Here are the comprehensive chapter-wise notes for Forensic Medicine & Toxicology, referenced to Narayan Reddy (36th ed., 2026), Parikh, and P.C. Dikshit.
FORENSIC MEDICINE & TOXICOLOGY - CRISP CHAPTER-WISE NOTES
Reference: The Essentials of Forensic Medicine & Toxicology - KS Narayan Reddy (36th Ed, 2026); Parikh's Textbook of Medical Jurisprudence; PC Dikshit
CHAPTER 1: MECHANICAL INJURIES
Q1 - ROAD TRAFFIC ACCIDENTS (RTA)
Classification of RTA injuries by mechanism:
| Mechanism | Examples |
|---|
| Primary impact | Pedestrian struck by vehicle - bumper fractures (most common - tibia/fibula) |
| Secondary impact | Body thrown, strikes another surface |
| Tertiary impact | Body rolls on road after fall |
| Crush injuries | Body run over by wheel |
| Occupant injuries | Steering wheel injury, windshield injury, seat-belt injury |
Types of injuries in RTA:
- Pedestrian (most common victim): Bumper fracture (contrecoup fracture of fibula/tibia at bumper height - 45-60 cm in adults, lower in children), brush abrasions, tyre tread marks, degloving injuries
- Driver/Occupant: Steering wheel chest injury (rib fractures, sternal fractures, cardiac contusion), windshield "spider web" laceration, airbag abrasion burns, seat belt syndrome (bruising across chest/abdomen in diagonal pattern, chance fracture of lumbar vertebra)
- Primary impact zone - at bumper height confirms pedestrian vs driver status
Medicolegal duties in RTA:
- Treat patient as a "medicolegal case (MLC)" - assign MLC number
- Inform police immediately (mandatory under MV Act)
- Thorough documentation of all injuries with size, shape, site, nature
- Collect samples: blood alcohol, urine toxicology, blood group
- Preserve clothing as-is (do not destroy medico-legal evidence)
- Record vital signs and consciousness level (GCS)
- Give treatment without waiting for police
- Issue wound certificate/injury certificate
- Cannot refuse treatment even without consent in emergency
- If death occurs, inform magistrate/coroner for inquest
Q5 - FIREARM INJURIES
Classification of Firearms:
A. Smooth bore firearms:
- Shotgun (12 bore most common), musket, pistol (old type)
B. Rifled firearms:
- Pistols, revolvers, rifles, carbines, machine guns
C. By loading mechanism:
- Muzzle loading, Breech loading
D. By action:
- Single shot, Repeating/Magazine, Semi-automatic, Automatic (machine gun)
Entry Wound - Features (Narayan Reddy):
The entry wound has 4 zones (from within outward):
- Central defect (hole from bullet) - punched out, inverted margins
- Contusion ring / bruise collar - bruising from bullet push
- Abrasion collar (grease collar / dirt collar) - most important medicolegal sign; caused by bullet's rotational and forward momentum rubbing against skin edges, depositing grease, lead, lubricant; always present at entry wound; absent at exit
- Tattooing / stippling - blackening and powder marks at close range only
Abrasion collar details:
- Width 1-2 mm
- Composed of: abrasion of skin margin + grease/oil + lead deposits + carbon
- Always present at ENTRY wound; its presence confirms entry vs exit
- Wider if bullet strikes at an angle (oval-shaped with wider edge on trailing side = tells direction of bullet)
Entry vs Stab wound differences:
| Feature | Firearm Entry | Stab Wound |
|---|
| Shape | Round/oval, punched out | Slit-like, boat-shaped |
| Abrasion collar | Present | Absent |
| Margins | Inverted | Cut, clean |
| Size | Equals caliber (±2mm) | Depends on knife width |
| Track | Bullet track with hemorrhage | Narrow slit track |
| Tattooing | May be present | Absent |
| Blackening | May be present | Absent |
Wound Ballistics - Rifled Firearm:
Ranges of firing and wound characteristics:
-
Contact range (muzzle touching skin):
- Star-shaped/cruciate laceration due to gas expansion under skin
- Muzzle impression (contusion ring)
- Gas between skin and bone: "blow back" phenomenon
- Heavy sooting inside wound track; cherry red color of wound edges (CO formation)
- Hard contact on bone: "shored exit" like appearance
-
Close range (up to 15 cm):
- Burning (singeing of hair, scorching)
- Blackening (sooting/smudging) - can be wiped off
- Tattooing/stippling from unburned/partially burned powder particles - CANNOT be wiped off; unique pattern
- Abrasion collar present
-
Medium range (15 cm - 60 cm):
- Tattooing without burning
- Abrasion collar present
-
Long range (>60 cm):
- Only abrasion collar
- No blackening, no tattooing
Wound ballistics of rifled firearm bullet:
- Primary projectile effect: direct tissue destruction by bullet in its path
- Temporary cavity: tissue displaced outward transiently (water content causes pressure wave); maximum at 3x bullet diameter for high velocity weapons
- Permanent cavity: actual wound track
- Fragmentation: bullet fragments cause secondary projectile injuries
- Yaw and tumble: bullet may yaw (wobble) in tissue, causing larger wound track
- Hydrostatic effect: in fluid-filled organs (bladder, heart) - remote injury due to pressure waves
Exit wound characteristics:
- Larger than entry (bullet deforms, picks up tissue)
- Irregular, stellate, lacerated margins (everted)
- No abrasion collar, no burning, no tattooing
- Edges are everted (pushed outward)
Q10 - ABRASIONS
Classification of Injuries (Narayan Reddy):
- Injuries without solution of continuity: Contusion/bruise
- Injuries with solution of continuity: Abrasion, incised wound, stab/puncture wound, laceration, firearm wound, burns
- Injuries to deeper structures: Fracture, dislocation, visceral injury
ABRASION:
Definition: Superficial injury to skin where only epidermis/superficial dermis is damaged due to friction.
