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Forensics > Postmortem Changes > Flashcards

Postmortem Changes Flashcards

1
Q

Name 5 changes occurring 0-3h after death.

A
  • warm and flaccid
  • pallor but livor mortis soon observed (hypostasis)
  • bladder may empty
  • gastric contents regurgitated
  • trucking of retinal blood vessels
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2
Q

Name 3 postmortem changes occurring 3-8 h after death

A
  • warm and rigid
  • Rigor Mortis
  • livor mortis begins to develop
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3
Q

Factors influencing rigor mortis ? (4)

A
  • exercise (faster)
  • age: appear and disappear faster in children
  • emaciated: difficult to determine
  • temp: hotter = faster
  • low muscle glycogen levels ( faster )
  • electrocution faster
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4
Q

Name 2 PM changes at 8 - 36h

A
  • cold and rigid

* algor mortis fully sets in

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5
Q

How long does algor mortis take to set in?

A

8 -12 h skin, core temp longer

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6
Q

What is the best estimator of time since death in first 24 h?

A

PMI (post mortem interval)- most accurate during intermediate phase where it drops linearly. Uses algor mortis. Pmi= body temp at death - body temp at exam.

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7
Q

Name 3 PM changes after 36 h

A
  • Cold and flaccid
  • putrefaction and decomposition
  • skeletalisation
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8
Q

Name the 3 stages of putrefaction

A
  1. Initial decay (36/72 h - 1w) (abdo green discolor; bloat, blister, marbling of BVs on limbs and trunk, purge fluid)
  2. Black putrefaction (up to 1 mo) (organs liquefy - temp dependant)
  3. Dry decay then skeletonisation
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9
Q

If hypostasis colour is Cherry pink, what pathology can be suspected?

A

Carbon monoxide poisoning

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10
Q

If hypostasis colour is brick red, what pathology can be suspected?

A

Cyanide poisoning (and smell like hazelnut)

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11
Q

If hypostasis colour is golden brown, what pathology can be suspected?

A

Clostridium perfringens

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12
Q

Which biochemical factor can be used to estimate PMI?

A

Potassium concentration in vitreous. Increases PM. Must be carried out up till 5-7 days

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13
Q

Onset of rigor mortis?

A

3-4 hours after death. Face 1-4 h , limbs 3-6 h

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14
Q

When is rigor mortis fully established?

A

8-12 hours (textbook: 18 h )

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15
Q

Which term describes muscle stiffness with onset immediately at death, usually finding items gripped firmly in hands of deceased?

A

Cadaveric rigidity

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16
Q

In which patients may lividity be absent? (3)

A

• Extremes of age
• anemic
. Severe blood loss

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17
Q

Name 5 factors that may influence algor mortis

A
  • Obesity (good insulator)
  • emaciation (faster)
  • Body posture
  • body temp at time of death
  • site of reading body temperature
  • presence of clothing, type of material, position on body
  • environmental temp and conditions - movement of air, humidity
  • immersion water
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18
Q

Onset of decomposition?

A

3-4 days

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19
Q

Initial appearance of putrefaction?

A

Green discolor r iliac fossa ant abdominal wall. 3-4 days pm

20
Q

Name 4 organs or tissues resistant to putrefaction initially

A

Prostate, uterus, tendons, ligaments

21
Q

Describe process of decomposition (8)

A

• Green discolor right iliac fossa ant abdominal wall (cecum)
• marbling blood vessels - haemoglobin decompositions
• generalised skin discoloration
• superficial skin layers lose cohesion , blisters cont red/brown fluid form
• when blisters burst, skin sloughs off
• bloating face, abdo , breasts, genitals (gas)
. Protrusion eyes and tongue (increased int pressure ) causing purge fluid to leak from lungs, blood-stained
. Soft tissues liquefy
Then skeletalization.

22
Q

What is adipocere?

A

Chemical change in body fat, hydrolysed to waxy soap -like compound

23
Q

Conditions causing adipocere?

A

Wet conditions : immersion in water or bury in moist environment

24
Q

Most useful method of estim time of death?

