exit
- Burning, blackening, tattooing, singeing around (if close range)
- Collar of abrasion (grease collar)
Exit wound:
- Irregular, stellate/cruciate
- Everted margins
- Larger than entry (bullet expands)
- No burning, tattooing
- No collar of abrasion
Range findings:
| Range | Findings |
|---|
| Contact | Star-shaped laceration, singeing, burning, blackening, cruciate |
| Close (<15 cm) | Burning, blackening, tattooing, singeing |
| Intermediate (15-60 cm) | Tattooing (unburnt powder), no burning |
| Distant (>60 cm) | Only collar of abrasion, no other marks |
Tattooing = unburnt powder particles embedded in skin (cannot be wiped off)
Blackening/Fouling = soot/carbon deposition (can be wiped off)
Singeing = burning of hair/skin hairs
Q18. Rifling
- Spiral grooves inside gun barrel
- Impart spin to bullet for accuracy and stability
- Lands = raised ridges; Grooves = the cuts between lands
- Bullet acquires land and groove marks → used for ballistic identification
SECTION 4: ASPHYXIA
Q19. Define and Classify Asphyxia
Definition: A condition caused by interference with respiration or lack of oxygen in respired air, leading to deprivation of oxygen to organs and tissues (along with failure to eliminate CO2), causing unconsciousness or death.
Classification:
- Mechanical: Smothering, hanging, strangulation, throttling, choking, drowning, traumatic asphyxia, cafe coronary
- Pathological: Laryngeal spasm, pulmonary oedema, pneumonia, emphysema
- Toxic: CO poisoning, narcotic drugs, alcohol, HCN
- Environmental: Oxygen-deficient atmosphere
- Positional: Postural asphyxia, crucifixion
Q20. General Postmortem Signs of Asphyxia
- Cyanosis - bluish discoloration of lips, fingernails, mucous membranes
- Congestion - face, brain, viscera
- Petechial haemorrhages (Tardieu spots) - subpleural, subconjunctival, subpericardial
- Fluidity of blood - dark and fluid (due to CO2)
- Engorgement of right side of heart
- Oedema of lungs
- Froth (fine, white/pinkish) in air passages
Q21. Tardieu Spots
- Petechial haemorrhages (pin-point subpleural and subpericardial bleeds)
- Due to: rupture of small capillaries from increased venous pressure during asphyxia
- Seen on: visceral surface of pleura, epicardium, conjunctiva, brain
- Named after: Auguste Ambroise Tardieu (French physician)
- Classic sign of asphyxial death, especially strangulation
Q22. Hanging vs Strangulation - Differences
| Feature | Hanging | Strangulation |
|---|
| Constriction | By weight of body | By hand or ligature |
| Ligature mark | Oblique, incomplete, parchmentised | Horizontal, complete |
| Petechiae | Less common (carotid pressure > venous) | Very common |
| Fracture of neck bones | Common in judicial hanging | Rare |
| Hyoid fracture | Less common | More common |
| Mode | Usually suicidal | Usually homicidal |
Judicial (complete) hanging:
- Fracture-dislocation of C2-C3 (Hangman's fracture)
- Cervical cord transection
- Instantaneous death
Homicidal hanging:
- Manual strangulation - fingermarks on neck
- Ligature strangulation - horizontal, complete ligature mark
Q23. Drowning
Definition: Death due to asphyxia caused by immersion of external respiratory openings (nose and mouth) in liquid.
Types:
- Wet drowning: Water enters lungs (most common, 85%)
- Dry drowning: Laryngeal spasm prevents water entering; lungs dry (~15%)
- Secondary drowning: Recovery followed by delayed death hours later
Postmortem findings:
- Wet skin, wrinkling/maceration ("washerwoman's hands")
- Froth in airways
- Lungs - overinflated, waterlogged (wet, heavy, crepitant - "emphysema aquosum")
- Diatoms (algae) in lungs, brain, bone marrow, liver
- Gettler's test (outdated): chloride content of blood higher in left heart if freshwater drowning; higher in right heart if saltwater
Diatom Test: Most reliable confirmatory test for drowning. Diatoms (silicon-walled algae) enter bloodstream via damaged alveolar capillaries. Found in lungs, liver, bone marrow. Presence in bone marrow confirms ante-mortem drowning.