Types:
- Scratch/Linear abrasion - by sharp pointed object (thorn, pin, fingernail)
- Graze/Sliding abrasion - skin dragged across rough surface; shows direction of force (tags point in direction of movement); most common in RTA
- Pressure abrasion - perpendicular force; oval/round; e.g., strangulation mark
- Impact abrasion - blunt force impact; may show pattern of object (patterned abrasion)
Age of Abrasion:
- Fresh: Red/red-brown, bleeding/oozing serum
- 12-24 hours: Scab forms (dried serum + RBC)
- 1-3 days: Red scab, margins elevate
- 4-7 days: Brown/yellow scab, starts separating from edges
- 7-12 days: Scab falls off, pink scar remains
- 2-3 weeks: Scar fades, normal skin restored
- Abrasions heal without scar (if superficial)
Medicolegal Importance:
- Confirm ante-mortem nature of injury
- Indicate nature and direction of force (graze)
- Fingermark abrasions indicate assault/strangulation
- Patterned abrasion identifies weapon (e.g., tyre tread)
- Defense abrasions on hands indicate struggle/self-defense
- Indicate site of contact in RTA (bumper height)
- Graze direction helps reconstruct incident
CHAPTER 2: ASPHYXIAL DEATHS
Q3 & Q15 - DROWNING
Definition: Drowning is a form of asphyxia due to aspiration of fluid into air passages, caused by submersion in water or other fluid. (Narayan Reddy)
Types of Drowning:
- Typical (wet) drowning (80-85%): Water inhaled into lungs - fresh water vs salt water differences
- Atypical (dry) drowning (10-15%): No water in lungs; laryngospasm causes asphyxia; common in children, alcoholics
- Secondary drowning (near drowning): Initial survival, later death from pulmonary edema
- Immersion syndrome (vagal inhibition): Sudden cold water contact causes vagal cardiac arrest; no water aspirated
- Shallow water blackout: Hyperventilation before diving causes hypocapnia; person blacks out before CO2 rises to stimulate breathing
Fresh vs Salt water drowning:
| Feature | Fresh water | Salt water |
|---|
| Plasma tonicity | Water absorbed → hemodilution | Water drawn out → hemoconcentration |
| Blood volume | Increased | Decreased |
| Hemolysis | Marked | Mild |
| Electrolytes | Hyponatremia, hyperkalemia | Hypernatremia |
| Mechanism of death | VF (due to K+/electrolyte disturbance) | Pulmonary edema |
Ante-mortem vs Post-mortem drowning features:
| Feature | Ante-mortem (true drowning) | Post-mortem (body thrown into water) |
|---|
| Froth at mouth | Fine, copious, tenacious, white lathery; reappears on wiping | Absent or thin watery fluid; does not reappear |
| Vegetation/material in hands | Clenched (cadaveric spasm) | Absent or loosely placed |
| Cutis anserina (goose skin) | Present | Usually absent |
| Washerwoman's skin | Fine corrugation of hands/feet | Absent or less pronounced |
| Waterlogging of lungs | Present; lungs voluminous, pits on pressure | Absent |
| Diatoms | Present in tissues | Absent |
| Gettler test | Chloride difference | No difference |
| PM staining | Bright pink/cherry red on dependent parts | Normal hypostasis |
Pathophysiology of Asphyxia (Narayan Reddy):
Asphyxia = condition of deficient O2 AND excess CO2 in blood/tissues.
Stages:
- Stage of dyspnea (1 min): Violent inspiratory/expiratory effort; cyanosis starts; BP rises
- Stage of convulsions (1 min): Tonic convulsions; loss of consciousness; bowel/bladder incontinence
- Stage of exhaustion (1 min): Gasping respirations; pupils dilate; flaccidity
- Stage of respiratory failure (1 min): Respiratory center fails first; heart continues to beat 2-5 minutes
- Stage of cardiac failure: Heart stops; death in 4-5 minutes total
Post-mortem signs of asphyxia (general):
- Cyanosis of lips, face, nails
- Petechiae (Tardieu spots) on conjunctivae, serosal surfaces, subpleural
- Congestion of face and viscera
- Fluidity of blood
- Right heart distension
- Pulmonary edema/hemorrhage
- Bloated, congested lungs (overinflation in drowning)
PM Findings in Drowning:
External:
- Froth at mouth/nostrils (fine, copious, tenacious, reappearing)
- Gooseflesh (cutis anserina)
- Washerwoman's hands (maceration/corrugation)
- Vegetation/sand/mud in clenched hands
- PM staining: pink on dependent parts (CO from decomposition)
Internal:
- Lungs: bulky, waterlogged, pit on pressure (emphysema aquosum); pale on surface, waterlogged on cut; Paltauf's hemorrhage (pale, grayish white patchy subpleural)
- Froth in bronchi/trachea
- Stomach: 100-200 mL water (significant sign; ingested before death, not after)
- Diatoms in viscera (lung, bone marrow, brain, kidney)
- Putrefaction: faster in fresh water
Diatom Test (most specific):
- Diatoms = unicellular algae with siliceous shells; survive boiling/acid digestion
- Present in all natural water bodies
- If drowning occurred in water with diatoms, they enter bloodstream via alveoli → bone marrow, kidney, brain
- Procedure: Organs digested in concentrated HNO3/H2SO4 → centrifuge → examine sediment microscopically
- Finding diatoms in bone marrow = DIAGNOSTIC of ante-mortem drowning (bone marrow not contaminated by post-mortem seepage)
- Bone marrow is most reliable site (best preserved from decomposition)
Gettler Test (historical):
- Compares chloride content of right vs left ventricle blood
- Fresh water drowning: left > right (dilution)
- Salt water drowning: right > left (concentration)
- Currently unreliable due to PM blood changes
Samples preserved:
- Blood (cardiac), Urine, Lung tissue, Stomach contents, Liver, Kidney
- Diatom samples: Femur bone marrow, kidney, liver, lung, brain
- Diatoms from water source (for comparison)
- Vaginal swabs (if sexual assault suspected)
CHAPTER 3: POST-MORTEM CHANGES
Q7 & Q11 - PUTREFACTION & POST-MORTEM INTERVAL
Classification of Post-mortem Changes:
A. Immediate changes (somatic death):
- Loss of sensibility/consciousness
- Cessation of circulation/respiration
B. Early changes:
- Cooling of body (Algor mortis) - 1-1.5°C/hour initially
- Post-mortem lividity (Livor mortis) - 2-4 hrs; fixed 8-12 hrs
- Rigor mortis - begins 2-6 hrs; complete 12 hrs; lasts 36-48 hrs
- Primary flaccidity (immediately after death)
- Secondary flaccidity (after rigor resolves)
C. Late changes:
- Putrefaction
- Mummification
- Adipocere formation
- Saponification
- Maceration (in fetus/aquatic bodies)
Putrefaction - Detailed Notes (Narayan Reddy):
Chief agent: Clostridium welchii (produces lecithinase → hemolysis)
Route: Intestinal bacteria enter post-mortem → spread through blood vessels
Sequence of events:
- 1st sign: Greenish discoloration of right iliac fossa (cecum has most bacteria + least blood supply) - begins 24-36 hrs in summer
- Green to black skin discoloration spreading over body
- Marbling/arborescent pattern: green-brown staining of superficial veins (H2S + hemoglobin = sulfhemoglobin)
- Bloating: gas accumulation (H2S, CO2, NH3, methane) → face swollen, genitals distended, body bloated
- Skin blisters with brownish fluid
- Putrefactive odor (H2S + organic acids)
- Liquefaction of tissues
- Maggot activity (blowfly larva: hatches 24 hrs, active 3-5 days cycles)
Estimation of Post-mortem Interval (PMI):
Early methods (most reliable):
-
Algor mortis (body cooling):
