Autopsy and thanatology

Autopsy and thanatology techniques provide a systematic framework for determining the cause and manner of death through the biological and procedural evaluation of a corpse. Autopsies are categorized into medicolegal investigations, which require state authorization for unnatural deaths, and pathological examinations, which require familial consent to investigate natural disease processes. Specialized autopsy techniques (e.g., virtual autopsy) further refine the diagnostic process in complex cases. The procedural execution of an autopsy follows specific sequences and utilizes standardized incisions and organ removal techniques. Forensic disinterment, or exhumation, and the preservation of specific viscera using specialized preservatives are essential components of the medicolegal investigation in cases of suspected poisoning or human remains. Thanatology tracks the transition from somatic to molecular death, identifying critical markers during the supravital period and the postmortem phase.

Clinical autopsy

• Purposes
  • Medical investigation into the cause of a natural death (i.e., does not consider the manner of death) and any preexisting illnesses
  • Diagnosis of diseases that can only be confirmed postmortem (e.g., Parkinson disease) or if antemortem efforts failed
  • Confirmation that the diagnosis made before death was correct and that the treatments administered were reasonable
  • Requested by next of kin
  • Research
• Authorization
  • In life: patient or health care surrogate
  • Postmortem: next of kin
  • Relatives hand over the body.
• Procedure: usually a partial autopsy

Forensic autopsy

• Purposes
  • Medicolegal investigation into the circumstances of unexplained or possibly unnatural death
  • Establishing the identity of the deceased and the time, place, and manner of death
  • Collecting forensic evidence
  • Reconstructing a crime or accident
• Authorization
  • Does not require authorization from the next of kin
  • Ordered by a court, a coroner, or a medical examiner who deems it necessary or in the public interest; the body is handed over by the investigating officer.
• Procedure: usually a complete autopsy
• Characteristics of death that may require a forensic autopsy
  • Deemed necessary or in the public interest by a coroner or medical examiner
  • Request by the police, district attorney, or a court
  • The circumstances of death are suspicious, unusual, or unnatural, especially homicide and suicide.
  • The cause of death poses a potential threat to public health.
  • Sudden fetus or infant death that appears natural and occurs when in good health
  • Suspected sudden infant death syndrome

Specialized autopsy types

• Psychological autopsy
  • A retrospective assessment of the deceased's mental state prior to death
  • The goal is to understand how the person felt before death, to help determine if the death was suicide, an accident, natural, or homicide.
  • Involves interviewing family members and reviewing medical records
• Virtual autopsy
  • The use of advanced medical imaging (e.g., CT or MRI) before or instead of opening the body
  • Used to document injuries (e.g., fractures, internal bleeding), locate foreign bodies (e.g., bullets), and reconstruct trauma without traditional dissection
  • Example scenarios: religious or cultural concerns, families who do not want an invasive autopsy
  • Advantages: very useful for visualizing foreign bodies, injuries to the skeleton, and the distribution of fluids and/or gas
  • Limitations: not suitable for infections, poisonings, small abnormalities, or microscopic disease

Autopsy technique

Sequence

The order of an autopsy is not always fixed. The order of cavity dissection is modified based on the suspected cause of death to avoid the creation of artifacts or the loss of volatile evidence. Example sequences include:

• Suspected gastrointestinal bleeding: The abdomen is opened first before manipulating the thorax to identify the source and amount of bleeding, before blood can shift within the body.
• Suspected pneumothorax: The thorax is dissected first, because air in the pleural cavity can disappear when the chest is opened later in the autopsy.
• Suspected poisoning: The cranial cavity is opened first, because the characteristic smell of some poisons may still be present and could be masked after opening the abdomen and/or thorax.
• Suspected asphyxial death: The cranial cavity is opened first and the neck is examined last to allow for a relatively bloodless neck dissection and avoid false hemorrhages caused by the autopsy itself (Prinsloo-Gordon artifacts).
• Examination of a newborn: The cranial cavity is opened first, then the abdomen, and finally the thorax to preserve the normal position of the diaphragm, which helps determine if the newborn has breathed after birth.

Types of incisions

Incisions are chosen based on the need for specific exposure and, in some cases, cosmetic considerations.