Q24. Cafe Coronary
- Sudden death from food bolus (usually meat) obstructing the larynx/trachea
- Classic setting: restaurant dining, alcohol-intoxicated
- Mimics cardiac death ("cafe coronary")
- Heimlich maneuver is emergency treatment
- Postmortem: food bolus found in larynx
Q25. Smothering, Choking, Throttling, Gagging, Mugging
| Type | Mechanism |
|---|
| Smothering | Closure of nose + mouth by hand, pillow |
| Choking | Foreign body in larynx/trachea |
| Throttling | Manual strangulation - hands around neck |
| Gagging | Cloth stuffed in mouth |
| Mugging | Arm or leg across neck (arm lock) |
| Burking | Body pressure + smothering simultaneously |
SECTION 5: SEXUAL OFFENCES
Q26. Definition of Rape (as per BNS/IPC)
Section 63, BNS (S. 375, IPC): A man is said to commit rape if he:
(a) Penetrates his penis into vagina, mouth, urethra, or anus of a woman
(b) Inserts any object/body part into vagina, urethra, or anus
(c) Manipulates body to cause penetration
(d) Applies his mouth to vagina, anus, or urethra
Seven circumstances (consent absent/invalid):
- Against her will
- Without her consent
- Consent obtained by fear of death or hurt
- Impersonation (she believes he is her husband)
- Consent invalid due to unsoundness of mind/intoxication
- Under 18 years of age (with or without consent)
- Unable to communicate consent
Punishment: Minimum 10 years; may extend to life imprisonment (Section 64, BNS/S. 376 IPC)
Q27. Medico-legal Examination in Rape
Examine promptly (within 24 hours ideally). Requires informed consent.
Findings to look for:
- General: injuries on face, breasts, thighs, wrists (restraint)
- Perineum: bruises, abrasions, lacerations
- Hymen: fresh tears (radial tears), bleeding
- Vagina: lacerations, discharges, semen
- Posterior fourchette: tears (classic)
- Cervix: bruising
Samples to collect:
- High vaginal swab for semen (acid phosphatase test, spermatozoa)
- Fingernail clippings
- Blood for DNA
- Pubic hair combings
- Clothing
Two-finger test (Per vaginum examination): Declared unconstitutional and unscientific by Supreme Court of India (Lillu @ Rajesh vs State of Haryana, 2013). Should NOT be performed.
Q28. Hymen - Types and Medico-legal Importance
Hymen: A thin fold of mucous membrane at the vaginal orifice. Highly variable in shape and thickness.
Types:
- Annular (ring-shaped) - most common
- Semilunar (crescentic)
- Cribriform (multiple openings)
- Septate (divided by band)
- Imperforate (no opening) - medical emergency
- Fimbriated (irregular edges)
- Absent (congenitally)
Medico-legal importance:
- Evidence of recent sexual intercourse (fresh tears)
- Tears usually at 5 and 7 o'clock positions (posterior)
- Old healed tears (notches) at 3, 6, 9 o'clock
- Presence/absence of hymen does NOT prove virginity
- Intactness does NOT rule out sexual intercourse (fimbriated, elastic types)
- Absence of tears does NOT mean rape did not occur
Q29. POCSO Act
Protection of Children from Sexual Offences Act, 2012 (amended 2019):
- Protects children (<18 years) from sexual abuse
- Gender-neutral for victims
- Defines: penetrative sexual assault, aggravated sexual assault, sexual harassment, pornography
- Mandatory reporting by any person aware of offence
- Special courts for speedy trial
- Child-friendly procedures
- Death penalty for aggravated penetrative sexual assault on child <12 years (2019 amendment)
Q30. Sodomy - Diagnosis
Sodomy: Anal intercourse (Section 377 IPC - now largely decriminalized for consenting adults by SC in 2018 Navtej Singh Johar case; still an offence when non-consensual or with minors)
Findings in passive partner (acute):
- Lacerations, fissures around anus (6 o'clock most common)
- Congestion, bruising of anal margins
- Bleeding
- Dilatation of anal sphincter
In old cases:
- Funnelling of anus
- Loss of rugae
- Thickening and hyperpigmentation of perianal skin
- Relaxed sphincter
- Lax anus on lateral traction
SECTION 6: MEDICAL JURISPRUDENCE
Q31. Inquest - Types
Inquest: Inquiry or investigation into the cause of death.