- Normal body 37°C, falls at ~1.5°C/hour (first 6 hrs slower, then faster)
- Henssge nomogram: accounts for weight, ambient temperature
- PMI = (37 - rectal temp)/1.5 (simple formula)
- Affected by: clothing, obesity, ambient temp, ventilation, cause of death
-
Rigor mortis:
- 0-3 hrs: Primary flaccidity
- 3-6 hrs: Rigor begins in small muscles (face, jaw, neck)
- 12 hrs: Fully developed (face to trunk to limbs)
- 12-24 hrs: Fully established
- 24-36 hrs: Begins resolving (jaw first)
- 36-48 hrs: Fully resolved (secondary flaccidity)
- Summer: faster onset and resolution
-
Post-mortem lividity (livor mortis):
- 1-2 hrs: Faint pink patches
- 4-6 hrs: Well-developed, not fixed (shifts on turning body)
- 8-12 hrs: Fixed (fails to shift on pressure/turning)
- 12-24 hrs: Fully fixed
- Color: dark purple-red; cherry red in CO/cyanide; pink in cold
Later methods:
4. Putrefaction: Stage of putrefaction gives rough weeks
5. Insect activity (forensic entomology): Blowfly succession patterns give PMI weeks-months
6. Vitreous humor potassium: Rises 1 mEq/L per ~5 hrs - useful up to 120 hrs
7. Gastric contents: Semi-solid (2-4 hrs), liquid (6+ hrs)
8. CSF biochemistry, eye changes
9. Adipocere/mummification: months to years
Tache Noire:
- Brown/black leathery drying of exposed sclera due to evaporation
- Appears within hours if eyes open post-mortem
- Not a sign of injury
Adipocere Formation:
- Conversion of fat to a white/grey, waxy, soap-like substance (saponification)
- Fatty acids + ammonia/water → adipocere
- Requires: moist, warm, anaerobic conditions (buried/submerged bodies)
- Starts: 3-5 weeks; complete: 3-12 months
- Medicolegal importance: preserves body contours; allows post-mortem examination months/years later; wound marks may be preserved
Rigor Mortis - Medicolegal Importance:
- Helps estimate PMI
- Determines position of body at time of death (secondary flaccidity = body moved)
- Cadaveric spasm (instantaneous rigor): forensic importance (clenched weapon/vegetation)
- Rigor preserved in freezing
- Heat stiffening: irreversible (not true rigor)
Cadaveric spasm:
- Instantaneous rigor at moment of death; no primary flaccidity
- Seen in extreme emotional/physical stress at death (drowning, gunshot)
- Forensic significance: confirms AM activity (victim held object)
- Cannot be reproduced post-mortem artificially
Post-mortem staining vs Bruising:
| Feature | PM staining (lividity) | Bruising (contusion) |
|---|
| Color | Purple-red, uniform | Red-blue-yellow (changes with time) |
| Location | Dependent parts | Anywhere |
| Pattern | Diffuse, extensive | Localized |
| Skin surface | Intact | Intact |
| Incision | Blood washes off | Blood in tissue (cannot wash off) |
| Edges | Fade gradually | Sharp margins |
| Microscopy | No tissue damage | Extravasated RBC in tissue |
| Time | Develops post-mortem | Before death (AM) |
CHAPTER 4: SEXUAL OFFENCES
Q13 - MEDICOLEGAL EXAMINATION IN SEXUAL ASSAULT
Objectives of examination (POCSO/IPC 376):
- Establish whether sexual assault occurred
- Document injuries (physical evidence)
- Collect samples (forensic evidence)
- Assess capacity/consent
- Assess intoxication (DFSA - drug facilitated sexual assault)
- Document general condition
General Procedure:
- Informed consent from victim (caretaker if minor)
- Two doctors preferred (1 female if victim is female)
- Police request (Form 16 equivalent)
- Privacy and confidentiality
- Head-to-toe systematic examination
- Use of colposcope where available
- Document in MLC register
Local/Genital Examination (Female):
Hymen:
- Type: annular, crescentic, fimbriated, dentate, septate, imperforate, cribriform
- Fresh tears: with bleeding, raw edges, tender (AM tears within 24-48 hrs)
- Healed tears: smooth, rounded edges, fibrosed (old tears)
- Complete tears: extend to base; incomplete: don't reach base
- Clock positions documented
- Fourchette: posterior commissure tears common in sexual assault
- Rugae of vagina: effaced = sign of repeated intercourse/assault
Other genital signs:
- Erythema, edema, bruising of vulva
- Lacerations of vaginal wall, fourchette
- Periurethral bruising
- Bite marks
- Pubic hair (collected for comparison)
Signs in male victim (anal assault):
- Anal laxity, anal bruising/fissures
- Funnel-shaped anus (repeated assault)
Corroborative Signs of Rape (Narayan Reddy):
- Hymeneal tear (most important)
- Vaginal lacerations
- Extragenital injuries (bite marks, bruises, grip marks)
- Presence of semen/spermatozoa
- STI transmission
- Pregnancy
Specimens to collect:
- Vaginal/cervical swabs (semen, spermatozoa)
- High vaginal swab
- Anal swab (if anal assault)
- Oral swabs
- Blood (DNA, intoxicant, STI screening, blood group)
- Urine (drug screen, especially for DFSA drugs: GHB, Rohypnol, ketamine)
- Fingernail scrapings (attacker's DNA)
- Pubic hair combings
- Head hair (for comparison)
- Clothing (as-is in paper bags - NOT plastic)
- Skin swabs from bite marks/lick marks
DFSA (Drug-Facilitated Sexual Assault) indicators (as in Q13):
- Drowsy/altered consciousness
- Inability to recall events (anterograde amnesia)
- Found in unfamiliar place
- Disinhibited behavior at party
- Drugs to consider: GHB, Rohypnol (flunitrazepam), ketamine, alcohol
CHAPTER 5: GENERAL TOXICOLOGY
Q2 - ORGANOPHOSPHORUS (OPC) POISONING
Diagnosis: Clinical + ChE estimation
Mechanism: Irreversible inhibition of acetylcholinesterase (AChE) → ACh accumulation → overstimulation of muscarinic, nicotinic, and CNS receptors
Classification of OPC compounds (Narayan Reddy):
- Alkyl phosphates: Parathion, Malathion, TEPP, Chlorpyrifos
- Aryl phosphates: Diazinon, Dichlorvos
- Carbamates (similar action): Carbaryl (reversible AChE inhibitor)
Clinical Features - SLUDGE/DUMBELS mnemonic:
Muscarinic (M-receptors - smooth muscle/glands):
- Salivation (excessive), Lacrimation, Urination, Defecation, GI cramps, Emesis (SLUDGE)
- Bradycardia, hypotension, bronchoconstriction, bronchorrhea, miosis (SMALL pupils - characteristic)
Nicotinic (N-receptors - NMJ/autonomic ganglia):
- Muscle fasciculations, weakness, paralysis
- Tachycardia (may override bradycardia)
- Hypertension initially
CNS:
- Anxiety, restlessness, seizures, coma, respiratory failure (central)
Confirmatory diagnosis:
- Plasma pseudocholinesterase (butyrylcholinesterase): Falls first, easier to measure
- RBC AChE (true cholinesterase): More specific but harder to measure
- <25% of normal = diagnostic; <10% = severe poisoning
- Atropine test: If 2 mg IV atropine causes NO tachycardia/dryness of mouth = OPC poisoning likely
Management (Key steps):
- Remove from exposure, decontaminate skin (remove clothing, wash with soap+water)
- ABC, secure IV access, O2
- Atropine (specific antidote for muscarinic effects):
- Initial: 2-4 mg IV, repeat every 5-15 min
- End-point: dryness of secretions (NOT pupil dilation)
- Total: may need 40-100+ mg in severe cases
- Pralidoxime (2-PAM) (reactivates AChE if given within 24-48 hrs before "aging"):
- 1-2 g IV over 15-30 min, then infusion
- NOT in carbamate poisoning
- Benzodiazepines for seizures
- Ventilation if respiratory failure
- Do NOT use morphine, aminophylline, succinylcholine
Q16 - ARSENIC POISONING (Exhumation Case)
Why soil samples?
