Forensic Pathology Flashcards
Rigor mortis
-3-36 hours ~ Usually occurs approx 24-48 hrs uniformly.
After rigor mortis, a period of secondary flaccidity occurs.
Algor mortis
Change in body temperature to reach room temperature.
- Warm: 0-8 hours
- Cold: 8+ hours
Livor mortis
Pooling of blood post mortem. Can be either fixed or unfixed.
Putrefactive decomposition
- air and moisture exposure, especially warm
- Bacteria decompose, Bacteria at the cecum are usually first to invade.
- First seen as green discoloration in RLQ
Adipocere decomposition
Occurs in bodies submerged in water. Hydrolysis of lipids allows for a wax-like covering of the body.
Mummification
VERY HOT and VERY DRY
- no moisture of microbes, beetles, etc.
- or if body falls into a peat bog
Who can legally certify a death certificate for natural death?
MEs, coroners, justice of the peace, etc.
MEs are required to sign death certificate for which manners of death? (4)
Accident
Suicide
Homicide (lethal injection is considered homicide)
Undetermined
Cause vs. mechanism vs manner of death
Cause of death: disease or injury that produces the physiological disruption inside the body resulting in death
- example, a gunshot wound to the chest.
- comes from autopsy, disease/injury that initiated morbid events leading to death
Mechanism of death: physiological derangement that results in the death.
-Example due to the gunshot wound described above is exsanguination (extreme blood loss).
Manner of death: how the death came about. ME’s opinion
1) Natural
2) Accident
3) Suicide
4) Homicide
5) Undetermined
6) Pending
2 major roles of the ME
Assign a COD
Render an opinion as to manner of death
ME has no duty to families, they work for society at large.
Mechanical forces causing injury (6)
Abrasions Lacerations Contusions Incise wounds Gunshot wounds Blast injury
Thermal injuries (3)
Burns
Hyperthermia (heat cramps, heat exhaustion, heat stroke)
Hypothermia
What are the 5 major categories of injury caused by physical environment?
Mechanical force Thermal injuries Ionizing radiation Electrical injuries Atmospheric pressure
What 2 systems are mostly affected by radiation?
Hematopoietic and lymphoid systems
What is the first problem that occurs when radiation is given more than 0.15 sv?
Temporary sterility
Main sites of injury and main signs and symptoms for:
0-1 sv
1-2 sv
2-10 sv
10-20 sv
> 50 sv
0-1 sv: none, none.
1-2 sv: lymphocytes, moderate granulocytopenia and lymphopenia.
2-10 sv: bone marrow, leukopenia, hemorrhage, hair loss, vomiting.
10-20 sv: small bowel, diarhea, vomiting, fever.
> 50 sv: brain, ataxia, coma, convulsions.
Accurate death certification schema:
Immediate COD (mechanism) (pneumonia)
Due to:
(Proximate) COD (COPD)
Manner of death (natural)
3 types of wounds from blunt force trauma
Abrasion
Contusion
Laceration
Wounding formula
W = E x 1/T x 1/A x K
K is modifying factors (elasticity, etc)
E is energy transferred = 1/2 MV^2
T is period of energy transfer (time)
A is area of application of force
Contusion
A bruise that results from hemorrhage into soft tissues due to rupture of subcutaneous BVs by blunt injury.
What is the epidermis like in a contusion?
It is intact and therefore a contusion does not bleed externally, but may be seen from skin or internal organs.
What do yellow, blue/purple/red and brown bruises suggest in dating a contusion?
Yellow is most significant and its presence indicated the bruise is 18 hrs or older.
None of the others are helpful.
Abrasion
3 types of abrasions
A wound where the epidermis is injured. It bleeds externally, but not profusely.
- Brush (sliding/gliding)
- Impact
- Patterned (when abrasion reflects the surface of appearance of the instrument)
Stab wound
Sharp force creates a wound track that is greater thab the length (deeper than wide).
3 major categories of guns and their subtypes
Long guns
- bolt/lever action
- semiautomatic
- fully automatic
Smooth bores
Hand guns
- revolvers
- semiautomatics
What is the wounding formula for guns/projectiles?
KE = 1/2m x V^2
Velocity is much more important than mass
What is seen on entry wounds in:
Contact range
Intermediate range
Distant range
Contact range - marginal abrasion; soot/powder in depths of wound.
Intermediate range - marginal abrasion, powder/tattooing/stipping around wound
Distant range - marginal abrasion, no powder/tattooing/stipping, no soot/powder in depths of wound.
What is the inner and outer table separated by in the adult skull?
A diploe
How are entry and exit wounds described in the skull?
Entry wounds of outer table is sharply circumscribed, while the inner table is beveled.
If the buller has an exit wound, it is the opposite setup.
Low velocity leads to:
High velocity leads to:
Low - small entry, no exit (or small exit)
High - relatively small entry, big exit.
Who can certify unnatural causes of death?
forensic pathologist
justice of peace certification
Abrasion
- injured epidermis from friction scraping, direct pressure, or tangential blow
- ooze blood/serum and heals by scab
- no perfuse bleeding
Brush abrasion
- produced by grazing/sliding motion, tangentially applied force
- inspection reveals tools/heaps of tissue at wound margin opposite to direction of force
- superficial epidermal tears w/ superficial dermal hemorrhage
- Brush burns
Patterned Abrasion
Abrasion resembles surface of object used
Laceration
- Always blunt force trauma
- irregular skin tearing
Contusion
- bruise from rupture of subcut blood vessels that hemorrhages into soft tissue from a blunt force injury
- intact epidermis, no external bleed
- seen on skin or deep viscera
Severity of contusions depends on what?
- amount of force
- tissue vascularity
- tissue type (loose tissue = injured more)
- location of tissue (over bone = more severe)
- older age, liver cirrhosis, coagulopathies increase bleed
Incise wound
made by sharp object and is longer than puncture wound and less deep
GSW Contact wound character on inspection
dirt, powder grain, soot in depths of wound
GSW Intermediate wound character on inspection
stippling and powder tattooing pattern burned into skin
GSW Distant wound character on inspection
no tattooing, soot, or powder in wound
Mechanism vs Cause of death in GSW example
Mechanism: hemorrhage
Cause: Gunshot