Conducted in: Suicide, murder, accident, suspicious death, dowry death, custodial death, deaths under operation/anesthesia.
Two types in India:
1. Police Inquest (Section 194, BNSS / S. 174, CrPC):
- Conducted by sub-inspector or above
- In presence of two panchas
- Prepares panchanama (report with wound description)
- Body sent for PM with dead body challan
- Done in: suicide, accident, killed by animal/machinery, suspicious death
2. Magistrate's Inquest (Section 196, BNSS / S. 176, CrPC):
- Done by District Magistrate / Executive Magistrate
- Mandatory in: dowry death, custodial death (in police/judicial custody), rape victim death, death in a public institution, child death in care
- More detailed; includes witness examination under oath
- Judicial inquest - by coroner (not in India, except certain states historically)
Q32. Dying Declaration
Definition (Section 26(1), BSA / S. 32 IEA): Statement made by a dying person about the circumstances of their death ("Leterm mortem" = words said before death).
Conditions for admissibility:
- Person must believe they are going to die (fear of impending death)
- Must be of sound mind (compos mentis) - doctor certifies
- Must relate to circumstances of their death
- No oath required (dying person presumed to tell truth)
- May be oral or written
Process:
- Executive Magistrate should record it, if time permits
- Doctor certifies mental competence
- Recorded in declarant's own words (no leading questions)
- Read back, signed/thumb impression taken
- If unable to speak: signs/nods recorded as "verbal statement"
Evidentiary value:
- Admissible under BSA Section 26 / IEA Section 32
- Can be sole basis for conviction even without corroboration
- Corroboration increases weight
Q33. Consent - Types and Medical Importance
Informed Consent: A legally valid agreement by a competent patient, after being given adequate information about the procedure, risks, benefits, and alternatives.
Types:
- Express consent: Clearly stated (oral or written)
- Implied consent: Inferred from circumstances (emergency, unconscious patient)
- Informed consent: Patient given full details before consenting
- Proxy consent: By guardian/parent (minors, incompetent)
- Therapeutic privilege: Doctor withholds information if disclosure would harm patient
Valid consent requires:
- Competent individual (adult, sound mind)
- Voluntary (no coercion)
- Adequate information
- Specific to the procedure
Exceptions to consent: Emergency (life-threatening), public health (epidemics), court orders
Q34. Medical Negligence
Definition: Failure of a medical professional to provide the standard of care expected of a reasonably competent practitioner in the same field, resulting in harm to the patient.
Three D's (Essentials):
- Duty of care - doctor-patient relationship established
- Dereliction of duty - breach of standard of care
- Damage - harm resulted
- (Some add 4th D: Direct causation - breach must cause the damage)
Bolam Test (1957): A doctor is not negligent if they acted in accordance with a practice accepted by a responsible body of medical opinion (UK standard, accepted in India).
Civil negligence: Compensation (Consumer Protection Act)
Criminal negligence (S. 304A IPC/BNS): Reckless/gross negligence causing death → imprisonment up to 2 years + fine
Consumer Protection Act: Medical services included (1995 Supreme Court - Indian Medical Association vs VP Shanta); patients are consumers; free government services exempt.
Q35. Dying Declaration vs Dying Deposition
| Feature | Dying Declaration | Dying Deposition |
|---|
| Recorded by | Magistrate, doctor, police, anyone | Magistrate in court |
| Oath | Not administered | Administered |
| Cross-examination | Not allowed | Allowed |
| Legal basis | BSA S. 26 / IEA S. 32 | CrPC provisions |
| Value | Less (no oath) | More (oath + cross-examination) |
Q36. Professional Secrecy
Rule: A doctor must keep patient information confidential.
Exceptions (when secrecy can be broken):
- Court order/subpoena
- Notifiable diseases (plague, cholera, etc.)
- Medicolegal cases - duty to police
- Fitness certificates (employment, driving)
- Public safety (e.g., patient planning harm)
- With patient's consent
- Insurance purposes with consent
Q37. IPC Section 304A (BNS equivalent)
S. 304A IPC (Causing death by negligence):
- "Whoever causes death of any person by doing any rash or negligent act not amounting to culpable homicide..."