- Arsenic is a metalloprotein that binds to sulfhydryl groups → preserved in body
- Leaches into surrounding soil
- Soil comparison confirms contamination source (soil arsenic vs body arsenic ratio)
- Must exclude natural arsenic in soil (normal soil arsenic: <10 ppm; near contaminated source: higher)
Post-mortem imbibition:
- Diffusion of hemoglobin (hemolysis products) from blood vessels into surrounding tissues after death
- Causes: false discoloration of organs (mimics AM hemorrhage)
- Forensic importance: can mimic AM contusion; chloride test or histology differentiates
Acute Arsenic Poisoning - Clinical Features:
- Garlic odor on breath/feces
- Metallic taste
- Burning sensation in throat/stomach
- Cholera-like gastroenteritis: projectile vomiting, rice-water diarrhea
- Severe abdominal cramps
- Tenesmus
- Dehydration, circulatory collapse
- Oliguria/anuria
- Convulsions, coma, death
Investigations:
- Urine arsenic (most useful in acute poisoning): >50 mcg/24 hrs = toxic
- Blood arsenic
- Hair arsenic: 1 cm = 30 days (bands = Mees' lines if chronic)
- Reinsch test: Arsenic deposits on copper strip in HCl (screening)
- Marsh test (quantitative): gold standard; arsenic → arsine → deposits as arsenic mirror
- Gutzeit test: screening; arsine turns lead acetate paper yellow-brown
Treatment:
- Gastric lavage with water/milk
- Demulcents (milk, egg white)
- BAL (British Anti-Lewisite = Dimercaprol): chelation; 3-5 mg/kg IM every 4-6 hrs for 2-3 days → then DMSA
- IV fluids, correct electrolytes
- Symptomatic: anti-emetics, anti-diarrheals
Differential Diagnosis of Arsenic Poisoning:
- Cholera (key differences in table)
- Gastroenteritis
- Food poisoning
- Phosphorus poisoning
- Mercury poisoning
Arsenic vs Cholera:
| Feature | Arsenic | Cholera |
|---|
| Odor | Garlic odor | No garlic |
| History | Ingestion of arsenical compound | Epidemic setting, contaminated water |
| Pupils | Dilated | Normal |
| Vomiting | Early, before diarrhea | Diarrhea precedes vomiting |
| Urine | Diminished | Normal initially |
| Detection | Marsh/Reinsch test | Vibrio cholerae culture |
CHAPTER 6: GASEOUS POISONS
Q4 - HYDROGEN SULPHIDE (H2S) POISONING
Diagnosis: History of working in sewers/septic tanks/manhole; characteristic odor (rotten eggs); rapid collapse
Source: Decomposition of organic sulfur compounds, sewers, septic tanks, volcanic gases, industrial (petroleum refining)
Properties: Colorless, heavier than air (accumulates at bottom of pits), highly toxic, rotten egg smell
Mechanism:
- Inhibits cytochrome oxidase (c, a, a3) → blocks mitochondrial electron transport → cellular asphyxia
- Similar to HCN (both inhibit cytochrome oxidase)
- Low doses: irritant to mucous membranes
- High doses (>300 ppm): rapid knockdown/death
Clinical Features:
- Low concentration (< 50 ppm): Eye/nose/throat irritation, headache
- Moderate (50-200 ppm): Nausea, vomiting, dizziness, pulmonary edema
- High (>300-500 ppm): Rapid loss of consciousness, convulsions, "knockdown"
- Very high (>1000 ppm): Instant death ("struck by lightning" appearance)
- Olfactory fatigue (can't smell the gas after continued exposure - dangerous)
Differential Diagnosis:
- CO poisoning (cherry-red skin; CO test)
- HCN poisoning (bitter almond smell)
- OPC poisoning (SLUDGE symptoms)
- Methane (asphyxia without specific toxicity)
- CO2 accumulation in sewers
Management:
- Rescue with self-contained breathing apparatus (SCBA) - rescuer safety first
- Remove victim from exposure
- 100% O2 (high-flow mask or ventilation)
- NO specific antidote (unlike CN where Na thiosulfate/hydroxocobalamin used)
- Hyperbaric O2 in severe cases
- Bronchodilators for bronchospasm
- Treat pulmonary edema
Post-mortem Findings:
- Greenish discoloration of skin and viscera (H2S + hemoglobin = sulfhemoglobin = cherry-green/green)
- Rapid putrefaction
- Lungs: edematous, hemorrhagic
- Blood: chocolate-brown/dark (sometimes greenish due to sulfhemoglobin)
- Garlic/rotten egg odor persisting in tissues
- Brain: congestion, edema
CHAPTER 7: SNAKE BITE
Q6 & Q8 - KRAIT / VIPER / COBRA BITE
Poisonous vs Non-Poisonous Snakes:
| Feature | Poisonous | Non-Poisonous |
|---|
| Head | Triangular, broader than neck | Oval/rounded, not distinct |
| Fangs | Present (front - Elapidae/Viperidae) | No fangs |
| Bite marks | 1-2 fang marks + tooth marks | Multiple rows of small teeth marks |
| Scales (belly) | Large, single | Paired |
| Tail | Uniformly tapers | May be distinct |
| Pit organ | Pit vipers have loreal pit | Absent |
India's Big 4 Poisonous Snakes:
- Common Cobra (Naja naja) - Neurotoxic
- Common Krait (Bungarus caeruleus) - Neurotoxic
- Russell's Viper (Daboia russelli) - Hemotoxic
- Saw-scaled Viper (Echis carinatus) - Hemotoxic
Cobra vs Viper (Narayan Reddy):
| Feature | Cobra | Viper |
|---|
| Head | Small, not broader | Large, triangular |
| Pupil | Round | Vertical (elliptical) |
| Fangs | Short, grooved, fixed | Long, canalized, folding |
| Venom | Neurotoxic | Hemotoxic (cytotoxic + vasculotoxic) |
| Tail | Round | Tapering abruptly |
| Young | Lay eggs (oviparous) | Viviparous |
Krait Bite - Clinical Features:
- Venom: Alpha and beta bungarotoxins - block ACh release at NMJ (presynaptic)
- Bite: nocturnal, often while sleeping; bite may be painless
- Local signs: minimal swelling/bruising (unlike viper)
- Systemic (neurotoxic) signs:
- Descending paralysis: ptosis → ophthalmoplegia → facial palsy → bulbar palsy (dysphagia, dysarthria)
- Respiratory paralysis (main cause of death)
- Abdominal pain, vomiting
- NO significant coagulopathy
- Krait: early bite often seems trivial; patient deteriorates overnight
Viper Bite - Clinical Features:
- Russell's Viper: Hemotoxic + Neurotoxic
- Local: intense pain, swelling, hemorrhagic blister, necrosis
- Systemic: coagulopathy (DIC), spontaneous bleeding (gums, nose, wounds), hematuria, hemoptysis, renal failure
- Saw-scaled viper: Similar but smaller; highly prevalent cause of snakebite death in India
Bedside tests:
- 20-minute Whole Blood Clotting Test (20WBCT): 2 mL blood in clean dry glass tube; leave undisturbed 20 min; if blood clots = venom-induced consumption coagulopathy absent; if no clot = VICC (viper envenomation)
- Urine: hematuria = nephrotoxic envenomation
- Neurological assessment: eyelid ptosis, gag reflex
Neurotoxic vs Hemotoxic (Vasculotoxic) Venom:
| Feature | Neurotoxic (Cobra, Krait) | Hemotoxic (Viper) |
|---|
| Mechanism | NMJ block, Na+ channel block | Phospholipase, hyaluronidase, coagulopathy |
| Local signs | Minimal | Severe swelling, necrosis |
| Paralysis | Yes (descending) | Absent |
| Bleeding | No | Yes (DIC, spontaneous) |
| Renal failure | Rare | Common |
| 20WBCT | Clots | Does NOT clot |
| Treatment priority | Ventilation | FFP/Anticoagulation |
Management of Snake Bite:
First aid (do's and don'ts):
