MBBS Forensic Medicine Syllabus

What is meant by the medico-legal concept of "death"? State the medical definition used (brain-stem death).

Death is the irreversible cessation of integrated functioning of the organism. Modern legal/medical definition is brain-stem death: irreversible loss of brain-stem function (apnoea, loss of brain-stem reflexes), even if circulation is maintained artificially. (Somatic death = stoppage of heart, respiration, and brain.)

Differentiate somatic (clinical) death from molecular (cellular) death.

Somatic death is the stoppage of vital functions of the body as a whole (heartbeat, respiration, brain activity). Molecular death is the death of individual cells/tissues, occurring 1–2 hours after somatic death.

List the three primary modes of death (Bichat's classification).

Coma (failure of the brain/nervous system), Syncope (failure of the heart/circulation), and Asphyxia (failure of respiration/oxygenation). Death ultimately results through one or a combination of these.

Differentiate "cause," "mechanism," and "manner" of death.

Cause: the disease/injury initiating the lethal sequence (e.g., gunshot wound). Mechanism: the physiological derangement producing death (e.g., haemorrhage/exsanguination). Manner: how the death arose — natural, accidental, suicidal, homicidal, or undetermined.

List the early (immediate) signs of death.

Insensibility and loss of voluntary movement; cessation of respiration; cessation of circulation/heartbeat; loss of corneal and pupillary reflexes; and pallor with loss of skin elasticity.

What is algor mortis and approximately how fast does body temperature fall after death in temperate conditions?

Algor mortis is post-mortem cooling of the body. After an initial plateau, temperature falls roughly $1.5\,^{\circ}\mathrm{F}$ per hour (about $0.8\text{–}1\,^{\circ}\mathrm{C/h}$) until it reaches ambient temperature, useful for estimating time since death.

State the simple rule-of-thumb formula for estimating time since death from rectal temperature (Fahrenheit).

$$\text{Time since death (hours)} \approx \frac{98.4 - \text{Rectal temperature }(^{\circ}\mathrm{F})}{1.5}$$ This assumes a normal antemortem temperature and a fall of about $1.5\,^{\circ}\mathrm{F}$ per hour.

Define rigor mortis and give its typical time course.

Rigor mortis is post-mortem stiffening of muscles due to depletion of ATP and formation of stable actin-myosin bonds. It begins 1–2 h after death, is complete in about 12 h, persists ~12 h, and passes off in about 12 h (the "12-12-12" rule in temperate climates).

What is cadaveric spasm and how does it differ from rigor mortis?

Cadaveric spasm (instantaneous rigor) is the immediate, instantaneous stiffening of a group of voluntary muscles at the moment of death, with no preceding primary flaccidity. Unlike rigor mortis, it cannot be artificially produced and has great medico-legal value (e.g., a weapon firmly grasped suggests suicide).

Define livor mortis (post-mortem lividity/hypostasis) and state when it becomes fixed.

Livor mortis is the bluish-purple discolouration from gravitational settling of blood in dependent vessels after circulation stops. It starts ~30 min–2 h, is well developed by 4 h, and becomes fixed (does not shift on repositioning) at about 6–8 h.

What colour of post-mortem lividity suggests carbon monoxide and cyanide poisoning respectively?

Cherry-red lividity suggests carbon monoxide (carboxyhaemoglobin) poisoning; bright red/pink also occurs in cyanide poisoning and cold exposure. Brown (chocolate) lividity suggests methaemoglobin-forming poisons (e.g., nitrites, potassium chlorate).

What is decomposition, and what are its two main processes?

Decomposition (putrefaction) is the late post-mortem destruction of soft tissues by autolysis (self-digestion by intrinsic enzymes) and putrefaction (bacterial breakdown), producing colour changes, gases, and liquefaction.

What is the earliest external sign of putrefaction and when does it appear?

Greenish discolouration of the skin over the right iliac fossa (over the caecum), appearing about 12–24 hours after death in temperate climates, due to sulphmethaemoglobin formation.

Define adipocere and the conditions favouring its formation.