• I-shaped incision
  • The most common and simplest incision
  • Extends from the chin in the midline down to the pubic symphysis
• Y-shaped incision
  • Primarily used in female individuals for cosmetic purposes
  • Begins at both acromion processes, meets at the xiphoid process, and extends down to the pubic symphysis
• Modified Y-shaped incision
  • Used when a detailed examination of the neck is required (e.g., in cases of strangulation or hanging)
  • Begins behind the ears at the mastoid processes and extends down the sides of the neck to meet at the suprasternal notch
• X-shaped incision
  • Used in custodial deaths; particularly useful for detecting subcutaneous hemorrhages caused by blunt force trauma
  • The incision, usually on the back, runs from both shoulders to the opposite iliac crests, creating an "X" shape.

Organ removal

Removal techniques

The choice of technique depends on the suspected cause of death, the presence of infectious diseases, and the need to study inter-organ relationships.

• Virchow technique
  • Removal and examination of each organ, one at a time
  • Standard approach in most routine autopsies
  • Limitation: disrupts the in situ anatomical relationships between organ systems
• Rokitansky technique
  • Dissection of the organs while still inside the body
  • Used in cases with infection risk (reduces handling and potential exposure) and if anatomical relationships are important (e.g., suspected surgical error)
• Ghon technique: removal of organs in grouped anatomical sections (e.g., neck and chest, abdominal organs, urogenital system), which helps to preserve the organ relationships of each region
• Letulle technique
  • Removal of cervical, thoracic, abdominal, and pelvic organs, at the same time
  • Organs are subsequently dissected outside of the body.
  • Helps understand how organs relate to one another or widespread disease processes

Organ-specific dissection techniques

Organ-specific dissection techniques are used to examine individual organs and organ systems in detail, helping ensure that subtle injuries or pathological changes are not missed.

• Scalp: dissected using a bimastoid incision to expose the skull vault
• Skull vault
  • Adults: usually opened with a Stryker saw
  • Fetus and newborns: opened using scissors
    • Barr technique: the most common method in infants, involving four flaps
    • Beneke technique: A specialized autopsy method used to open the skull in neonates and fetuses
      • Involves making incisions along the cranial sutures to reflect the parietal bones as two lateral flaps, resembling the opening of a book
      • Preserves the integrity of the underlying dural folds, such as the falx cerebri and tentorium cerebelli, to facilitate the identification of birth-related trauma and intracranial hemorrhages
• Brain
  • Examined immediately after removal as a fresh specimen
  • Formalin fixation is preferred because it allows for a detailed neuropathological assessment of fine anatomical structures.
• Spinal cord
  • Examination is uncommon.
  • Reserved for selected cases (e.g., whiplash injury, strychnine poisoning)
  • An anterior approach is possible, although a posterior approach is used more often.
• Heart
  • Dissected using the inflow–outflow method that follows the normal blood flow direction (right atrium → right ventricle → left atrium → left ventricle)
  • Facilitates systematic chamber, valve, and major outflow tract assessment
• Stomach
  • Before the stomach is opened, the cardia and pylorus are double-ligated and divided between the ligatures to preserve gastric contents for chemical or toxicological analysis.
  • Typically opened along the greater curvature
  • The lesser curvature of the stomach is evaluated specifically in cases of acid ingestion, as this area often shows the maximum damage.

Preservation of viscera for chemical analysis

• The preservation of internal organs is essential for toxicological analysis to detect the presence of poisons or drugs.
• In certain legal contexts, a body may be disinterred for forensic investigation through the process of exhumation.
• Standard forensic protocols mandate the collection and preservation of specific biological samples to ensure the accuracy of laboratory results.

Sample types

• Routine samples
  • Blood: typically collected from a peripheral vein because it is considered the most reliable sample for toxicological testing and is mostly unaffected by postmortem redistribution
  • Stomach, small intestine, and the contents of both: collected together in one container, because they may contain ingested substances (e.g., poison, medication) that have not been fully absorbed yet
  • Liver (∼ 500 g) and one-half of each kidney: collected together in a single container, as they are responsible for metabolizing and excreting toxins
• DNA identification samples
  • Blood: preserved with EDTA
  • Teeth: The dental pulp is the preferred source for DNA in decomposed or charred remains.
  • Other: deep muscle tissue and bone (e.g., femur)
• Targeted toxicology samples
  • Brain tissue: alcohol , morphine or other opioids, organophosphates
  • Spleen: cyanide, carbon monoxide
  • Spinal cord (complete): gelsemium, strychnine
  • Heart tissue: digitalis
  • Bone, hair, nails: heavy metals
  • Lung tissue: volatile inhalants
  • Adipose tissue: pesticides

Preservatives

Biological samples must be stored in appropriate preservatives to prevent chemical degradation or bacterial contamination.

