FSC401 Forensic Pathology Test 1

Administritiva and missinglaneous

-Medicine, anatomic pathology, forensic pathology

-Forensic pathology, forensic medicine

-Medical autopsy, forensic autopsy

What is the role of the coroner?

-A public official who is responsible for determining the cause of death

What is the role of the forensic pathologist?

-A medical doctor specializing in investigating the cause of death by performing autopsies, particularly in cases of suspicious, violent, or sudden deaths

What are the five questions in a death investigation?

-Who (identity of the deceased)

-When (date/time of death)

-Where (location of death)

-How (medical cause of death)

-By what means (natural causes, accident, homicide, suicide, or undetermined).

2 broad categories of goals of the autopsy

-Documentation

-Discovery

Cause of death

-Immediate cause of death (disease or injury that brings about cessation of life)

-Underlying (proximate) cause of death

Underlying cause of death example #1:

-Man shot in neck 9 years prior to his death by his brother

-Survived but bullet injured his spinal cord, leaving him paralyzed from the neck down

-Required a catheter and became prone to frequent bladder infections

-Recent infection traveled up to kidneys and he died

-Autopsy: Overwhelming kidney infection and tell tale signs of chronic quadriplegia and scarring around his remote neck injury

Cause of death:

1a. Acute pyelonephritis due to…

1b. Chronic indwelling urinary catheter due to…

1c. Quadriplegia

1d. Cervical spinal cord transection

1e. Gunshot wound to neck

Manner of death is still homicide if direct causal chain can be reliably established (“Domino effect”)

Cause of death statement

-Who format (causal chain; found on death certifications):

• 1A ____ due to 1B _____ 1C _____ and so on

• 2: Significant contributing factors, but not causally related to COD

-Descriptive format: A in the presence of B (ex: acute myocardial infarction in a man with acute cocaine intoxication)

-Therapeutic complication: A complicating B for the treatment of C

Pending cause of death

-May give the COD as “pending” after the autopsy if the COD remains unknown and further information may be required

-”Pending” COD could mean in needed from:

• Toxicology

• Histology

• Cardiovascular or neuropathological consultation

• Genetic studies

• Medical charts

• Police investigation

• Scene information, biochemical analysis, anthropologic examination

Mechanism of death

-Physiologic derangement/result of insult

-I.e. the physiological process that leads to death when one or more vital organs fail (due to injury, disease, or natural events)

Medico-legal autopsy

-Medical investigation on behalf of greater society to determine how and why its citizens die

-Performed under legislation of Coroner’s Act (not family consent)

-Once coroner takes jurisdiction over a body, the family essentially has no rights to the remains until the body is released

Goals of medico-legal autopsy

-Determine cause of death

-Determine mechanism of death

-Estimate time of death and/or timing of injuries

-Determine nature and mechanism of injuries

-Give opinions as to the nature of instruments or weapons that may have been involved in creating the observed injuries

-Trace evidence collection, etc.

Triangle of death

Natural disease ←→ injury ← → toxicity ← →

Five parts of the medicolegal autopsy

1. Assessment of scene and circumstances surrounding death

2. External examination of body

3. Internal examination of body

4. Interpretation of additional studies in context of case

5. Synthesis of medicolegal opinion

Manner of death

Natural, accident, suicide, homicide, undetermined

External examination

-General nutrition and development

-Hair colour, eye colour

Identifying features (documentation of tattoos, scars, etc)

-Examination of all body surfaces

-Document injuries, petechiae, etc.

-Collection of trace evidence

-Consider alternate light source examination

-Consider radiographic examination

Internal examination

-Y-shaped incision of torso

-Organ block (Letulle technique → an autopsy method that removes all the organs in one mass); weigh and examine individual organs

-Retract scalp, saw calvarium, remove brain and examine

-Consider special dissections

Additional tests

-Ancillary tests: A supplementary medical test or procedure that supports a primary diagnosis or treatment

-Tox results, histology, neuropathic consultation, etc.

Medicolegal opinion

-Autopsy is an integration of all info available and must be interpreted in the specific context of the case

-Injury/findings rarely stand alone

3 cardinal signs of death for postmortem changes

-Rigor mortis

-Algor mortis

-Livor mortis

Postmortem changes: What is decomposition and its pathways/processes?

-Decomposition is when dead organic substances are broken down into simpler organic or inorganic matter

-Putrefaction, mummification, saponification (adipocere)

Rigor mortis

-Stiffening of muscles that occurs after death.

