L2: Post-Mortem Changes Flashcards
What are Post-Mortem Changes?
- Cooling of the body
- Postmortem Hypostasis “Lividity” or “Livor-Mortis”
- Postmortem Rigidity or “Rigor Mortis “ “Stiffness of Death “
- Putrefaction or Decomposition
Def of Post-Mortem Cooling
- Defined as gradual cooling of dead body until it comes in equilibrium with surrounding temperature.
Rate of Post-Mortem Cooling
- The average rate of heat loss is about 1-1.5°C/h
- Rate of cooling is not uniform
Mechanism of Post-Mortem Cooling
- During life, there is balance between heat production and heat loss.
- After death, heat production stops and body loses heat.
when does dead body attain environmental temperature?
- Dead body attains environmental temperature “external surface cooling” in about 16-20hs from death.
what are factors that affect Post-Mortem Cooling?
- Environmental temperature (Major factor)
- Media of disposal
- Mode and cause of death
how does media of disposal affect Post-Mortem Cooling?
In case of drowning in running water
- Rate of heat loss is double that in the air
(2-3° C /h).
How does environmental temperature affect Post-Mortem Cooling?
- The dead body cools rapidly, when difference between environmental temperature and that of corpses is great as in the winter.
What types of deaths cause slow Post-Mortem Cooling?
occurs in deaths due to
* Infectious diseases
* Heat stroke (fever).
What types of deaths cause fast Post-Mortem Cooling?
occurs in deaths due to
- Long wasting illness as T.B
- or shock.
MLI of Post-Mortem Cooling
- It is a sign of death.
- It helps in rough estimation of time of death.
what are other names for Postmortem Hypostasis?
“Lividity” or “Livor-Mortis”
Def of Postmortem Hypostasis
- It is bluish or purplish discoloration or staining of most dependent parts of body skin and internal organs after death.
- It is called “Postmortem staining” or “Darkening of death”.
Mechanism of Postmortem Hypostasis
Onset of Postmortem Hypostasis
- Usually begins immediately after death
Shape of Postmortem Hypostasis
- Begins as small mottled patches on dependent parts of body within 1-3 hs.
- Mottled patches coalesce with each other to form uniformly stained large areas
Color of Postmortem Hypostasis
Has same color as blood that can be mistaken for bruises.
Blanching of Postmortem Hypostasis
Fixation of Postmortem Hypostasis
Absence of Postmortem Hypostasis
- Hypostasis does not develop over areas of contact flattening
- This phenomenon is known as contact pallor as vessels in these areas remain pressurized and the blood is compressed out.
Postmortem Hypostasis as a sign of death
- Hypostasis is a sure sign of death
- it is one of the best proofs for somatic death.
MLI of Postmortem Hypostasis
- A sign of Death
- Important in Determination of Time passed since death
- Important in determination of Cause of death
Importance of Postmortem Hypostasis in detection of time passed since death
- It helps to estimate time passed since death from
formation, extension and fixation of postmortem staining. - There is early onset hypostasis in case of a person who died after. prolonged recumbent position
Importance of Postmortem Hypostasis in detection of casue of death
It gives an idea about the cause of death
- From its position
- From its color
Postmortem Hypostasis in cases of hanging
The site of distribution and pattern of lividity depend upon the position of body after death
- Hypostasis is observed over dependent (Lower limbs, External genitalia, Distal parts of forearms and hands)
Postmortem Hypostasis in cases of drowning
Postmortem Hypostasis in natural death
Bluish purple
Postmortem Hypostasis in hemorrhage & Severe anemia
Very faint
Postmortem Hypostasis in asphyxia
Deep blue
Postmortem Hypostasis in cases of CO Poisoning
Red color
Color of Postmortem Hypostasis and what it indicates
DDx of Postmortem Hypostasis
In certain cases, isolated patches of lividity remain separate from large areas of lividity and may resemble antemortem bruises.
Compare between PM lividity & AM Bruises
what is another name for Postmortem Rigidity?
“Rigor Mortis “ or “Stiffness of Death
Def of Postmortem Rigidity
- It is a condition of progressive stiffening and rigidity of both voluntary and involuntary muscles,
what precedes and follows Postmortem Rigidity?
- Preceded by period of primary flaccidity
- Followed by secondary flaccidity.
Mechanism of Postmortem Rigidity
Timeline of Postmortem Rigidity
- 2 hours after death
- 12 hours after death
- 48 hours after death
Postmortem Rigidity 2 hours after death
- Rigor mortis starts to appear 2 hours after death in small muscles then spreads from above downwards.
- It affects firstly muscles of eye lids, and then jaw, muscles of face, neck and trunk, followed by muscles of upper limbs and then lower limbs.
Postmortem Rigidity 12 hours after death
Rigor mortis takes 12 hours to be completed all over body “Fixed body”.
Postmortem Rigidity 48 hours after death
- Rigor mortis disappears completely in about 36-48 hours after death.
- The rigid muscles start to soften gradually in same order of their occurrence
testing of Postmortem Rigidity
what are factors affecting Postmortem Rigidity?
MLI of Postmortem Rigidity
- Rigor mortis helps to estimate time passed since death by marching of rigor.
- Rigor mortis can give information about position of the body at time of death.
Site of Cadaveric Spasm
- It is usually limited to a single group of voluntary muscles
- frequently involves the hands
Def of Cadaveric Spasm
- It is stiffening of specific group of voluntary muscles, immediately after death, without being precedod by stage of primary flaccidity.
Examples of Cadaveric Spasm
DDx of Cadaveric Spasm
Def of Putrefaction or Decomposition
- It is a biological process caused by growth of bacteria on organic matter of dead body transforming it into inorganic state.
Mechanism of Putrefaction or Decomposition
Onset of Putrefaction or Decomposition
Putrefaction starts after
- 24hs after death in summer
- 48hs in winter.
External signs of Putrefaction or Decomposition