- Punishment: Imprisonment up to 2 years, or fine, or both
- Applicable to medical professionals in cases of gross/criminal negligence
SECTION 7: FORENSIC TOXICOLOGY
Q38. Classification of Poisons
Based on action:
- Corrosives: Mineral acids (H2SO4, HCl, HNO3), alkalis (NaOH, KOH), carbolic acid
- Irritants:
- Inorganic: arsenic, antimony, phosphorus, copper sulphate, mercury
- Organic: castor oil, croton oil
- Mechanical: powdered glass
- Neurotropic (Neurotics):
- Cerebral: alcohol, chloroform, ether
- Spinal: strychnine, tetanus toxin
- Peripheral: curare
- Cardiac: Digitalis, aconite, tobacco
- Asphyxiants: CO, HCN
- Miscellaneous: Snake venom, putrefactive poisons
Q39. General Management of Poisoning
Principles (ABCDE):
- Airway - maintain, intubate if needed
- Breathing - O2, ventilation
- Circulation - IV access, fluids, treat shock
- Decontamination:
- Emesis: Syrup ipecac (now rarely used); contraindicated in corrosives, petroleum products, convulsions, unconscious
- Gastric lavage: Within 1-2 hours; saline or KMnO4 (for alkaloids); contraindicated in corrosives
- Activated charcoal: Adsorbs most poisons; given 1 g/kg
- Cathartics: Sorbitol
- Skin/eye decontamination if needed
- Antidote if available
- Enhanced elimination: Dialysis, forced diuresis, urine alkalinization
Q40. Organophosphorus (OP) Poisoning
Examples: Parathion, malathion, methyl parathion, chlorpyrifos, dichlorvos (DDVP)
Mechanism: Inhibit acetylcholinesterase (AChE) enzyme → accumulation of acetylcholine at all cholinergic synapses → overstimulation
Features - SLUDGE (Muscarinic):
- Salivation
- Lacrimation
- Urination
- Defecation
- GI distress (cramps, vomiting)
- Emesis
Additional Muscarinic: Miosis, bronchospasm, bradycardia, hypotension, sweating
Nicotinic features:
- Muscle fasciculations, weakness, paralysis
- Tachycardia (early), hypertension
CNS features:
- Anxiety, restlessness, convulsions, coma
Classic triad: Pin-point pupils (miosis), excessive secretions, muscle fasciculations
Investigation: Serum/plasma cholinesterase levels (reduced <50% of normal is diagnostic)
Treatment:
- Atropine: Large doses; titrated to dry secretions; 2-4 mg IV every 5-10 min until atropinization (dry mouth, dry skin, tachycardia, dilated pupils)
- Pralidoxime (PAM/2-PAM): Reactivates phosphorylated AChE; must give EARLY (before "aging"); dose 1-2 g IV slowly
- Benzodiazepines: For convulsions
- Decontamination: Remove clothing, wash skin
Aging: Irreversible binding of OP to AChE (within hours to days) → PAM useless after aging
Q41. Arsenic Poisoning
Source: Rat poison, pesticides, copper acetoarsenite (Paris green), Fowler's solution
Acute poisoning:
- Garlic odor (smell of arsenic)
- Burning pain in throat and stomach
- Profuse rice-water or bloody diarrhea (cholera-like)
- Severe vomiting, dehydration
- Aldrich-Mees lines (white transverse bands on nails - appear 6 weeks after poisoning)
- Death from dehydration/circulatory collapse
Chronic poisoning (Arsenicosis):
- Peripheral neuropathy (stocking-glove pattern)
- Hyperkeratosis of palms and soles
- Melanosis (rain-drop pigmentation)
- Aldrich-Mees lines on nails
- Alopecia
- Lung and skin cancer (long-term)
Postmortem findings (acute):
- Garlicky odor of body and stomach
- Gastroenteritis pattern
- Liver: fatty change, necrosis
- Kidney: tubular necrosis
- Marsh's test - confirm arsenic in viscera (hydrogen sulphide + arsenic → arsenic mirror)
- Reinsch's test, Reinfeld test
Q42. Alcohol (Ethanol) Poisoning / Drunkenness
Medico-legal aspects of alcohol:
- Legal BAC limit for driving in India: 30 mg/100 mL blood (0.03 g/dL)
Effects at different BAC levels:
| BAC | Effect |
|---|
| 50 mg% | Euphoria, mild impairment |
| 100 mg% | Slurred speech, incoordination |
| 150 mg% | Staggering gait, ataxia |