Adipocere (saponification) is a greasy, waxy substance formed by hydrolysis and hydrogenation of body fat into fatty acids. It favours warm, moist, anaerobic environments and begins after about 3 weeks–months, indicating prolonged death.

Define mummification and its favouring conditions.

Mummification is the dehydration and desiccation of tissues that become dry, leathery, and shrunken. It requires a dry, warm environment with good air circulation (e.g., hot dry climate) and takes several weeks to months.

How are entomological (insect) findings used to estimate time since death?

The predictable succession of insect colonization (e.g., blowflies laying eggs within hours, with larval/pupal development stages) allows estimation of the minimum post-mortem interval based on the oldest insect stage present and ambient temperature.

Define a forensic (medico-legal) autopsy and how it differs from a clinical/pathological autopsy.

A forensic autopsy is performed on legal authority (police/magistrate) to determine cause, manner, and time of death and to recover evidence in suspicious, unnatural, or unexplained deaths. A clinical autopsy is done with relatives' consent to study disease and confirm diagnosis. Forensic autopsy does not require relatives' consent.

List the key objectives of a medico-legal autopsy.

To establish the identity of the deceased; determine the cause of death; determine the time since death; determine the manner of death (homicide/suicide/accident/natural); collect and preserve trace and biological evidence; and, in the newborn, determine live birth and viability.

Name the three standard incisions used to open the body at autopsy.

The I-shaped (straight) incision, the Y-shaped incision, and the modified Y (V over chest to symphysis pubis) incision — all extending from the chest/neck to the pubic symphysis to expose thoracic and abdominal cavities.

What samples are routinely preserved at autopsy in a suspected poisoning case, and the preservative used?

Stomach with contents, portions of liver, kidney, and intestine, and blood/urine are preserved. The routine chemical preservative is saturated saline; for blood (especially alcohol) use sodium fluoride with potassium oxalate. Use rectified spirit only when alcohol/CO is NOT suspected.

State the four phases of disaster victim identification (DVI) per Interpol.

Phase 1: Scene (recovery and documentation of remains). Phase 2: Post-mortem (examination of remains). Phase 3: Ante-mortem (collecting data on the missing). Phase 4: Reconciliation (matching PM and AM data); followed by debriefing.

List the primary (scientifically reliable) methods of identifying human remains in mass disasters.

The three primary identifiers are fingerprints (dactylography), dental records (forensic odontology), and DNA profiling. These are considered conclusive; secondary methods (clothing, personal effects, visual ID, scars, tattoos) only support identification.

How is the sex of skeletal remains best determined?

The pelvis is the most reliable bone (female: broad, shallow, with a wide subpubic angle $>90^{\circ}$, oval inlet; male: narrow, deep, subpubic angle $<90^{\circ}$, heart-shaped inlet). The skull is the second most reliable. Sex determination accuracy is ~95% with the pelvis alone.

Define an injury (wound) and give the basic classification by causative force.

A wound is any disruption of the natural continuity of body tissues. Classified as: mechanical (blunt force, sharp force, firearm), thermal (heat/cold), chemical, and electrical injuries; mechanical blunt-force wounds include abrasions, contusions, and lacerations.

Differentiate an abrasion, a contusion (bruise), and a laceration.

Abrasion: superficial removal of epidermis by friction. Contusion: extravasation of blood into tissues from ruptured vessels, skin intact. Laceration: a tear/split of skin and tissues from blunt force, with ragged margins, tissue bridges, and abraded/contused edges.

Differentiate an incised wound from a laceration.

Incised wound (sharp force): clean, well-defined regular margins, no tissue bridges, length > depth, spindle-shaped. Laceration (blunt force): irregular ragged margins, tissue bridges across the wound, surrounding abrasion/contusion, hair bulbs intact.

Differentiate a stab wound from an incised wound and what a stab wound indicates about the weapon.

In a stab (punctured) wound the depth is greater than the surface length, whereas in an incised wound length exceeds depth. The wound's dimensions can indicate the width and at least minimum length of the blade and the direction of thrust.

What are patterned injuries and give two examples.

Patterned injuries reproduce the shape of the object causing them, aiding weapon identification. Examples: tramline (railway-track) contusions from a cylindrical rod (two parallel lines with a pale centre); and imprint/bite marks, tyre marks, or buckle/whip marks reflecting the offending object.

