Forensic Medicine & Toxicology
High-yield MBBS Forensic Medicine & Toxicology question bank — medical jurisprudence, identification, thanatology, injuries, asphyxia, forensic sexology and toxicology, at Reddy’s / Parikh depth.
12chapters144questions77High-Yield
Definition
An autopsy (necropsy, postmortem examination) is the systematic examination of a dead body; the medicolegal autopsy is conducted on the order of a legal authority.
Types & Objectives
- Clinical (pathological) autopsy — with relatives’ consent, to confirm diagnosis and study disease
- Medicolegal (forensic) autopsy — on the order of police or magistrate; consent of relatives is not required
- Objectives: establish identity, cause of death, manner of death, time since death
- To determine whether death was natural or unnatural, and to collect trace evidence
- In infants — determine live birth, viability and age
Rules of Medicolegal Autopsy
- Conducted only by a registered medical practitioner on written authorisation
- Done in daylight wherever possible (colour changes are misjudged in artificial light)
- Complete autopsy — all three cavities (cranial, thoracic, abdominal) must be opened, however obvious the cause
- Never delegate; notes taken during the examination, not afterwards
- Identity confirmed by the escorting constable; body labelled
- Report written in non-technical language, opinion given at the end
The autopsy answers who, how, when and by what means. Feature Clinical Medicolegal Authorised by Relatives Police/Magistrate Consent Required Not required Extent May be partial Always complete Applied
- There is no time limit — autopsy may be done at any hour, but daylight is preferred
- Preserve viscera whenever poisoning cannot be excluded
🔑KEY POINTS TO REMEMBER- Medicolegal autopsy needs legal authorisation, not relatives’ consent.
- Objectives: identity, cause, manner and time of death.
- Must be complete — all three cavities opened, done preferably in daylight.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
The autopsy procedure is a systematic sequence of external and internal examination performed in a fixed order.
External Examination
- Clothing — examined, described, preserved for trace evidence; note tears and stains matching wounds
- Identification data — sex, age, height, weight, build, scars, tattoos, deformities
- Postmortem changes — cooling, lividity, rigor mortis, decomposition
- Injuries — site, size, shape, direction, age; measured from fixed landmarks; photographed
- Natural orifices, hands (defence wounds, foreign material under nails), genitalia
Internal Examination
- Cranial cavity: coronal (intermastoid) scalp incision; skull cap removed, brain examined
- Thorax and abdomen opened by I-shaped, Y-shaped or modified Y incision
- Rokitansky (in situ), Virchow (organ by organ), Ghon (en bloc) and Letulle (en masse) techniques
- Each organ weighed, sectioned and described; neck dissected last and bloodlessly in suspected strangulation
- Spinal cord opened when indicated; samples for histopathology and toxicology
- Body reconstituted and handed over
External findings guide where internal examination must be most careful. Technique Method Virchow Organ by organ Ghon En bloc Letulle En masse Applied
- Bloodless neck dissection avoids artefactual haemorrhage
- Photograph all injuries with a scale before dissection
🔑KEY POINTS TO REMEMBER- External examination covers clothing, identity, postmortem changes and injuries.
- Internal examination opens cranial, thoracic and abdominal cavities.
- Virchow, Ghon, Rokitansky and Letulle are the standard evisceration techniques.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Exhumation is the lawful digging out of a buried body from the grave for medicolegal examination.
Indications & Legal Requirements
- Suspected criminal poisoning or homicide discovered after burial
- Establishing identity for insurance or inheritance disputes
- Fresh evidence emerging after burial; accidental death and compensation claims
- Faulty or incomplete earlier autopsy
- Ordered in writing by a Magistrate (in India, no time limit); in England limited to a fixed period in some situations
- Conducted in the presence of the Magistrate, police officer and doctor
Procedure
- Performed in early morning daylight, in the presence of the authorities
- Identity of the grave established by the caretaker, register and relatives
- Grave screened from public view; coffin identified from its plate
- Samples of earth taken from above, below and the sides of the coffin, and a control from a distance (to exclude soil contamination by arsenic and other substances)
- Full autopsy performed; viscera, hair, nails and bones preserved for chemical analysis
- Body reburied after examination; complete records and photographs maintained
Soil control samples exclude contamination from the burial ground. Requirement Detail Order Magistrate, written Time limit (India) None Time of day Early morning Applied
- Arsenic and antimony delay putrefaction — bodies may be well preserved
- Hair and nails are valuable for detecting chronic heavy-metal poisoning
🔑KEY POINTS TO REMEMBER- Exhumation requires a written Magistrate’s order; no time limit in India.