| 200-250 mg% | Confusion, stupor |
| 300 mg% | Deep stupor |
| 400 mg% | Coma, death possible |
| >500 mg% | Usually fatal |
Signs of drunkenness:
- Smell of alcohol
- Slurred speech (dysarthria)
- Ataxic gait
- Nystagmus
- Flushed face
- Bloodshot eyes
- Disinhibition
Diagnosis:
- Breath analyser (most common)
- Blood alcohol level
- Urine analysis
- Breathalyser (Alcometer)
Denatured alcohol (methanol) poisoning:
- Metabolized to formaldehyde and formic acid
- Features: headache, severe visual disturbance, "snowstorm vision," blindness (optic nerve damage), metabolic acidosis, death
- Treatment: IV ethanol (competitive inhibition), fomepizole, dialysis
Q43. Dhatura (Datura) Poisoning
Plant: Datura stramonium (jimsonweed); contains atropine, hyoscyamine, scopolamine
Features (Anticholinergic syndrome - "Mad as a hatter, hot as a hare, dry as a bone, red as a beet, blind as a bat"):
- Mad: Hallucinations, delirium, confusion
- Hot: Hyperthermia (dry skin, can't sweat)
- Dry: Dry mouth, dry skin
- Red: Flushed skin (cutaneous vasodilation)
- Blind: Dilated pupils (mydriasis), blurred vision
Other features: Tachycardia, urinary retention, constipation, absent bowel sounds
Treatment:
- Gastric lavage (if recent ingestion)
- Physostigmine (antidote - cholinergic agent)
- Supportive care
- Benzodiazepines for agitation
Q44. Carbon Monoxide (CO) Poisoning
Source: Incomplete combustion of carbon - car exhaust, charcoal, coal gas, fires in enclosed spaces
Mechanism: CO has 200-250x higher affinity for Hb than O2 → carboxyhaemoglobin (COHb) → impairs O2 delivery → cellular hypoxia
Features:
| COHb % | Features |
|---|
| <10% | Headache |
| 20-30% | Headache, dizziness, nausea, confusion |
| 40-50% | Confusion, tachycardia, syncope |
| >60% | Convulsions, coma |
| >70% | Death |
Classic sign: Cherry-red (carmine-red) discoloration of skin, mucous membranes, blood, and organs - PATHOGNOMONIC
Postmortem findings:
- Cherry-red livor mortis (even in dependent areas)
- Cherry-red blood, muscles, organs
- Petechiae in white matter of brain
- COHb confirmed by spectroscopy, Kunkel's test
Treatment:
- Remove from source
- 100% O2 by mask (reduces CO half-life from 5 hours to 60 min)
- Hyperbaric O2 (reduces half-life to 20 min) - for severe cases
Q45. Cyanide (HCN) Poisoning
Sources: Bitter almonds, cassava, gold mining, metal plating, fire smoke (plastics)
Mechanism: Inhibits cytochrome oxidase (Complex IV) → mitochondrial O2 utilization blocked → cells cannot use O2 → histotoxic hypoxia
Features: Bitter almond smell on breath; cherry-red skin (O2 not utilized → venous blood stays bright red); rapid unconsciousness; convulsions; death in minutes
Treatment:
- Amyl nitrite (inhalation), sodium nitrite IV → form methaemoglobin → competes with cytochrome for CN
- Sodium thiosulphate IV → converts CN to thiocyanate (safe)
- Hydroxocobalamin - cobalt binds CN (preferred in UK/Europe)
- Dicobalt EDTA
Q46. Corrosive Acid Poisoning (H2SO4, HNO3, HCl)
Mechanism: Coagulation necrosis of tissues
Features:
- Immediate burning pain in mouth, throat, stomach
- Vomiting (blood-stained; reddish-brown in H2SO4; yellow in HNO3; greenish in HCl)
- Staining of lips and mouth:
- H2SO4: black/brown stains
- HNO3: yellow stains (xanthoproteic reaction)
- HCl: greyish-white stains
- Dysphagia, drooling, hypersalivation
- Perforation of stomach/esophagus (late)
- Death from shock, perforation, stricture
Treatment:
- Do NOT induce vomiting
- Do NOT use carbonate antacids (CO2 gas risks perforation)
- Milk/water dilution (aluminium hydroxide gel)
- Morphine for pain
- Stricture prevention (long-term)
Q47. Opium/Morphine Poisoning
Classic Triad:
- Pin-point pupils (miosis)
- Respiratory depression (Cheyne-Stokes or slow, shallow breathing)
- Coma (loss of consciousness)