• Saturated sodium chloride
  • Common preservative
  • Creates a highly concentrated saline environment, thereby preventing putrefaction
  • Avoided in aconite and most corrosive poisonings
• Rectified spirit
  • Preserves many organic compounds and prevents decomposition
  • Preferred for most organic poisons
  • Avoided in alcohol, phosphorus, chloroform, ether, and phenol poisoning because it can interfere with analysis
• Sodium fluoride
  • Inhibits bacterial growth and glycolysis
  • Used for urine, vitreous humor, and CSF
  • Combined with potassium oxalate for blood samples
• Potassium oxylate
  • Anticoagulant used with sodium fluoride
  • Prevents clotting of blood samples during toxicological testing
• 50% glycerol: stabilizes and preserves viral particles

Exhumation

Exhumation is the lawful digging up of a buried body for forensic examination.

• Authorization: must be authorized by a competent legal authority (e.g., a court, coroner, or magistrate)
• Procedure
  • Identification: The grave and the remains must be definitively identified by family or legal records.
  • Soil samples: Forensic protocols require the collection of soil samples from above, below, and adjacent to the body to differentiate between poisons ingested by the deceased and those that may have entered the body from the surrounding environment (postmortem imbibition), such as arsenic.

Classification of autopsy findings

In cases in which a standard examination does not provide an immediate or definitive cause of death, findings are classified into specific forensic categories.

• Obscure autopsy
  • An autopsy in which the initial gross (visual) findings are insignificant or misleading
  • The cause of death is determined only after additional specialized tests, such as toxicology or histopathology.
• Negative autopsy
  • An autopsy in which no definitive cause of death is found, even after exhaustive macroscopic, microscopic, and toxicological examinations
  • Accounts for approx. 5% of autopsies
• Medical malpractice autopsy: specifically focused on investigating deaths suspected to have resulted from a negligent or substandard medical act

Signs of vitality (vital reactions)

Signs of vitality (not to be confused with vital signs) are signs that an individual was alive at the time of sustaining injury, as opposed to the injury being postmortem.

• Circulation
  • Signs of exsanguination
  • Signs of venous obstruction
  • Embolisms
• Metabolism: metabolism of toxins (metabolites of toxins detectable in urine)
• Respiration
  • Aspiration: soot, blood, water, gastric contents
  • Evidence of toxic gases (e.g., carbon monoxide in the lungs)
  • Subcutaneous emphysema in deep thoracic injuries
  • Collapsed lung in pneumothorax from external application of force
• Central nervous system
  • Soot-free radial bands beside the eyes (crow's feet) in individuals involved in a fire
  • Evidence of a functioning autonomic nervous system at the time of injury: blood that has been swallowed or coughed up

Signs of vitality provide clues that damage to an organism occurred before death.

Identification of poisons

• The identification of a poison during an autopsy is a systematic process involving external and internal examination, collection of specimens (viscera), and chemical analysis.
• In suspected poisoning by volatile substances (e.g., alcohol, cyanide), the skull may be opened early on in the autopsy to detect characteristic odors from brain tissue before they dissipate.

Characteristic odors in poisoning

Some poisons may produce characteristic smells around the mouth, nose, stomach contents, or tissues, but odor is only a supportive finding and should not replace chemical analysis.

• Chloral hydrate , paraldehyde: acrid pear
• Cyanide: bitter almond
• Cannabis: burnt rope
• Ethanol: fruity
• Zinc phosphide: fishy
• Arsenic, phosphorus, aluminium phosphide, organophosphorus compounds: garlic
• Phenol (carbolic acid): medicinal
• Organophosphorus (commercial): kerosene
• Conium maculatum (hemlock): mousy
• Hydrogen sulfide: rotten egg

Characteristic stomach mucosal findings in poisoning

The appearance of the stomach mucosa during autopsy may provide supportive findings in suspected poisoning.