Distinguish antemortem from postmortem wounds.

Antemortem wounds show vital reactions: external/internal haemorrhage, retraction/gaping of edges, signs of inflammation and healing, and enzyme/histamine changes. Postmortem wounds show little or no bleeding, no retraction, no vital inflammatory reaction, and yellow gaping edges.

In wound ballistics, differentiate the entry and exit wounds of a gunshot.

Entry wound: usually smaller, round/oval, inverted margins, with an abrasion collar and grease/dirt ring; may show soot/tattooing if close. Exit wound: usually larger, irregular/stellate, everted margins, no abrasion collar, and no soot/tattooing.

Describe the features distinguishing contact, close, and distant range gunshot entry wounds.

Contact: muzzle imprint, blackened/seared margins, cherry-red wound from CO, cruciate tearing (over bone). Close range (within scorching/tattooing distance): singeing, soot/blackening (within ~30 cm), and tattooing/stippling from unburnt powder (up to ~60–90 cm). Distant: only the abrasion collar, no soot or tattooing.

What is tattooing (stippling) and why is it medico-legally important?

Tattooing is the punctate abrasions from unburnt/partially burnt gunpowder grains striking the skin around an entry wound. It cannot be wiped away (unlike soot), indicates a close range of fire (up to ~60–90 cm), and helps determine firing distance and rule out a postmortem/distant shot.

Define rape (sexual intercourse without consent) and the medico-legal proof required for the offence.

Rape is unlawful sexual intercourse with a person without valid consent (or with a minor below the age of consent, even if she consents). Legally, the slightest penetration of the vulva by the penis is sufficient to constitute the offence; rupture of the hymen or emission of semen is not necessary.

List the key components of the clinical examination of a sexual assault victim.

Informed consent; detailed history; general examination for injuries/struggle marks and mental state; local genital examination (hymen, vulva, vagina, signs of penetration/injury); collection of evidence (vaginal/oral/anal swabs, pubic hair, clothing, stains, nail clippings); and documentation with chain of custody.

What forensic samples are collected from a sexual assault victim and what are they tested for?

Vaginal/cervical, oral, and anal swabs and smears (for spermatozoa, semen, and DNA); matted/combed pubic hair; nail clippings/scrapings; blood and urine (for alcohol/drugs/DNA); and stained clothing — tested for semen (acid phosphatase, PSA/p30), spermatozoa, and DNA profiling.

What is the significance of acid phosphatase and PSA (p30) in seminal stain examination?

Acid phosphatase is a presumptive screening test for semen (high levels in seminal fluid). Prostate-specific antigen (PSA/p30) is a more specific confirmatory marker of seminal fluid, positive even in azoospermic or vasectomized men where spermatozoa are absent.

List the medico-legal signs used to diagnose pregnancy and their relevance.

Positive signs include fetal heart sounds, fetal movements felt by the examiner, fetal parts on palpation, and ultrasound/X-ray visualization of the fetus. Medico-legally relevant in cases of concealed birth, criminal abortion, claims of inheritance, divorce/nullity, and to defer sentence on a pregnant woman.

List the signs of recent delivery in a living woman.

Breasts enlarged with colostrum/milk and prominent veins; lax abdominal wall with striae gravidarum; involuting uterus palpable above pubis; lochia discharge; a soft, patulous cervix with lacerations; and a torn/healing perineum. These help establish recent childbirth in medico-legal cases.

State the medico-legal criteria for determining whether a newborn was live-born (separate existence).

Evidence of separate existence after complete birth: respiration established (lungs voluminous, pink, float on water — hydrostatic test positive; air in stomach/intestines), changes in the circulatory system (closure/changes of ductus and umbilical vessels), and presence of vital reactions, distinguishing live birth from stillbirth.

Describe the hydrostatic (lung flotation) test and its limitations.

The lungs (and pieces) are placed in water; if respiration occurred they contain air and float, indicating live birth. Limitations: false positives from putrefactive gases or artificial respiration, and false negatives from atelectasis, pneumonia, or after expelling air — so it must be interpreted with other evidence.