Other features: Bradycardia, hypotension, cyanosis, flushed skin, dry mouth, constipation, urinary retention
Treatment:
- Airway and ventilation
- Naloxone (opioid antagonist) IV/IM: 0.4-2 mg; repeat every 2-3 min; titrate to respirations
- May need infusion (naloxone half-life shorter than most opioids)
Q48. Snake Bite Management
Types of Indian snakes:
| Snake | Venom Type | Features |
|---|
| Cobra, Krait | Neurotoxic | Ptosis, diplopia, respiratory paralysis |
| Viper (Russell's, saw-scaled) | Haemotoxic | Bleeding, coagulopathy, renal failure |
| Sea snake | Myotoxic | Myoglobinuria, muscle paralysis |
Management:
- Immobilize limb, keep below heart level
- Pressure immobilization bandage (for neurotoxic only)
- Remove constricting bands
- Do NOT: cut and suck, tourniquet (arterial), local incision
- Polyvalent anti-snake venom (ASV): Only specific treatment; given IV; test dose first; watch for anaphylaxis
- Neostigmine + atropine: for neurotoxic bites
- Heparin/fresh frozen plasma: for coagulopathy (haemotoxic)
SECTION 8: FORENSIC PSYCHIATRY
Q49. Section 84 IPC / BNS - Unsoundness of Mind
Section 84 IPC (McNaughton Rules codified):
"Nothing is an offence done by a person who, at the time of doing it, by reason of unsoundness of mind, is incapable of knowing:
(a) the nature of the act, OR
(b) that what he is doing is either wrong or contrary to law."
Burden of proof: On accused to prove insanity on balance of probabilities.
Q50. McNaughton's Rules (1843)
Established after Daniel McNaughton shot Edward Drummond (believing him to be PM Peel).
Rules:
- Every man is presumed sane until proved otherwise
- To establish insanity defense, it must be proved that at time of act, defendant was laboring under a defect of reason from a disease of the mind
- Due to this disease, he did not know the nature and quality of the act, OR
- If he did know, he did not know what he was doing was wrong
Criticism: Does not cover emotional/volitional disorders (irresistible impulse)
Q51. Testamentary Capacity
Definition: Legal capacity to make a valid will.
Requirements (as per Evidence Act/court standards):
- Know the nature of the act (making a will)
- Know the extent of his property
- Know the natural objects of his bounty (family members)
- Understand the claims of those who might expect to benefit
- Not suffering from disorder of mind that would poison his affections, pervert his sense of right, or prevent exercise of natural faculties
Q52. Delirium Tremens
- Acute, severe alcohol withdrawal syndrome
- Onset: 48-96 hours after last drink
- Features:
- Tremors
- Hallucinations (visual most common - seeing pink elephants, insects)
- Agitation, confusion
- Tachycardia, hypertension, fever, sweating
- Seizures (may precede DT)
- Treatment: Benzodiazepines (lorazepam/diazepam), thiamine, IV fluids, monitoring
SECTION 9: MISCELLANEOUS HOT TOPICS
Q53. Brain Death - Criteria
Definition: Irreversible cessation of all functions of the entire brain, including the brainstem.
Preconditions:
- Patient in deep coma (GCS 3)
- Cause known and irreversible
- Exclude: drugs, hypothermia (<35°C), metabolic/endocrine causes
Clinical criteria (all must be present):
- No spontaneous breathing (Apnoea test: PaCO2 must rise to >60 mmHg with no respiratory effort)
- No pupillary response to light (both pupils)
- No corneal reflex
- No oculocephalic reflex (doll's eye)
- No oculovestibular reflex (caloric test)
- No gag/cough reflex
- No motor response to supraorbital pressure
Confirmatory tests: EEG (isoelectric), cerebral angiography, transcranial Doppler
Legal status in India: Transplantation of Human Organs Act, 1994 - brain death declared by a panel of 4 doctors (including neurologist/neurosurgeon and hospital in-charge)
Q54. Euthanasia
Definition: Deliberate act to end life to relieve suffering.