• Arsenic: red, velvety
• Copper sulfate, sodium amytal: blue green
• Phenol (carbolic acid): buff-white, tough, and leathery
• Nitric acid: yellow
• Mercury: slate grey
• Sulfuric acid (oil of vitriol): black, necrotic

Evidence of live birth

The condition of the lungs and the gastrointestinal tract can provide evidence of whether a neonate was alive at birth or stillborn.

• Lung float test: Lungs that are lighter than water suggest that respiration occurred and that the infant was therefore alive at birth; however, the test is unreliable because a variety of factors can lead to false-negative or false-positive results.
  • False-positive : ventilation of lungs from resuscitation attempts or the buildup of gas during putrefaction
  • False-negative : aspiration of liquid or asphyxiation from smothering
• Breslau second life test: Air in the gastrointestinal tract provides clues to how long an infant lived; the further down air is present in the gastrointestinal tract, the higher the probability that an infant was alive at birth.
  • Air in stomach and duodenum: onset of death a few minutes after birth
  • Air in the entire small intestine: onset of death up to 6 hours after birth
  • Air in the entire large intestine: onset of death up to 12 hours after birth

Signs of intrauterine death

Physical examination signs

• Maceration: softening of skin and detachment of the epidermis in a stillborn fetus
  • Represents aseptic autolysis
  • Earliest changes begin around 12–24 hours after death.
  • Features
    • Skin reddening
    • Skin slippage or peeling
    • Hypermobile joints
• Diaphragm level: determined during autopsy
  • Nonrespired lungs: diaphragm lies higher, around the 3rd–4th rib
  • Respired lungs: diaphragm descends and lies around the 6th–7th rib
• Fodéré test: based on lung weight
  • Nonrespired lungs: relatively light
  • Respired lungs: heavier due to factors such as air entry, expansion, and/or increased blood flow
• Ploucquet test: ratio of lung weight to body weight
  • Nonrespired lungs: 1:70
  • Respired lungs: 1:35
• Wreden test: assesses the middle ear cavity
  • Respired newborn: gelatinous embryonic tissue in the middle ear
  • Nonrespired newborn: air in the middle ear

Radiological signs

• Robert sign: A radiographic sign of intrauterine fetal death (IUFD) characterized by gas within the fetal heart, great vessels, and sometimes fetal abdominal vessels.
  • Usually appears after fetal maceration, classically around 12 hours or more after fetal demise, and may be seen on plain abdominal X-ray
  • Often associated with other IUFD signs such as the Spalding sign and fetal spine hyperflexion.
• Ball sign: A radiological sign of intrauterine fetal death characterized by marked hyperflexion, and less commonly hyperextension, of the fetal spine.
  • Results from loss of fetal muscle tone, causing the fetus to appear curled or collapsed on plain abdominal X-ray.
  • Often seen with other late IUFD signs such as Spalding sign and Robert sign.
• Spalding sign: A radiological sign of IUFD characterized by irregular overlapping or overriding of the fetal cranial vault bones.
  • Usually appears after fetal maceration, classically within several days and often within one week of demise.
  • Results from liquefaction of fetal brain tissue and loss of ligamentous structures of the skull.
  • Must be distinguished from physiological skull molding during labor.

Thanatology is the study of death, encompassing the biological, social, and legal aspects of the cessation of life. Taphonomy is the specific study of postmortem resorption and decomposition of the body.

The states of the postmortem period are the supravital period, early postmortem changes, and late postmortem changes (decomposition).

The supravital period is the interval after clinical death during which cells, tissue, and/or organs remain viable. In this period, they still respond to external stimuli before cellular death occurs.

Supravital reactions

• Overview
  • Definition: certain physical functions that persist for some time after the onset of death
  • Represent the interval between clinical death and molecular death
  • Provide specific clues regarding the time of death
  • Clinical significance: critical period for organ retrieval for transplantation (e.g., the cornea must be retrieved within 6 hours)
• Up to 8 hours after onset of death: skeletal musculature
  • Up to 8 hours postmortem: Mechanical stimulation causes slight idiomuscular bulging that may persist for up to 24 hours.
  • 3–5 hours postmortem: Mechanical stimulation causes pronounced reversible idiomuscular bulging.
  • 1.5–2.5 hours postmortem: Zsako muscle phenomenon (i.e., mechanical stimulation causes propagated excitation)
• Up to 17 hours: pupillary response
• Up to 80 hours: motile sperm cells

Early postmortem changes occur within the first 24 hours of death and are the primary markers used to estimate the time since death (TSD).