- Done in early morning daylight before the Magistrate and police.
- Soil samples from around and away from the coffin exclude contamination.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Preservation of viscera is the collection and dispatch of tissues and fluids to the forensic science laboratory for chemical analysis in suspected poisoning.
Samples & Preservatives
- Bottle 1 — stomach with contents and upper 30 cm of small intestine
- Bottle 2 — liver (500 g), half of each kidney, spleen
- Bottle 3 — blood (10 mL) preserved in sodium fluoride and potassium oxalate
- Bottle 4 — urine (100 mL)
- General preservative: saturated saline; alternative rectified spirit
- Preservative should be about one-third the volume and cover the viscera
Special Points & Dispatch
- Rectified spirit must NOT be used when alcohol, phosphorus, acetic acid, paraldehyde or ether is suspected — use saturated saline
- Saturated saline must NOT be used for suspected corrosive acids
- A control sample of the preservative is always sent separately
- Bottles cleaned, wide-mouthed, sealed with the doctor’s and Magistrate’s seals
- Sent through police with a forwarding letter, inquest copy and sample seal impression
- In suspected heavy-metal poisoning also preserve hair, nails, bone and skin
The control sample proves the preservative itself was not contaminated. Bottle Contents 1 Stomach + intestine 2 Liver, kidney, spleen 3 Blood (NaF + oxalate) 4 Urine Applied
- Sodium fluoride prevents postmortem alcohol formation and glucose breakdown
- Maintain the chain of custody — essential for court admissibility
🔑KEY POINTS TO REMEMBER- Four bottles: stomach with intestine; liver, kidney, spleen; blood; urine.
- Saturated saline is the usual preservative; rectified spirit is avoided for alcohol.
- Always send a control sample of preservative and maintain chain of custody.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Medicolegal examination of the living is the examination of a person on the request of an investigating authority to document injuries, age, intoxication or fitness.
General Rules
- Conducted on written requisition from police or court
- Consent must be obtained; a person cannot be examined forcibly (except an accused under Section 53 CrPC, where reasonable force is permitted)
- Identity confirmed by the escorting constable; a female must be examined in the presence of a female attendant
- Detailed history, then systematic examination; all findings recorded contemporaneously
- Injuries described by site, size, shape, direction, type and age, measured from fixed landmarks
Common Situations
- Injury (wound) certificate — nature of injury: simple, grievous or dangerous
- Age estimation — by teeth and radiological ossification
- Sexual offences — victim and accused; samples for the sexual assault kit
- Drunkenness — clinical examination plus blood alcohol estimation
- Insanity, impotence, sterility, pregnancy, delivery; fitness for detention or trial
- Report handed only to the requisitioning authority
Consent and identification must precede every medicolegal examination. Situation Key output Assault Injury certificate Age dispute Radiological opinion Drunkenness Blood alcohol Applied
- Never hand the report to the patient or relatives
- Give a final opinion only after all reports are available
🔑KEY POINTS TO REMEMBER- Examination requires written requisition, consent and proper identification.
- Section 53 CrPC permits examination of an accused using reasonable force.
- Injuries described by site, size, shape, direction and age; report goes to the authority.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
An obscure autopsy is one in which the findings are minimal, non-specific or absent, and do not adequately explain the death.
Causes
- Inadequate history and lack of scene information
- Incomplete or careless autopsy — cavities not opened, neck not dissected
- Deaths from vagal inhibition, epilepsy, anaphylaxis, arrhythmia
- Concealed trauma — internal injury without external marks (child abuse, blunt abdominal injury)
- Poisoning not detected by routine analysis
- Biochemical deaths — hypoglycaemia, diabetic ketoacidosis, electrolyte disturbance
Approach
- Obtain full history, hospital records and scene details
- Repeat a meticulous and complete dissection
- Send tissue for histopathology; preserve viscera for toxicology
- Vitreous humour for glucose, urea and electrolytes
- Microbiology and, in young sudden deaths, genetic (molecular) autopsy
- If still unexplained, report honestly as undetermined — never speculate
Ancillary investigations convert many obscure autopsies into explained deaths. Investigation Detects Histopathology Myocarditis, infarct Toxicology Poisons Vitreous Diabetes, electrolytes Applied
- Differs from negative autopsy, where nothing at all is found
- Never write a speculative cause merely to complete the form
🔑KEY POINTS TO REMEMBER- Obscure autopsy shows minimal or non-specific findings.