Types:
| Type | Description |
|---|
| Active | Direct action to cause death (lethal injection) |
| Passive | Withdrawal of treatment |
| Voluntary | Patient requests it |
| Non-voluntary | Patient unable to express wish (coma) |
| Involuntary | Against patient's will |
Legal status in India:
- Active euthanasia: Illegal (punishable as murder under IPC)
- Passive euthanasia: Legally allowed - Supreme Court in Aruna Shanbaug case (2011) permitted passive euthanasia under strict guidelines
- Living will / Advance Directive: Upheld by SC in Common Cause vs Union of India (2018) - a person can write advance directive to refuse treatment
Q55. Dowry Death (Section 304B IPC/BNS)
Definition: Death of a woman within 7 years of marriage, caused by burns, bodily injury, or under suspicious circumstances, in connection with demands for dowry.
Punishment: Minimum 7 years imprisonment (up to life)
Section 498A IPC/BNS: Cruelty by husband/relatives - imprisonment up to 3 years
Magistrate's inquest is mandatory in all dowry death cases.
Q56. MLC (Medicolegal Case)
Definition: Any case where the attending doctor, after examination, feels that investigations by law enforcement agencies are essential.
MLC situations include:
- Road traffic accidents
- Assault/battery
- Rape, sexual assault
- Suicide/homicide
- Poisoning
- Burns, industrial accidents
- Custodial injuries
- Unnatural death
Duties of doctor at MLC:
- Provide emergency treatment FIRST (treat before formalities)
- Inform police (cannot be refused treatment for lack of police intimation)
- Preserve evidence (injuries, clothing)
- Prepare careful written record
- Collect forensic samples
- Issue MLC certificate
Q57. Duties of Doctor at Scene of Crime / Autopsy
- Do not disturb evidence
- Certify/confirm death
- Estimate time since death
- Note position and condition of body
- Examine ligature marks, wounds, injuries
- Collect trace evidence (fingernail scrapings, hair, fibers)
- Maintain chain of custody
Q58. Chain of Custody (Chain of Evidence)
- Documented record of who collected, handled, transferred, and analyzed evidence
- Ensures integrity and authenticity of forensic evidence
- Any break in chain = evidence may be inadmissible in court
- Each transfer must be documented and signed
Q59. Rule of Nines (Wallace's Rule of Nine) - Burns
Used to estimate Total Body Surface Area (TBSA) burned:
| Region | % TBSA |
|---|
| Head and neck | 9% |
| Each upper limb | 9% |
| Anterior trunk | 18% |
| Posterior trunk | 18% |
| Each lower limb | 18% |
| Perineum/genitalia | 1% |
Palm method: Patient's palm = 1% TBSA (useful for scattered burns)
Lund-Browder chart - more accurate for children (head larger, legs smaller relative to adults)
Q60. Key IPC/BNS Sections for Viva
| Section | Subject |
|---|
| 84 IPC | Unsoundness of mind (insanity defense) |
| 304A IPC | Causing death by negligence |
| 304B IPC | Dowry death |
| 375-376 IPC | Rape and punishment |
| 377 IPC | Unnatural offences (sodomy) - decriminalized for consenting adults |
| 498A IPC | Cruelty by husband/relatives |
| 174 CrPC (194 BNSS) | Police inquest |
| 176 CrPC (196 BNSS) | Magistrate's inquest |
| 32 IEA (26 BSA) | Dying declaration |
| POCSO 2012 | Child sexual offences |
| Consumer Protection Act | Medical services as consumer service |
Note (2023 update): India has replaced IPC with Bharatiya Nyaya Sanhita (BNS), CrPC with BNSS, and IEA with BSA. In viva, mention both old IPC and new BNS sections - examiners may ask either.
Key Mnemonics Summary
| Topic | Mnemonic |
|---|
| OP poisoning (muscarinic) | SLUDGE |
| Anticholinergic (Dhatura) | "Mad, Hot, Dry, Red, Blind" |
| Gustafson's teeth method | ASCPRT |
| Firearm entry wound features | Abrasion collar, Inverted margins, Smaller |
| Asphyxia signs | Tardieu spots, Cyanosis, Congestion, Frothy discharge |
| Three D's of negligence | Duty, Dereliction, Damage |
| McNaughton rules | Nature/quality of act + knowledge of wrong |
Sources: The Essentials of Forensic Medicine & Toxicology, 36th Edition (Reddy, 2026); Parikh's Textbook of Medical Jurisprudence, Forensic Medicine & Toxicology; PC Dikshit Textbook of Forensic Medicine.