Eye changes

• Kevorkian sign (cattle trucking): fragmentation of retinal vessels that occurs within minutes to 1 hour postmortem
• Tache noire triangular brown opacities on the sclera due to drying (3–6 hours)

Algor mortis

• Definition: postmortem cooling of the body until it reaches thermal equilibrium with its surroundings
• Results from the cessation of metabolic heat production and subsequent heat loss via conduction, convection, and radiation
• The fall in body core temperature (BCT) follows a sigmoid (inverted S) curve: slow → rapid → slow
• Used to estimate TSD

Postmortem caloricity

• Definition: a condition in which the body remains warm, or the temperature rises, for approximately 2 hours after death
• Results from high metabolic activity just before death or ongoing chemical reactions within the tissues (e.g., bacterial multiplication)
• Common causes
  • Sepsis or severe infection
  • CNS lesions (especially pontine hemorrhage)
  • Hypermetabolic states (e.g., thyroid storm)
  • Poisoning (e.g., cocaine, amphetamines, tetanus, strychnine)
  • Heat stroke
  • Convulsions
• Does not occur in burns

Rigor mortis

• Definition: the stiffening of the muscles after death, potentially with muscle shortening
• Sequence
  • After death, the body initially enters a state of primary flaccidity in which all muscles relax, including sphincters, which may cause the passage of urine and/or feces.
  • 1–2 hours after death, adenosine triphosphate depletion causes permanent binding of actin and myosin, leading to muscle stiffness and the characteristic rigidity of rigor mortis.
  • Rigidity persists for 1–2 days, until proteolysis during decomposition breaks down muscle proteins, which results in relaxation (secondary flaccidity).
  • Follows Nysten rule, progressing from head to toe
  • Develops first in involuntary muscles, especially the myocardium, and then progresses to the voluntary muscles
• Rule of 12
  • 1 hour after death: Rigor mortis begins.
  • Next 12 hours: reaches its peak
  • Following 12 hours: remains in full effect
  • Final 12 hours: disappears
• Cadaveric spasm: sudden stiffening of muscles at the exact moment of death
  • Primary flaccidity is skipped entirely, and muscles become stiff immediately.
  • Usually affects specific voluntary muscles (e.g., a person is found gripping something very tightly)
  • Reflects the state at the moment of death and indicates that the affected person was using the muscles just before death
  • Common situations include homicidal violence , electrocution, suicide gunshot, and drowning

Livor mortis

• Definition: purple-red discoloration of dependent areas of skin not exposed to pressure after circulation stops due to blood settling under the force of gravity (hypostasis)
• Occurrence
  • At least 30 minutes to 2 hours after onset of death ^[1]
  • Maximum observed at 6–12 hours ^[2]
  • Does not occur in cases of severe anemia or shock, or if a body is floating
• Location: Under the force of gravity, blood pools in areas of dependency determined by the position in which the person died. ^[3]
  • Face-up: back of the corpse (i.e., back of the head, chest, abdomen, legs)
  • Hanging death: feet, fingertips, and ear lobes ^[2]
  • Prone position: front of the head, chest, abdomen, legs
  • Standing position: glove and stocking distribution
  • Drowning: face, upper chest, hands, lower arms, feet, and calves ^[4]
  • Livor mortis is evident on the ear lobes and the nail beds.
  • Also occurs in visceral organs (e.g., lungs)
• Features
  • Redistribution: Livor mortis can be altered up to 6 hours after the onset of death; after this period, it becomes permanent (fixation). ^[5]
  • If the body is moved before fixation, new lividity forms (secondary lividity); eventually, livor mortis blends with putrefaction discoloration
  • Blanching
    • Skin turns white when applying pressure within the first ∼ 12 hours. ^[6]
    • In fixation, blanching is absent.
  • Contact pallor
    • Definition: pale areas of skin in dependent body parts that had contact with a surface or are under pressure
    • Pressure compresses blood vessels, which means that blood cannot pool there
    • May help indicate body position after death
• Postmortem staining colors
  • The intensity of color depends on the amount of hemoglobin in the blood. ^[7]
  • The color of livor mortis can be diagnostic for specific poisons or conditions.
    • Bluish-purple: normal livor mortis
    • Greenish-red: hydrogen sulfide (produced in decaying organic matter) ^[6]
    • Dark brown: phosphorus poisoning
    • Brownish-red: poisoning with methemoglobin-forming substances (such as nitrite or aniline)
    • Pale pink (barely pronounced): blood loss, severe anemia, severe hemorrhage
    • Cherry red: carbon monoxide poisoning
    • Bright red: cyanide poisoning ^[6]
    • Black: opium