-Temperature dependent (cooler = slower onset)

-Noticeable in small muscles first

-Lapses (passes off) after point of maximum stiffness

-Must be noted at scene

Livor mortis

-Aka lividity or postmortem hypostasis

-Pooling of blood after death (settling of blood)

-Position/gravity dependent (face up/supine or face down/prone)

-Fixed lividity: indicated longer postmortem interval

-Indicates position of body after death and whether it has been moved

Artifacts of lividity

-Tardieu spots (hemorrhages in skin and organs due to lividity)

-Its decayed blood vessels; blood vessels lined by cells which die bc of lack of oxygen → they die and as a result, fall apart → blood vessels become leaky

-Hypostatic artefacts may be misinterpreted as injury → these hemorrhages coalesce to form bruise-like marks on body

-When seen in the neck may be misinterpreted as strangulation → therefore, insistence that body is transported face up (on their back)

-Tardieu spots are confined to areas of intense lividity (unlike bruises)

Algor mortis

-Cooling of body after death

-Rate variable, dependent upon:

• Ambient environment temperature

• Temp of body before death

• Clothing and coverings

• Body surface area to mass ratio

Putrefaction

-Hot, humid weather

-Skin discolouration

-Marbeling: Due to proliferation of bacteria within superficial veins

-Bloating/gas formation: gas = bloating; fluid = purge (gas formation forcing decomposition fluids thorugh mouth and nose)

-Skin slippage (epidermal blistering and peeling; hair and nails detach)

Mummification

-Hot, dry

-Postmortem drying of body

-Skin is “leathery”

-Tissue is dehydrated

-Organs become desiccated

-Time course is variable

Can putrefaction and mummification coexist?

Yes, different parts of the body can experience different kinds of decomposition

-Ex: Mummification of hands and feet; putrefaction occurs on part of the body that is “more wet”

Adipocere

-Damp and no oxygen

-Saponification of tissues

-Waxy substance consisting chiefly of fatty acids and calcium soaps that is formed during decomposition of dead body fat in moist or wet anaerobic conditions

Postmortem taphonomy

-Env influences after death

-Most common: insects (maggots), carnivores (postmortem predation), humans (clandestine activity, dismemberment)

Approach to decomposed body

-Identification (dental comparison, surgically implanted instruments, DNA)

-Rule out injury (fractures, bleeding, bullets, etc)

-Determine cause of death

Classification of injuries

-Blunt force injuries

-Sharp force injuries

-Firearm (gunshot) injuries

-Asphyxial injuries

-Environmental injuries

Blunt force injuries

-Contusions (bruises)

-Abrasions (scrapes)

-Lacerations (tears)

-Fractures

-Fall vs assault

-Patterned injuries

-Descent from height

Contusions

-A region of injured tissue or skin in which blood capillaries have been ruptured (a bruise)

Abrasions

-A wound to the skin that occurs when the skin is rubbed or torn off

Laceration

-A cut or tear in the skin or soft tissue

-By sharp object (ex: knife → stab wound) or blunt force

-No skin is missing

Blunt facial trauma

-Fall or terminal collapse: Blunt trauma to face over areas of bony protrusion (localized)

-Assault: Blunt trauma to face is more widespread with great bruising

• Periorbital contusion (black eye)

• Lacerated lips

• Facial fractures

Patterned injuries

-Impact of instrument on the skin causing a distinctive pattern or impression

-Generally a combination of: abrasions and contusions

-May permit wound-weapon matching

Common patterned injuries

-Motor vehicle collisions: tire marks, seat belt, dicing (safety glass; side door glass in all passenger vehicles)

• Dicing: Toughened or tempered glass; tempering puts the outer surfaces into compression and the inner surface into tension →.stressors cause glass to break and crumble into granular chunks

-Homicide: bitemarks, toolmarks (‘tram tracks’)

• Toolmarks: Compression pushes blood out to side, vessels can’t carry blood fast enough so they burst

• Bitemarks: Swab for DNA, if lucky you’ll get a foreign DNA sample (not deceased’s)

Descent from height

-Impact and deceleration related injuries

-Distribution of trauma dependent on position of impact and secondary to impact sites

-Common patterns: Axial intrusion of spinal column, open comminuted long bone fractures, mutilating head injuries

Sharp force injuries

-Stab wounds

-Incised wounds (cut/slash)

-Chop wounds

-”Defensive” wounds