- Causes: poor history, incomplete autopsy, vagal inhibition, poisoning.
- Managed by histopathology, toxicology and vitreous biochemistry.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Autopsy artefacts are changes produced after death or during handling that may be mistaken for antemortem findings.
Types
- Postmortem changes — lividity mistaken for bruising; skin slippage for scalding; putrefactive gas bloating for pregnancy
- Resuscitation artefacts — rib and sternal fractures, defibrillator burns, needle marks, gastric contents in airway
- Handling and transport — abrasions from dragging, fractures from rough transport
- Animal and insect activity — rodent or fish bites resembling wounds
- Heat artefacts — pugilistic attitude, heat fractures, heat haematoma mimicking extradural haematoma
- Dissection artefacts — air embolism, artefactual neck haemorrhage
Avoidance & Importance
- May lead to a wrong opinion on cause and manner of death and miscarriage of justice
- Careful, gentle handling and bloodless neck dissection
- Note all resuscitation and treatment given before death
- Correlate every finding with the history and scene
- Vital reaction (haemorrhage into tissues, inflammation) distinguishes antemortem injury
Vital reaction is the key to separating true injury from artefact. Artefact Mimics Lividity Bruise Heat haematoma Extradural haematoma Rat bite Incised wound Applied
- Always ask what resuscitation was performed
- Incise suspected bruises — lividity shows no tissue infiltration
🔑KEY POINTS TO REMEMBER- Artefacts are postmortem changes mistaken for antemortem findings.
- Include lividity as bruise, resuscitation fractures, heat haematoma, animal bites.
- Vital reaction distinguishes genuine antemortem injury.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
A second autopsy is a repeat postmortem examination carried out after the first, usually on the order of a court or higher authority.
Indications
- Dissatisfaction of relatives with the first autopsy report
- Allegation of a defective or biased first examination
- New evidence coming to light after the first autopsy
- Court or higher authority requiring an independent opinion
- Body exhumed for re-examination
- Disputed cause of death in custodial or high-profile cases
Limitations & Conduct
- Ordered only by a Magistrate or court
- Ideally performed by a board of doctors senior to the first examiner
- Organs already dissected and removed — findings inevitably limited
- Decomposition, embalming and burial changes further obscure findings
- Artefacts of the first autopsy may be misread
- First autopsy report, photographs and preserved samples must be available
The value of a second autopsy depends on how well the first preserved evidence. Aspect Detail Ordered by Magistrate/court Performed by Board of doctors Value Limited Applied
- Good photography and record-keeping at the first autopsy are essential
- Preserved tissue blocks may still yield decisive information
🔑KEY POINTS TO REMEMBER- Second autopsy is ordered by a Magistrate or court, usually after dispute.
- Best conducted by a board of senior doctors.
- Value is limited since organs are already dissected — first-autopsy records are crucial.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Embalming is the chemical preservation of a dead body to delay decomposition, disinfect it and restore a natural appearance.
Technique & Fluids
- Arterial embalming — fluid injected into the carotid or femoral artery while blood drains from the corresponding vein
- Cavity embalming — trocar used to aspirate and inject the body cavities
- Chief agent: formaldehyde (formalin) — fixes tissue proteins
- Other constituents: methanol, glycerine, sodium borate, sodium citrate (anticoagulant), eosin for colour, and perfume
- About 5–10 litres of fluid used
Medicolegal Importance
- Autopsy must be completed and viscera preserved BEFORE embalming
- Formaldehyde destroys or alters many poisons — alkaloids, alcohol; makes chemical analysis unreliable
- Fixes tissues, hardening organs and changing the appearance of injuries
- Makes DNA analysis and blood grouping difficult
- Legally required for transport of a body abroad or over long distances
- Embalming without permission in a medicolegal case is an offence (destruction of evidence)
Embalming before autopsy destroys evidence irretrievably. Agent Function Formaldehyde Fixation Sodium citrate Anticoagulant Eosin Natural colour Applied
- Always ask whether a body has been embalmed before autopsy
- Note embalming in the report — it limits toxicological conclusions
🔑KEY POINTS TO REMEMBER- Embalming preserves the body using formaldehyde by arterial and cavity injection.