Livor mortis occurs approx. 30 minutes to 2 hours after the onset of death and is the first definite sign of death.

Other

• Injuries incompatible with life (e.g., incineration, decapitation)
• Postmortem clots: separation of red blood cells and plasma creates clots of plasma that resemble chicken fat and blackish-red erythrocyte clots that have a currant jelly appearance.

Decomposition

Decomposition is the breakdown of bone and tissue through aerobic and anaerobic processes. Factors that influence decomposition include:

• Insect and other animal activity
  • Can further advance decomposition
  • Entomological investigations of larval development can help determine the time of death.
• Environment: decomposition is accelerated by warmth and moisture.
• Casper's rule: a body will show similar marks of decomposition after 1 week of exposure to air, 2 weeks submerged under water, and 8 weeks of interment.

Autolysis

• Overview
  • Definition: digestion of cells by their own enzymes
  • Begins minutes to hours after death
  • Overlaps with putrefaction
• Process
  • Loss of oxygen disrupts cellular metabolism, and enzyme-filled lysosomes rupture.
  • Enzymes start digesting proteins, cell membranes, and organelles.
• Effects
  • Blister formation, skin separation
  • Tissue softening

Putrefaction

• Overview
  • Definition: the process of decomposition after death driven by bacteria, especially from the gut, that spread through tissues and break down proteins and other cellular components, producing pigments, fluids, and gases that result in the typical signs of decomposition
  • Certain substances (e.g., strychnine, heavy metals, and carbolic acid) can delay the onset.
• Color changes
  • Onset within 12–48 hours of death; varies with environmental temperature
  • First external sign: greenish discoloration of the skin over the right iliac fossa
  • Venous patterning (marbling): begins 24–48 hours after death and resembles a network of veins or a marble pattern that is green, purple, or blackish
    • Caused by bacteria that produce hydrogen sulfide, which reacts with hemoglobin from lysed erythrocytes and forms sulfhemoglobin (greenish pigment)
    • At the same time, blood vessels are broken down, and the pigment spreads along the vessels, which creates the branched pattern.
• Gas formation
  • Typically occurs several days after death, but can be accelerated by warmer temperatures
  • After death, oxygen is depleted, which creates an anaerobic environment.
  • Gut bacteria spread through the body and produce gases (methane, carbon dioxide, hydrogen, ammonia, and hydrogen sulfide) as they consume the body's carbohydrates, proteins, and lipids.
  • Results in distension over several areas of the body (e.g., abdomen, scrotum), blisters and bullae, and, potentially, shifting of limbs due to gas buildup
  • Postmortem purge: The pressure from these gases can force reddish-brown fluid out of the mouth and nose.
• Tissue liquefaction: Solid tissues lose their form and turn into a soft, semi-liquid, or liquid mass due to autolysis and putrefaction.
  • The larynx and trachea are affected first, followed by:
    • Stomach and intestine
    • Spleen
    • Liver
    • Brain
    • Heart
  • Late: skin, prostate, nongravid uterus
  • Last: bone and teeth

Other forms of decomposition

• Mummification: Warm environments with extremely low humidity can cause bodies to mummify and resist decomposition.
• Adipocere formation: Wet anaerobic environments (e.g., moors, bodies of water) may induce bacterial hydrolysis of fatty tissue (saponification), transforming tissue into a waxy substance called adipocere.
• Degloving: Thermal exposure, immersion, or advanced decomposition of skin and tissues result in degloving of skin (common in hands and feet).

Other findings

• Vibices: pale marks caused by pressure (e.g., from a rope in hanging death or generally, from tight clothing such as socks, belt, or bra)
• Tardieu spots: dark pinpoint spots that develop in dependent areas (e.g., in the legs of a hanged person due to increased gravitational pressure)