Autopsy and thanatology

The study of autopsy and thanatology techniques provides a systematic framework for determining the cause and manner of death through the biological and procedural evaluation of a deceased body. 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 buried 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 pre-existing illnesses
  • Diagnosis of diseases that can only be confirmed postmortem (e.g., Parkinson's disease) or where 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 healthcare 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 deaths
  • Establishing the identity of the decedent and the time, place, and manner of death
  • Collect forensic evidence
  • Reconstruct 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; body is handed over by 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/medical examiner
  • Request by the police, by the district attorney, or a court
  • If circumstances of death are suspicious, unusual, unnatural, esp. homicide and suicide
  • If cause of death poses a potential threat to public health
  • Sudden fetus/infant deaths that appear natural and occur when in good health
  • Suspected sudden infant death syndrome (SIDS)

Specialized autopsy types

• Psychological autopsy
  • A retrospective assessment of the deceased's mental state prior to death
  • Goal is to understand how the person felt before death to help determine if death was suicide, an accident, natural, or even a 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 for a virtopsy include religious or cultural concerns or families that do not wish an invasive autopsy
  • Advantages: great for visualizing foreign bodies, injuries to the skeleton, and distribution of fluids and/or gas
  • Limitations: not feasible for infections, poisonings, small abnormalities, 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. Examples 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: cranial cavity is opened first, because characteristic smell of some poisons may still be present and could be masked after opening the abdomen and/or thorax
• Suspected asphyxial death: cranial cavity is opened first, neck is examined last to allow for a relatively bloodless neck dissection, and avoidance of false hemorrhages caused by autopsy itself (Prinsloo-Gordon artifacts)
• Examination of a newborn: head → abdomen → 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 females for cosmetic purposes
  • Incision 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 to detect subcutaneous hemorrhages caused by blunt force trauma
  • Incision, usually on the back, runs from both shoulders to the oppsite 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 individually, 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 they still remain inside the body
  • Used in cases with infection risk (because it reduces handling and potential exposure) and when anatomic 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 together as one
  • Organs are subsequently dissected outside 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: calvarium is usually opened with a Stryker saw
  • Fetus/newborns: opened using scissors
    • Barr technique: the most common method in infants, involving 4 flaps
    • Beneke technique: involves 2 flaps
• Brain
  • Examined immediately after removal as a fresh specimen
  • Formalin fixation is preferred because it allows for a more detailed neuropathological assessment of fine anatomical structures
• Spinal cord
  • Examination is uncommon
  • Reserved for select cases (e.g., whiplash injury, strychnine poisoning)
  • Anterior approach is possible, although the 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 stomach is opened, 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
  • Magenstrasse (lesser curvature) 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, its contents, and the small intestine with its contents: collected together in one container, because they may contain ingested substances (e.g., poison, medication) that have not been fully absorbed yet
  • Liver (approx. 500 g) and one-half of each kidney: collected in another 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/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.

Exhumation

Exhumation is the lawful digging out 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. This is necessary 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 where a standard examination does not provide an immediate or definitive cause of death, findings are classified into specific forensic categories.

• Obscure autopsy
  • An autopsy where 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.
  • This occurs in approximately 5% of all forensic autopsies.
• Medical malpractice autopsy: specifically focused on investigating deaths suspected of resulting 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 a body was still alive at the time of having sustained damage as opposed to the damage having occurred 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 gasses such as 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 the onset of death.

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

The postmortem period is divided into 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 temporarily viable. In this period, they still respond to external stimuli, before cellular death occurs.

Supravital reactions

• Overview
  • Supravital reactions are certain physical functions that persist for some time after the onset of death.
  • Represents the interval between clinical death and molecular death
  • Provide specific clues regarding the time of death
  • Clinical significance: This window is critical for organ harvesting for transplantation; for example, the cornea must be harvested 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's muscle phenomenon, i.e., mechanical stimulation causes propagated excitation
• Up to 17 hours: pupillary response
• Up to 80 hours: motile sperm cells

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

Eye changes

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

Algor mortis

• 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 time since death

Postmortem caloricity

• A condition where 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/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

• Description: 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 passage of urine and/or feces.
  • 1–2 hours after death, ATP depletion causes permanent binding of actin and myosin, leading to muscle stiffness and the characteristic rigidity of rigor mortis.
  • Rigidity persists 1–2 days until proteolysis during decomposition breaks down muscle proteins, which leads to relaxation (secondary flaccidity)
  • Follows Nysten rule, progressing from the 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: develops to 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 (e.g., gras, a weapon)
  • 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, suicidal gunshot, and drowning

Livor mortis

• Definition: purple-red discoloration of dependent areas of skin not exposed to pressure that begins 20–30 minutes 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/shock and if a body is floating (e.g., in water)
• Location: blood pools in areas of dependency under the force of gravity ^[3]
  • Person died lying 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]
  • Lividity is evident on the ear lobes and the nail beds
  • Also occurs in visceral organs (e.g., lungs)
• Features
  • Redistribution
    • Lividity can be altered up to 6 hours after onset of death ^[5]
    • Afterward, it becomes permanent (fixation)
    • If the body is moved before fixation, new lividity forms (secondary lividity)
    • Eventually, lividity blends with putrefication discoloration
  • Blanching
    • Skin will turn white when applying pressure within the first ∼ 12 hours ^[6]
    • In fixed state, blanching is absent
  • Contact pallor
    • Pale areas of skin in dependant body parts that had contact with a surface or are under pressure
    • Pressure causes compression of blood vessels, which means that blood can not pool there
• 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 lividity
    • 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
    • Cerry 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)
• Post mortem clots: separation of red blood cells and plasma creates clots of plasma that resemble “chicken fat” and blackish-red erythrocyte clots that resemble “currant jelly”

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 one week of exposure to air, two weeks submerged underwater, and eight weeks of interment.

Autolysis

• Overview
  • Self-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, organelles
• Effects
  • Blister formation, skin seperation
  • Tissue softening

Putrefaction

Putrefaction is 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, thereby producing pigments, fluids, and gases, which lead to the typical signs of decomposition. Certain substances (e.g., strychnine, heavy metals, and carbolic acid) can delay the onset. Noticeable changes of putrefaction include:

• 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 marble patterns with green, purple, or blackish color
    • 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 a 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: due to autolysis and putrefaction, which cause destruction, digestion, and dissolution, solid tissues lose their form and turn into a soft, semi-liquid, or liquid mass
  • The larynx and trachea are affected first
  • Followed by:
    • Stomach and Intestine
    • Spleen
    • Liver
    • Brain
    • Heart
  • Late: skin, prostate in males, non-gravid uterus in females
  • Last: bone and teeth

Special forms of decomposition

• Mummification: Warm environments with extremely low humidity can cause bodies to mummify and resist decomposition.
• Adipocere: 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, immersions, 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, e.g., socks, belt, and bra)
• Tardieu spots: dark pinpoint spots develop in dependent areas (e.g., in the legs of a hanged person due to increased gravitational pressure)

Evidence of live birth

The condition of the lungs and the gastrointestinal tract can provide evidence of whether an infant 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. The test is, however, unreliable as 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's second life test: Air in the gastrointestinal tract provides clues as to how long an infant lived before dying. The further down there is air in the gastrointestinal tract, the higher the probability an infant survived 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 six hours after birth
  • Air in the entire large intestine: onset of death up to twelve hours after birth