- Autopsy and viscera preservation must precede embalming.
- Formalin destroys many poisons and hampers DNA analysis.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Examination of skeletal or mutilated remains aims to establish identity and, where possible, the cause and manner of death from fragmentary material.
Sequence of Questions
- Are the remains bone? — distinguish from wood, plastic, stone
- Human or animal? — by morphology, histology (Haversian systems) and precipitin test
- How many individuals? — count duplicated bones
- Sex — pelvis (most reliable), then skull
- Age — epiphyseal fusion, teeth, skull sutures, pubic symphysis
- Stature — regression formulae from long bones (femur best)
- Race — skull shape, nasal index, cephalic index
Further Examination
- Time since death — presence of soft tissue, periosteum, odour, ultraviolet fluorescence, Benzidine test for blood
- Cause of death — fractures, cut marks, bullet holes, healed injuries
- Individual identification — old fractures, implants, dental records, DNA (from teeth and long bones)
- Superimposition and facial reconstruction
- Radiographs of all remains; complete photographic documentation
Identification proceeds from the general to the individual. Question Best method Sex Pelvis Stature Femur Identity DNA, dental Applied
- Teeth and femur give the best DNA yield in old remains
- Recover the entire scene systematically with an archaeologist if possible
🔑KEY POINTS TO REMEMBER- Establish first whether remains are human, then number of individuals.
- Pelvis for sex, epiphyses and teeth for age, femur for stature.
- DNA from teeth and long bones gives individual identification.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Virtual autopsy (virtopsy) is non-invasive postmortem examination using imaging techniques such as CT and MRI instead of, or before, conventional dissection.
Techniques & Advantages
- Postmortem CT — excellent for fractures, foreign bodies, bullets, gas collections
- Postmortem MRI — better for soft tissue, brain and cardiac lesions
- Postmortem angiography; 3D surface scanning; image-guided biopsy
- Non-invasive — acceptable where religious or cultural objection to dissection exists
- Data are permanently stored and can be reviewed or re-examined by others later
- Objective, reproducible; safer where infection risk is high
Limitations
- Expensive equipment and requires trained radiologists
- Cannot assess colour, odour, texture or subtle findings
- Poor at detecting early myocardial infarction, pulmonary embolism and vascular occlusions
- No tissue for histopathology or toxicology unless biopsy added
- Not yet legally accepted as a full replacement for conventional autopsy in India
- Best used as a complement to, not a substitute for, classical autopsy
Imaging supplements dissection rather than replacing it. Modality Best for CT Fractures, bullets MRI Soft tissue, brain Angiography Vessels Applied
- Especially valuable in mass disasters and firearm deaths
- Useful where relatives object to dissection on religious grounds
🔑KEY POINTS TO REMEMBER- Virtopsy uses postmortem CT and MRI for non-invasive examination.
- CT is best for fractures and bullets; MRI for soft tissue and brain.
- Cannot replace conventional autopsy — no histology or toxicology.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Authorisation for autopsy is the legal permission required before a postmortem examination may be conducted.
Medicolegal Autopsy
- Authorised by a police officer not below the rank of Sub-Inspector, or by a Magistrate
- Consent of relatives is NOT required
- Requisition must be in writing, with the inquest report (panchanama) and a copy of the police report
- Body must be identified by the escorting police constable
- Doctor should not begin without written authorisation
- Conducted by a registered medical practitioner — usually a government doctor
Clinical (Pathological) Autopsy
- Requires written consent of the legal next of kin
- Purpose is to confirm the diagnosis, assess treatment and for teaching or research
- Relatives may limit the extent of the examination
- Cannot be performed in any medicolegal or suspicious case — must be referred to the police
- Anatomy Act governs the use of unclaimed bodies for dissection and teaching
- Consent also needed under the Transplantation of Human Organs Act for organ retrieval
The nature of the death determines who must authorise the examination. Type Authorised by Consent Medicolegal Police/Magistrate Not needed Clinical Next of kin Essential Applied
- If a clinical autopsy reveals unnatural death, stop and inform the police
- Retain the written authorisation with the autopsy record
🔑KEY POINTS TO REMEMBER- Medicolegal autopsy is authorised in writing by police (Sub-Inspector or above) or Magistrate.
- Relatives’ consent is not required for a medicolegal autopsy.
- Clinical autopsy needs written consent of the next of kin.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.