- Immobilize bitten limb (splint)
- Pressure immobilization bandage (PIB) for neurotoxic only (NOT for viper)
- Remove rings/watches
- Transport rapidly to hospital
- DO NOT: tourniquet, incision, suction, electric shock, herbal remedies
Hospital management:
- ABC, IV access
- Anti-snake Venom (ASV):
- Polyvalent ASV covers all Big 4
- Indications: coagulopathy (20WBCT positive), neurotoxicity, renal failure, local necrosis
- Dose: 8-10 vials IV (may need 20+ in severe envenomation)
- Test dose: 0.1 mL SC (or omit - WHO advises against)
- Repeat if symptoms persist
- Supportive: intubation/ventilation for respiratory paralysis
- Fresh Frozen Plasma (FFP)/whole blood for coagulopathy
- Neostigmine + atropine for cobra envenomation (helps reverse NMJ block partially)
- Tetanus prophylaxis
- Antibiotics (wound infection)
- Watch for anaphylaxis to ASV
CHAPTER 8: INORGANIC POISONS
Q9 - ALUMINIUM PHOSPHIDE (AlP) POISONING
Diagnosis: History of ingesting grain preservative (Celphos/Phostoxin/Quickphos tablets); blood-stained froth at mouth; garlicky/rotten fish odor (phosphine gas)
Mechanism:
- AlP + moisture/HCl (stomach acid) → Phosphine gas (PH3) + Al(OH)3
- Phosphine inhibits cytochrome oxidase → cellular asphyxia
- Direct corrosive effect on GI mucosa
- Causes free radical damage
Clinical Features:
- Onset: 30 min - few hours after ingestion
- Garlic/phosphine (rotten fish) odor in breath
- Nausea, vomiting, epigastric pain
- Hematemesis (corrosive effect)
- Blood-stained froth from mouth/nostrils
- Cardiovascular collapse: refractory hypotension (direct myocardial toxicity)
- Pulmonary edema, ARDS
- Metabolic acidosis
- Hepatic/renal failure
- Death: within hours to days
PM Findings:
- Garlicky/phosphine odor (opens in ventilated area - forensic pathologist risk!)
- Corroded gastric mucosa (black, hemorrhagic)
- Pulmonary edema
- Myocardial damage
- Hepatic necrosis
Samples preserved:
- Stomach contents (sealed airtight container in refrigerator - prevent PH3 escape)
- Blood, urine, liver, kidney, lung
- Silver nitrate paper test (blackens in PH3) done at autopsy
Management:
- NO specific antidote
- Gastric lavage with potassium permanganate (0.1% KMnO4) or coconut oil (phosphine not water-soluble)
- Activated charcoal
- Magnesium sulfate (prevents conversion of AlP → phosphine in gut)
- Supportive: pressor agents (dopamine/noradrenaline), O2, treat pulmonary edema
- IV steroids (for membrane stabilization)
- Do NOT use gastric lavage with water (accelerates phosphine release)
- Prognosis: Poor; mortality >70% in severe cases
CHAPTER 9: VEGETABLE POISONS
Q12 - DATURA POISONING
Datura (Dhatura / Jimsonweed / Angel's trumpet / Devil's apple)
Active Principles (Belladonna alkaloids):
- Hyoscine (Scopolamine) - primary CNS agent; causes delirium more than atropine
- Hyoscyamine - potent anticholinergic
- Atropine (DL-hyoscyamine)
All parts of plant contain alkaloids; seeds have highest concentration
Fatal Dose: Seeds: 10-100 (variable); Alkaloids: ~10 mg hyoscine
Fatal Period: 24-36 hours
Mechanism: Competitive antagonism at muscarinic ACh receptors (anti-SLUDGE effect)
Clinical Features - "Mad as a hatter, Hot as a hare, Dry as a bone, Red as a beet, Blind as a bat":
- CNS: Restlessness, delirium, hallucinations (lilliputian hallucinations - characteristic), excitement, rambling speech, convulsions, positive Babinski sign
- CVS: Tachycardia (increased HR), increased BP
- Eyes: Mydriasis (dilated pupils) - classic; blurred vision
- Skin: Dry, hot, flushed (red face)
- Glands: Complete dryness - dry mouth, no sweating, no tears
- Temperature: Hyperthermia
- Drunken gait (cerebellar effect)
Management:
- Gastric lavage with 0.2% KMnO4 or 2% NaHCO3
- Activated charcoal
- Physostigmine (eserine): specific antidote; 1-3 mg IM/slow IV; crosses BBB; reverses CNS signs
- Diazepam for seizures
- Cooling measures for hyperthermia
- Urinary catheter (urinary retention)
- Dark room (photophobia due to mydriasis)
- IV fluids
Medicolegal Aspects:
- Used for robbery (mixing with food/drink) - "Datura robbery"
- Used in homicide (dacoity cases)
- Religious/ritual misuse
- Malingering (self-administration to fake illness)
- Datura alkaloids detected in urine by immunoassay/chromatography
- Can be used as date rape drug (produces amnesia/confusion)
CHAPTER 10: NARCOTIC POISONS
Q14 - OPIUM POISONING
Diagnosis: Classic triad = Pin-point pupils + Coma + Respiratory depression
Active Principles of Opium:
- Morphine (10%): most important
- Codeine (0.5%)
- Heroin (diacetylmorphine) - synthetic derivative
- Papaverine, noscapine, thebaine
Fatal Dose: Morphine: 0.2-0.3 g (oral), 0.06-0.1 g (IV)
Fatal Period: 6-12 hours
Mechanism: Agonist at mu (μ), kappa (κ), delta (δ) opioid receptors → CNS depression, respiratory depression, analgesia
Clinical Features (Narayan Reddy):
- Triad: Pin-point pupils (miosis due to Edinger-Westphal nucleus stimulation), coma, respiratory depression
- All secretions suspended EXCEPT sweat (profuse sweating - paradox)
- Skin cold and clammy
- Slow, stertorous (snoring) respirations
- Low BP, slow full pulse (bradycardia)
- Peculiar sweet/narcotic odor of breath
- Pupils: constricted, do NOT react to light
- Reflexes: depressed/absent
- Cyanosis (late, due to respiratory failure)
- Death: respiratory failure
Differential Diagnosis:
| Feature | Opium | Barbiturate | Alcohol |
|---|
| Pupils | Pin-point | Dilated/normal | Variable |
| Respiration | Slow, stertorous | Slow | Variable |
| Odor | Sweet/narcotic | None | Alcohol |
| Response to Naloxone | Yes | No | No |
| Sweating | Profuse | Absent/variable | Profuse |
| Reflexes | Depressed | Absent in deep coma | Variable |
Management:
- ABC, oxygen, intubation/ventilation if needed
- Gastric lavage (if oral, within 1-2 hrs; use 0.05% KMnO4)
- Naloxone (Narcan): Specific opioid antagonist
- 0.4-2 mg IV, repeat every 2-3 min up to 10 mg
- Short half-life: may need repeat doses or infusion
- Reverses coma, miosis, respiratory depression rapidly
- Diuresis
- Supportive: vasopressors, warming
Medicolegal Significance:
- Accidental overdose (IV drug users)
- Homicide (child murder with opium)
- Suicide
- Drug dependency/addiction
- Sign of addiction: needle tracks, thrombosed veins, skin abscesses
- Naloxone challenge test (precipitation of withdrawal)
- Neonatal withdrawal (baby of addicted mother)
SHORT ANSWER NOTES (Organized by Category)
FORENSIC PSYCHIATRY & MENTAL HEALTH
Hallucination: False sensory perception without external stimulus; real quality to patient; types - auditory (most common in schizophrenia), visual (organic/delirium), olfactory (temporal lobe epilepsy), tactile (cocaine bug), gustatory. Distinguish from illusion (distorted real perception) and pseudo-hallucination (no external stimulus + patient knows it's unreal).
