Post Mortem Changes Flashcards

1
Q

What is death

A

The irreversible failure of the cardiovascular system - but exceptions do occur

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2
Q

What happens after cardiovascular failure

A

Failure of oxygen delivery to the tissues resulting in cellular death

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3
Q

What happens after cellular death

A

Energy production ceases and the body cools

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4
Q

What happens after the body cools

A

Circulating blood becomes stagnant and settles under the effects of gravity.

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5
Q

What does the failure of the usual body defences cause

A

It will no longer be able to inhibit the proliferation of bacteria so putrefaction ensues

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6
Q

What can significantly affect the body

A

Post mortem predation by animals

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7
Q

When is the best opportunity for timing death

A

First 18 hours after death

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8
Q

What can cause inaccuracy

A

Inherent biological variability

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9
Q

What is the mainstay in the first 12 hours after death

A

Measurement of body temperature

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10
Q

What type of curve is produced in the rate of body cooling

A

Sigmoid

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11
Q

What can influence the rate of body cooling

A

Body temp at time of death (usual temp?)

Is the body clothed (nature of clothing?)

Natural insulation of the body

Convection currents

Environmental temperature

The length of the plateau phase of the cooling curve

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12
Q

What is the time range in time of death calculations under the most favourable conditions

A

+/- 2.5 hours

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13
Q

How many degrees does the body cool per hour (rule of thumb)

A

1oC

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14
Q

Can the rate at which the stomach empties be used as a means of measuring the time of death or the time since the last meal?

A

NoAs too many factors influence the rate at which the stomach empties

But it can offer information on what the deceased last ate depending on the condition of the material remaining

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15
Q

What can influence the rate at which the stomach empties

A

Nature/amount of food

Solids vs liquids

Stress

Certain medication

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16
Q

What is rigor mortis

A

Stiffening and shortening of muscle fibres leading to rigidity of the musculature and fixation of the joints

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17
Q

Why does rigor mortis occur

A

Due to the reduction of ATP within the muscles after death

All muscle fibres are affected

Theoretically detected in smaller muscles before larger muscles

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18
Q

When does rigor become apparent

A

5-7 hours after death

Fully established 8-12 hours after death

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19
Q

When does rigor dissipate

A

Dissipates in line with ensuing decomposition and frequently absent by 36 hours after death (body returns to a flaccid state)

20
Q

What is the problem with using rigor mortis in timing death

A

Biological variability

21
Q

When can rigor mortis potentially be used

A

First couple of days after death

22
Q

What can affect the development of rigor

A

Ambient temperature

Cadaveric Spasm (grasping of objects)

23
Q

What other methods have been investigated in estimating the time of death

A

Measurement of the level of potassium ions in the vitreous humour of the eye

24
Q

What causes decomposition and putrefaction

A

The action of bacterial micro-organisms

Process begins at death, but takes a period of time to become detectable

25
Q

What variables needs to be considered in regards to decomposition and putrefaction

A

Ambient temperature

Humidity

“Cleanliness” of the environment in which the body lies

26
Q

What colour appears after 2-3 days in abdominal skin

A

Greenish discolouration

27
Q

What occurs 1 week after death

A

Blister formation and tissue swelling, including gas formation in body cavities

28
Q

Why can vascular marbling be seen

A

Due to putrefaction of the superficial veins in the skin

29
Q

What can be resistant to putrefaction

A

Certain organstheir persistence can be valuable for identification purposes

30
Q

What is mummification

A

Process of “dry” decomposition, with desiccation of the body and a relative lack of bacterial involvement so Body essentially “dries out”; the facial features and hands/feet may become rigid

31
Q

What type of bodies are prone to mummification

A

Infant bodies

32
Q

What causes adipocere formation

A

Induced by the alteration of fatty tissue within the body into a greasy/waxy or brittle material which frequently remains attached to the bony skeleton and may retain the body structure to some extent

33
Q

Where does adipocere formation tend to occur

A

Damp or wet enviroments (e.g. bodies recovered from water)

34
Q

What is skeletonisation

A

When all of the soft tissues of the body have completely degraded

35
Q

What can cause skeletonisation to vary

A

Exposure to meat-eating animals (post mortem animal predation, e.g. rats)

Dipterous larvae

36
Q

What type of radioisotopes have been used to age bones

A

Strontium

Polonium

37
Q

What is postmortem hypostasis

A

Pooling of stagnant blood in dependent regions of the body under the influence of gravity

38
Q

Where is postmortem hypostasis usually apparent

A

External aspect of the body

Can be seen in internal organs as well

39
Q

When does postmortem hypostasis begin

A

As soon as the circulation of blood ceases but takes time to become visible

Usually about 1-2 hoursFully established by 6-12 hours

40
Q

What will occur to the body surface where pressure is applied

A

Compression of the blood vessels, preventing ingress of blood, demonstrated by areas of “pressure pallor” within hypostasis

(e.g. a body lying on its back would be expected to have areas of pallor on the upper back and the buttocks as these are the main areas upon which the body mass rests)

41
Q

When is postmortem hypostasis useful

A

In ascertaining the position of the body after death and can indicate if the body has been moved after death (so long as movement occurred after lividity was established)

42
Q

What is the normal colour of hypostasis

A

Pink/Purple

43
Q

What does cherry red hypostasis indicate

A

CO poisoning

44
Q

What does red/brown hypostasis indicate

A

May be seen with methaemoglobin (caused by certain chemicals or drugs)

45
Q

Give some examples of post mortem artefacts

A

1) Alteration or damage to the body occurring after death - may mimic genuine processes occurring in life
2) Resuscitation (cardiopulmonary resuscitation)
3) Animal predation (land and sea)
4) Traumatic injury (e.g. dead person run over by a motor vehicle or dropped during removal from the scene of death)

46
Q

When are post mortem aretefacts commonly seen

A

Bodies recovered from water due to the movement of the body in the water