A

Henssge’s nomogram

25
Q

Henssge’s nomogram relies on which 3 measurements?

A
  • Body temp
  • ambient temp
  • body weight
26
Q

Difference between putrefaction and autolysis?

A

Both processes of decomposition.
Putrefaction is septic destruction soft tissues due to bact, wherees autolysis aseptic chemical process caused by intracellular changes. (own digestive endogenous Enzymes) (first appear as cloudy cornea )

27
Q

When does livor mortis become fixed?

A

8-12h

28
Q

Name 5 negative signs of death

A
  • No pulse
  • cessation of respiration
  • loss of corneal and light reflexes
  • fixed unreactive pupils-mid-dilated
  • cessation normal bodily functions
29
Q

Name 5 early pm changes

A
  • Supravital reactions (false positive signs) - mechanical (zsakos phenomenon patella, localised muscle bulge biceps) and electrical excitability of muscles, chemical stimulation of iris
  • pm fluid loss: dry skin, clouded and dry corneas, loss eye-globe tension
  • algor mortis
  • livor mortis
  • Rigor mortis
  • cadaveric spasm
  • biochemical changes: increased potassium vitreous
30
Q

Name 4 late pm changes

A
  • Putrefaction
  • autolysis
  • mummification
  • Adipocere (saponification)
31
Q

How long do supravital reactions persist?

A

12-15h pm

32
Q

What is the term to describe a patellar reflex pm?

A

Zsako’s phenomenon (supravital reaction)

33
Q

Name 2 examples of mechanical excitability of muscle as supravital reactions

A

Zsako’s phenomenon and localised muscle bulge biceps

34
Q

Name 3 signs of pm fluid loss

A
  • Dry skin
  • clouded and dry corneas (“tache noire)
  • loss eye globe tension
35
Q

Name 4 ways heat is least lost in algor mortis

A
  • Radiation (infrared rays)
  • convection (transfer to moving molecules eg air/liquid)
  • conduction (physical contact)
  • evaporation
36
Q

Rule of thumb for pmi?

A

Temperature loss 1° c /h during first 24h

37
Q

Name 3 phases of pmi

A
  • Initial: lag period o,5-3h
  • intermediate: drop linearly
  • Terminal: drop slows as core approach that of environment
38
Q

3 most accurate Sites of measure core temp in order?

A
  1. Rectum
  2. Liver
  3. Tympanic
39
Q

Name 4 factors affecting lividity

A

• Skin colour- less perceptible dark
• quantity blood in system - anemia, haemorrhage
. Length of time body lies in same position
• absent on areas exposed to pressure

40
Q

Name 5 differences between hypostasis and bruising

A
  • Hypostasis mottled in beginning but then coalesce vs Bruise rarely cover large area with uniformity
  • diffuse and regular engorgement of dependent area vs over any area body
  • horizontal margin vs discoid irregular
  • intravascular vs extravascular (infiltrate subcut tissue) on incision
  • gravity dependant positioning vs anywhere on body (pressure dependant, )
  • non-contact pressure areas vs contact areas
  • bruising associated with abrasions
41
Q

Which rule states that when there’s free access to air, a body decomposes twice as fast than If immersed in water and 8 times faster than if buried in earth

A

Casper’s rule

42
Q

In Which conditions does mummification occur?

A

Dry and hot conditions (dessication instead of putrefying )

43
Q

Name 4 postmortem artifacts

A
  • Animal predation
  • pm gas bubbling : right ventricle, leptomeningeal vessels
  • pm blood clots
  • artefacts caused by preparation: undertakers fracture, embalming (injec sites, change body colour)
44
Q

Which pm artefact is related to poor handling of body, causing subluxation of lower c spine from Tearing of the intervertebral disc at C6-c7 ?

A

Undertaker’s fracture

45
Q

What is a pugilistic stance?

A

Boxer-like posture of flexed elbows and knees and clenched fists due to shrinkage body tissues and muscles due to dehydration caused by heating.

46
Q

What is Parchmenting?

A

Skin being compressed blanches then dries out pm. Typical under ligature marks in hanging deaths.

Forensics (9 decks)

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