Delusions: False, fixed, firmly held belief that is not amenable to reason, inconsistent with patient's cultural background. Types: persecutory, grandiose, nihilistic, somatic, erotic (Erotomania), Fregoli, Capgras, reference, control. Classified: primary (autochthonous) and secondary (mood-congruent).
Magnan's syndrome: Cocaine psychosis; characterized by formication (insects crawling under skin = cocaine bug/Ekbom syndrome), paranoid delusions, visual/tactile hallucinations; seen in chronic cocaine use. Magnan also described symptoms in chronic alcoholism with hallucinations.
Munchausen syndrome by proxy (Factitious Disorder Imposed on Another - FDIA): Caregiver (usually mother) fabricates/induces illness in child to gain medical attention; form of child abuse; forensic importance: child death, pattern recognition, covert video surveillance in hospital.
Transvestism: Wearing clothes of opposite sex; may be fetishistic (sexual arousal) or identity-based; differentiate from transsexualism (gender identity disorder) and drag.
Narcoanalysis: IV injection of hypnotic/barbiturate (Na thiopental 0.2-0.3 g or Na amytal) to create half-conscious state to elicit information; NOT reliable (subject may fabricate under influence); SC ordered in India: Selvi vs State of Karnataka 2010 - narcoanalysis cannot be forcibly administered (violates Art. 20(3) - right against self-incrimination).
Drug addiction vs habituation (WHO):
| Feature | Addiction | Habituation |
|---|
| Craving | Overwhelming, compulsive | Mild desire |
| Dependence | Psychological + Physical | Psychological only |
| Tolerance | Marked | Little/none |
| Withdrawal | Severe physical symptoms | None/mild |
| Harm | Self and society | Primarily self |
| Examples | Heroin, alcohol, cocaine | Tobacco, caffeine |
Solvent abuse (inhalant abuse): Deliberate inhalation of volatile solvents (glue, petrol, aerosols, paint thinners); common in street children; causes euphoria, dizziness, hallucinations; acute toxicity: sudden sniffing death (cardiac arrhythmia); chronic: brain damage, hepatic/renal damage.
Right-Wrong test (M'Naghten rules): Legal test of criminal insanity; person not guilty if: at time of act, due to defect of reason from disease of mind, they did not know nature/quality of act OR did not know it was wrong. Forensic: establishes if accused knew difference between right and wrong.
Intersex: Individual with discordance between chromosomal, gonadal, or phenotypic sex. Types: True hermaphrodite (both ovarian + testicular tissue), Pseudohermaphrodite (gonad of one sex + external genitalia of other). Causes: CAH, androgen insensitivity syndrome, Turner's, Klinefelter's. Medicolegal: gender assignment, legal sex.
MEDICAL JURISPRUDENCE & LEGAL CONCEPTS
Vicarious liability: A person held legally responsible for actions of another (e.g., employer for employee's actions). In medicine: hospital for acts of its employed doctors; senior doctor for acts of junior under supervision. Principle: "respondeat superior."
Privileged communication: Information disclosed in confidence in a professional relationship that cannot be revealed without consent. Doctor-patient = absolute privilege in some jurisdictions; but doctor MUST disclose if required by law (notifiable diseases, court orders, public safety) - qualified privilege.
Testamentary capacity: Legal competence to make a valid will. Requirements: must know nature of making a will; know extent of property; know natural claimants; have no mental disorder affecting decision. Doctor may certify fitness to make will in case of doubt.
IPC Section 320 - Grievous Hurt (8 types):
- Emasculation
- Permanent loss of sight of either eye
- Permanent loss of hearing of either ear
- Deprivation of any member or joint
- Destruction/permanent impairing of powers of any member or joint
- Permanent disfiguration of head or face
- Fracture or dislocation of bone or tooth
- Any hurt which endangers life or causes severe bodily pain/inability to follow ordinary pursuits for 20+ days
IPC Section 375 - Rape: Sexual intercourse by man with woman without consent OR with consent obtained by fear/deceit/intoxication/insanity. Age of consent = 18 years. Penetration (however slight) = sufficient. Marital rape not recognized in India (wife >15 yrs).
IPC Section 84: Not guilty if at time of act, by reason of unsoundness of mind, incapable of knowing nature of act OR that it was wrong/contrary to law. (= Indian equivalent of M'Naghten rules)
Medicolegal importance of age: Determines criminal responsibility (7 yrs = doli incapax, 12-18 = juvenile), marriage age, consent, MTP eligibility, POCSO, testamentary capacity, pension, employment. Doctors estimate age by physical examination: bone age (X-ray), dental age, secondary sexual characteristics.
Informed consent: Valid consent must be: voluntary, competent patient, adequate information given, understandable. Components: diagnosis, proposed treatment, risks, benefits, alternatives, right to refuse. Written consent preferred for surgery. EXCEPTIONS: emergency, therapeutic privilege, waiver, public health.
Res ipsa loquitur: "The thing speaks for itself"; negligence inferred from the nature of the event without specific proof; e.g., surgical instrument left inside patient, wrong limb amputated.
Subpoena/Summons: Court order requiring person to appear as witness; failure = contempt of court. Conduct money: fee paid to witness to cover travel expenses for court appearance.
Documentary evidence: Written/recorded evidence submitted to court; includes MLC records, post-mortem reports, radiology images, audio/video recordings; must be authenticated.
Inquest: Inquiry into the cause of sudden/unnatural/suspicious death. Types: Police inquest (Sec 174 CrPC), Magistrate's inquest (Sec 176 CrPC), Coroner's inquest (in some states).
Exhumation: Legal disinterment of a buried body for medicolegal examination. Requires: magistrate's order; done in presence of magistrate/police; exhuming doctor should not be same as original PM doctor; samples from surrounding soil taken (arsenic detection); body re-interred after.
IDENTIFICATION & FORENSIC ANTHROPOLOGY
Dactylography (fingerprint science): Study of fingerprints for identification. Based on: uniqueness (no two persons identical), permanence (unchanged from 3rd fetal month to decomposition).
Fingerprint patterns:
- Loops (most common ~65%): Ridges enter one side, loop, exit same side; ulnar or radial
- Whorls (~30%): Circular/spiral pattern; two deltas
- Arches (~5%): Ridges sweep from one side to other; plain or tented arch
- Composites (rare): Combination patterns
Galton-Henry classification: India uses modified Henry system.
Cheiloscopy: Study of lip print patterns for identification; unique like fingerprints; used in forensic identification.
Superimposition: Technique overlaying skull with ante-mortem photograph to confirm identity. Photographic superimposition or video superimposition. Narayan Reddy popularized this method.
