Transcript Forenisc Pathology

Forensic
Pathology
Medicolegal investigation of death
“The psychiatrist knows nothing and does
nothing. The surgeon knows nothing and
does everything. The pathologist knows
everything… but is always a day too late.”
-TRADITIONAL MEDICAL MAXIM
Coroners vs. Medical Examiners
• Coroners- elected position, more often
found in rural areas.
• Medical examiners- physician (usually a
pathologist)
When are autopsies performed?
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Sudden and/or unexpected death
Public health concern (ex. Mysterious disease)
If someone dies unattended by a physician
Family asks for an autopsy
If an autopsy is not required by law, the next-of
kin must give permission
• Laws vary from state to state.
Example
• Someone witnesses a suicide
• Know ID of person, time of death, cause of
death.
• Why do an autopsy?
– Show contributing factors to the suicide
• Terminal disease
• Pregnancy
• Drugs/alcohol
Example
• Someone observes a car accident in
which someone else leaves the roadway,
hits a tree and is killed instantly.
• The autopsy may reveal contributing
factors:
• Blackout
• Myocardial infarction
• Alcohol/drugs
Parts of an autopsy
• External examination
» Look for bruising, cuts, wounds, etc…
• Internal examination
» Weigh organs
» Check for abnormalities
» Preserve in formaldehyde
• Microscopic examination
» Histology – study of tissues
• Toxicology report
» Blood, urine, bile, fluid from the eye
» Looking for meds, drugs, alcohols, poison
Cause of Death
• What caused life to cease?
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Ex. Blunt trauma to the head
Ex. Bullet to the heart
Ex. Heart attack
Ex. Kidney or liver failure
Ex. Cancer
Ex. Asphyxiation
• Long list
Manner of Death
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Natural
Homicide
Suicide
Accident
Undetermined
Jobs of the ME
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1. ID the deceased
2. Time/date of death
3. Cause/manner
4. Protect property of dead
5. Notify next of kin
Estimating Time of Death
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1. Rigor mortis
2. Livor mortis
3. Algor mortis
4. Stomach contents
5. Vitreous humor
6. Changes due to decomposition
7. Entomology
8. Botany
Rigor Mortis
touch test
• Warm and not stiff: not more than a couple
of hours
• Warm and stiff: dead between a couple of
hours and a half day
• Cold and stiff: dead btw a half day and two
days
• Cold and not stiff: dead more than two
days
Rigor mortis
• ATP fuels muscle contraction- lack of ATP
triggers rigor
• ATP breaks the link btw actin and myosin,
• ATP depleted after death, actin and
myosin stay locked
• appears within 1-3 hour
Affects Rigor mortis
–Body temperature and
environmental temp.
–Metabolic rate
–Starvation
–Physical activity
–Poison
Cadaveric spasm
• Body or body part “Frozen” in position at time of
death
• Fast rigor due to lack of ATP
– struggle or chase
– Exercise
– Shooting a gun
– “Death grip” during drowning
Timeline of Rigor Mortis
• appears within 1-3 hours
0-12 hours: Body stiffens, starting with jaw, neck,
face/fingers/toes, trunk, arms, and legs
12-24 hours: Entire body stays rigid
24-36 hours: Relaxation starting with jaw, neck,
face/fingers/toes, trunk, arms, legs
Livor mortis
PML= postmortem lividity
- Purple coloring
- Blood settles closest to the ground
- Appears within 30-60 min. of death
- No discoloration if
• tight clothing
• Object pressing against body
- Can tell if body has been moved since death
Problems with livor mortis
• Variations between races
• Blood loss
• Anemia
Other color changes
• Bluer color caused by being cyanotic (not
enough O2)
– Can be caused by respiratory illness or
cyanide poisoning
• Cherry red color- from carbon monoxide
poisoning
Algor mortis
- Drop in body temperature after
death.
- Avg. of 1-1.5 °F per hour
- Measure in liver/rectum
Algor Mortis affected by
»Location of body
»Body size
»Clothing
»Weather
»Temp @ death
ex. Fever from illness
ex. Elevated temp from drug use
ex. Head injury
Rigor, livor, algor
• Only useful for 24-48 hours
• Rigor- body relaxes
• Livor- becomes fixed
• Algor- body reaches ambient temperature
Stomach contents
• If food is in the stomach, the degree of
breakdown of the food can help provide an
estimate of time of death.
• 90% of what we eat is out of the stomach
in 2-3 hours
Decomposition
• A) Autolysis- softening/liquefying of the
body caused by enzymes released by cell
organelles after death.
• B) Bacterial- breaks tissue into
liquids/gases
Stages of Bacterial Decomposition
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Initial Decay
Putrefaction
Black Putrefaction
Butyric Fermentation
Dry Decay
1. Initial Decay
• Initial Decay- externally OK, but internally
decomposition starts.
• Discoloration of surface blood vessels in upper
abdomen as bacteria spread.
• Color changes from red…dark red…
purple…green
• 1st sign- green over right lower abdomen
– cecum-pouch at start of large intestine
• E.Coli bacteria are normally found in the
body but are kept in check by the immune
system.
• After death, the bacteria are no longer
held in check and multiply rapidly.
• E.Coli spreads from the intestines and
enters the bloodstream.
• Bacteria form CO2 : gas causes bloating
and eventually rupture of intestines.
2. Putrefaction
• Cadaver swollen w/ gases, odor of decay
(within 2-3 days)
• Hair loosens
• Fluid from mouth and nose
Putrefaction
• Liver/brain—“swiss cheese” (from bubbling
gases)
• Loose skin falls off
• Body swells, tongue/eyes protrude
• Breasts and genitalia balloon
3. Black Putrefaction
• Flesh is soft w/ black areas. Strong odor
4. Butyric fermentation cadaver drying out.
– Some flesh.
– Cheesy odor.
– Ventral surface moldy.
• 5. Dry Decay
Vitreous humor
• Eye jelly dehydrates
• Potassium levels change
• Needle and syringe to suction the eye
Problems w/ vitreous humor
– K+ levels vary from front to back
– Need every drop of vitreous humor—can
disrupt retina if pull to hard with syringe
– Increased heat, humidity, fever… can falsely
raise K levels
– Variation between 2 people or between 2
eyes of the same person
Entomology
• After death, flies lay eggs on the body.
• The eggs develop into larvae (maggots),
and then pupa, and then adults.
• The time it takes to progress through each
stage is predictable, and can be used to
determine when the eggs were first laid
and thus, when the victim died
Tasks
• 1. Preautopsy meeting
• 2. Photos
• 3. Reexamination
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White light
UV
Laser
Alternate light source
Remove clothing, jewelry
Tasks
• 4. Fragile (trace) evidence
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Fibers
Hairs
Glass
Debris
• 5. Vulnerable evidence
collect saliva in bite marks
take control sample near bite mark
Tasks
• 6.Swabs
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Vagina
Penis
Oral
Anal
Nasal
Tasks
• 7. x-rays
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Broken bones
Metallic objects
Healed fractures
Dental x-rays
• 8. Gunshot residue
• 9. Scrape fingernails
Tasks
• 10. Wounds
• 11. Pubic Hair combing
• 12. Collect standard hairs
• Pulled from head
• Need 50-100 hairs
• 13. Casts
• Make 3-D casts of bite marks, entrance holes, cuts
Tasks
• 14. ID photos
• Face, tattoos, scars
• 15. Fingerprints
• 16. Autopsy
• A. Injection sites, look in orifices
• B. Y shaped incision
• C. Inspect organs
» heart., lungs, liver, kidneys
Autopsies
“This is the place where death rejoices to
teach those who live.”