Sex differences - Pelvis:
| Feature | Male | Female |
|---|
| Overall | Heavy, rugged | Light, smooth |
| Subpubic angle | <90° (V-shape) | >90° (wide arch) |
| Pelvic inlet | Heart-shaped | Oval/circular |
| Sacrum | Long, narrow, curved | Wide, less curved |
| Obturator foramen | Oval | Triangular |
| Acetabulum | Large | Small |
| Ischial spines | Prominent | Non-prominent |
Sex differences - Skull:
| Feature | Male | Female |
|---|
| Size | Larger | Smaller |
| Mastoid process | Large | Small |
| Supraorbital ridges | Prominent | Smooth |
| Forehead | Low, sloping | High, rounded |
| Cranial capacity | ~1450 mL | ~1300 mL |
| Chin | Square, rugged | Pointed, smooth |
Human vs Animal hair:
| Feature | Human | Animal |
|---|
| Medulla | Narrow (<1/3 diameter), fragmented | Wide (>1/2 diameter), continuous |
| Cuticle scales | Flat, narrow | Broad, petal-shaped |
| Cross section | Oval | Varies |
| Pigment | Peripheral (cortex) | Central |
| Shaft | Uniform | Varies |
REPRODUCTIVE HEALTH, SEXUAL OFFENCES & MTP
MTP Act 1971 (amended 2021):
- Termination up to 20 weeks (1 registered medical practitioner)
- Up to 24 weeks for special categories: survivors of sexual assault, rape, incest; minors; married women (contraceptive failure); women with physical/mental disability
- Beyond 24 weeks: Medical Board decision only (for fetal abnormality incompatible with life or risk to life of mother)
- Pregnancy of minor: Opinion of 2 doctors required up to 20 wks; can go to Medical Board for >20 wks
- Confidentiality: Doctor cannot reveal identity of woman to anyone except required by law
Natural vs Criminal Abortion:
| Feature | Natural (Spontaneous) | Criminal (Illegal) |
|---|
| Intention | None | Deliberate |
| Cause | Medical/genetic | Abortifacient/trauma |
| Uterus | Signs of disease | Signs of interference |
| Cervix | Natural changes | Trauma, foreign body marks |
| PM evidence | Fever, sepsis only if infected | Instrument marks, perforations |
| Legal | Not criminal | IPC 312-316 |
Abortifacient drugs: Ergot, quinine (large doses), pennyroyal oil, slippery elm, oxytocin, prostaglandins (used illegally), misoprostol (legal if prescribed), RU-486 (mifepristone + misoprostol - legal).
Signs of liveborn child (Narayan Reddy):
- Pulmonary air entry: lungs float in water (hydrostatic test positive)
- Air in GI tract (stomach, intestines)
- Change in umbilical vessels (obliteration begins after birth)
- Respiratory changes in lungs (aerated alveoli on histology)
- Presence of meconium in lower bowel (discharged after birth)
- Food/milk in stomach
- Vivianite stain in meconium absent (if already passed)
Hydrostatic test (Breslau second life test):
- Lungs placed in water: FLOAT = air present = lived and breathed (positive)
- Sink = no air = stillborn or macerated (negative)
- False positive: putrefaction (gas in lungs)
- False negative: pneumonia, meconium aspiration
Signs of stillborn vs dead-born fetus:
- Stillborn: born dead at ≥28 weeks; shows partial maceration; lungs collapsed
- Deadborn/macerated: died in utero; overlapping skull bones, skin peeling
Causes of impotency/sterility in males:
- Impotency: failure of erection/ejaculation. Causes: psychological, vascular, neurological, hormonal, drug-induced, anatomical
- Sterility: inability to fertilize. Causes: azoospermia (primary/secondary), obstructive (post-infection), hormonal (hypogonadism), varicocele, genetic (Klinefelter's)
Bestiality: Sexual act between human and animal; IPC Section 377 (unnatural offences).
Surrogacy (Regulation) Act 2021: Altruistic surrogacy only (no commercial); surrogate must be close relative; married heterosexual couple only; single parents: widowed/divorced only.
TOXICOLOGY SHORT NOTES
Gastric lavage:
- Indications: ingestion of poison within 1-2 hours (or up to 4-6 hrs for some)
- Technique: patient in left lateral position, 16-18 Fr Ewald tube, 200-300 mL aliquots, total 5-10 litres, warm water/saline
- Contraindications: corrosive poisoning (strong acid/alkali), hydrocarbon ingestion (aspiration risk), comatose patient without protected airway, esophageal varices, convulsing patient, bleeding disorders
Burtonian line (Lead line): Bluish-black stippled line along gum margin due to lead sulfide deposition; seen in chronic lead poisoning (plumbism); gum must be infected for it to appear.
Plumbism (Chronic Lead Poisoning):
- Burton's line, peripheral neuropathy (wrist/foot drop), anemia (basophilic stippling), abdominal colic (lead colic), encephalopathy, nephropathy
- Treatment: EDTA chelation, DMSA (oral), BAL
Botulism:
- Clostridium botulinum toxin; blocks ACh release at NMJ (presynaptic)
- Types: food-borne, wound, infant, iatrogenic
- Clinical: descending flaccid paralysis, diplopia, dysphagia, respiratory failure; NO fever, NO sensory loss; pupils dilated (unlike krait)
- Treatment: antitoxin, supportive, ventilation
Ergot poisoning:
- Caused by ergot alkaloids (ergotamine, ergotoxine) from Claviceps purpurea on rye
- Features: vasoconstriction → gangrenous ergotism (St. Anthony's Fire: burning pain, dry gangrene), convulsive ergotism (fits, hallucinations)
- Medicolegal: historically used as abortifacient
Cannabis preparation:
- From Cannabis sativa (hemp plant)
- Preparations: Bhang (dried leaves/stems - weakest), Ganja (flowering tops - moderate), Charas/Hashish (resin - strongest), Hash oil (most concentrated)
- Active principle: Delta-9-tetrahydrocannabinol (THC)
- Schedule I drug in India; NDPS Act 1985
Body packer syndrome: Smuggling drugs by swallowing wrapped packets (cocaine, heroin); packets rupture → massive fatal overdose; X-ray/CT abdomen shows packets; management: conservative if asymptomatic; surgery if rupture/obstruction.
Strychnine poisoning vs Tetanus:
| Feature | Strychnine | Tetanus |
|---|
| Onset | Minutes after ingestion | Days-weeks (incubation) |
| Trismus (lockjaw) | Usually absent initially | Early prominent sign |
| Between convulsions | Complete relaxation | Some rigidity persists |
| Consciousness | CLEAR between fits | Clear |
| Risus sardonicus | May occur | Classic |
| Treatment | Sedation, muscle relaxants | Antitoxin, penicillin, sedation |
| History | Poison ingestion | Wound, no vaccination |
BURNS, INJURIES & TRAUMA
Rule of Nines (Wallace):
- Head + Neck = 9%
- Each arm = 9% (x2 = 18%)
- Chest (anterior) = 9%, Abdomen (anterior) = 9%
- Upper back = 9%, Lower back = 9%
- Each thigh = 9%, Each leg = 4.5%
- Perineum = 1%
- Total = 100%
- For children: Lund-Browder chart (head proportionally larger)
Ante-mortem vs Post-mortem burns:
| Feature | Ante-mortem | Post-mortem |
|---|
| Vital reaction | Present (redness, blistering, WBC) | Absent |
| Blister fluid | Protein-rich, inflammatory cells | Serous/gas only |
| Carbon in airway | Present (inhaled smoke) | Absent |
| COHb in blood | >10% | Absent |
| Pugilistic attitude | May be present | Present (heat coagulation) |
| Heat ruptures | Less frequent | Common (splits) |
| CO analysis | Positive (blood) | Negative |
Joule burns (electrical burns):
- Entry wound: charred, leathery, cup-shaped depression; pale center, red margin
- Exit wound: larger, more explosive; "blow-out" appearance
- Crocodile skin appearance (electrical mark)
- Clothing may be burnt or intact depending on resistance
- May produce metallic deposit from wire/current source
Filigree burns (lightning): Arborescent (fern/tree-like) erythematous pattern on skin from lightning; due to flashover effect; Lichtenberg figures; pathognomonic of lightning injury.
Counter-coup injury: Brain injury opposite to site of impact; occurs in head injuries; most severe coup at impact site + counter-coup opposite; common in moving head hitting stationary object.
Skull fracture types:
- Linear (most common)
- Comminuted (stellate/spider-web)
- Depressed (localized force)
- Diastatic (along suture line; seen in infants)
- Pond fracture (infant skull - indentation without break)
- Ring fracture (basal skull around foramen magnum)
Signs of head injury:
- Battle's sign (bruising over mastoid)
- Raccoon eyes (periorbital ecchymosis)
- CSF rhinorrhea/otorrhea
- Hemotympanum
- Lucid interval (extradural hematoma - classic)
- GCS deterioration
FORENSIC PATHOLOGY & AUTOPSY
Virtual autopsy (Virtopsy): Non-invasive post-mortem examination using CT/MRI ± angiography ± photogrammetry; detects fractures, pneumothorax, hemorrhage, foreign bodies (bullet), gas; limitations: cannot assess decomposing tissue or chemical poisoning; developed by Prof. Michael Thali (Bern).
Negative autopsy: Post-mortem examination reveals no anatomic/toxicological cause of death; seen in: sudden cardiac death (electrophysiological), epilepsy, SIDS, some cases of smothering, drug toxicity with no visible change.
Immersion syndrome: Sudden death in cold water due to vagal inhibition (cardiac arrest) from stimulation of cold receptors; no water in lungs; no asphyxia; = dry drowning variant.
Cafe coronary: Sudden death due to choking on food bolus impacted at glottis/larynx; no heart disease; common in intoxicated/elderly/denture wearers; Heimlich maneuver is first aid.
Burking: A method of homicidal asphyxia; combination of smothering + traumatic asphyxia; compression of chest + occlusion of mouth/nose; no marks visible; named after William Burke (1828).
Battered baby syndrome (Non-accidental injury/child abuse):
- Multiple injuries of different ages
- Metaphyseal fractures, spiral fractures
- Subdural hematoma, retinal hemorrhage (shaken baby)
- Bruises in unusual locations
- Skin burns, bite marks
- Discrepancy between history and injury pattern
Casper's Dictum: Rate of putrefaction ratio - 1 week in air = 2 weeks in water = 8 weeks in soil (regarding rate of decomposition).
BALLISTICS & FIREARMS
Shotgun cartridge components (from base to top):
- Brass head/base (primer cup at base center)
- Propellant powder (gunpowder/smokeless)
- Wad (felt/cardboard - separates powder from shot)
- Shot pellets (multiple lead balls in 12-bore) or single slug
- Crimped/sealed plastic/paper hull (mouth sealed)
- Caliber designated by bore (gauge)
Tandem bullet: Two bullets loaded in one cartridge chamber; front bullet pushes second; creates unusual wound patterns; one or both may travel; used in some homicides to confuse investigation.
MISCELLANEOUS FORENSIC & MEDICAL CONCEPTS
Coma cocktail: Empirical IV treatment for coma of unknown cause: (1) 50% Dextrose 50 mL IV (hypoglycemia), (2) Thiamine 100 mg IV (Wernicke's; give BEFORE glucose), (3) Naloxone 0.4-2 mg IV (opioid reversal), (4) Flumazenil 0.2-1 mg IV (benzodiazepine reversal - use cautiously).
Lucid interval: Period of apparent recovery/consciousness between head injury and subsequent deterioration; classic for extradural (epidural) hematoma (middle meningeal artery rupture); patient walks/talks then unconscious.
Brain stem death: Irreversible cessation of all brain stem functions. Tests: Absent pupillary reflex, corneal reflex, vestibulo-ocular reflex, gag reflex, cough reflex, spontaneous breathing (apnea test - PCO2 >60 mmHg with no respiratory effort); performed by 2 doctors twice at 6-hour interval; legal basis for organ donation in India.
Gustafson's method: Age estimation from teeth by 6 criteria (scored 0-3 each): Attrition (A), Periodontosis (P), Secondary dentine (S), Cementum apposition (C), Root resorption (R), Root transparency (T) - APSCRT; regression formula gives age estimate.
Parrot's perch position: Victim suspended by wrists tied behind back and elevated; causes brachial plexus stretch injury and respiratory compromise; form of torture (also called "strappado").
Vitriolage: Throwing of acid or corrosive substance on another person with intent to injure/disfigure; IPC Sections 326, 326A, 326B (inserted 2013). Chemical injuries: distinctive pattern (color of acid/alkali injury differs).
Drunkenness vs Concussion:
| Feature | Drunkenness | Concussion |
|---|
| Cause | Alcohol | Head trauma |
| Smell | Alcohol on breath | No alcohol |
| Pupils | Variable, equal | May be unequal |
| Reflexes | Depressed, sluggish | Brisk early; depressed later |
| Memory | Impaired | Retrograde amnesia |
| Convulsions | Rare | May occur |
| Lateralizing signs | Absent | May be present |
| Response to stimulus | May respond | May not respond |
Turner's syndrome (45,XO): Short stature, webbed neck, primary amenorrhea, absent secondary sex characteristics, cubitus valgus, coarctation of aorta; medicolegal: sex determination issues.
Suspended animation: State resembling death with minimal vital functions; causes: cholera, hypothermia, trance, extreme fright, neonatal asphyxia; danger of premature burial; differentiated by: signs of decomposition, lividity, rigor mortis.
Post-mortem caloricity (temperature increase after death): Body temperature rises slightly immediately after death in some cases (fever was present; due to continued bacterial metabolism; tetanus, pontine hemorrhage); rare; duration: 30-60 minutes.
LEGAL/COURT PROCEDURE
Chief examination vs Cross-examination:
- Chief (direct) examination: questions by party calling the witness; conducted first
- Cross examination: questions by opposing party; tests credibility/reliability; leading questions allowed; more rigorous
Infamous conduct (professional misconduct): Conduct disgraceful enough to remove a doctor from practice; examples: adultery with patient, covering for unqualified person, false certification, conviction for serious crime.
In loco parentis: "In place of parent"; person with parental authority but not biological parent; school, orphanage; can give consent for medical treatment of minors.
Borrowed servant doctrine: When an employee is "lent" to another employer; liability shifts to borrowing employer; e.g., hospital anesthesiologist lent to another hospital during procedure.
Conduct money: Money tendered to a witness to cover travel/lodging expenses for attending court; must be paid with subpoena; failure to pay = witness not obligated to attend.
All notes reference: The Essentials of Forensic Medicine & Toxicology, KS Narayan Reddy, 36th Edition (2026); supplemented by Parikh's Textbook of Medical Jurisprudence & Forensic Medicine; PC Dikshit Textbook of Forensic Medicine & Toxicology.
