postmortem change

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Postmortem changes

• By Dr Magde Boukhatwa
• 8-11-2018

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Early Changes

• Primary Flaccidity complete loss of tone.
• Muscle may be still reactive for hours (focal
  twitching).
• Pale skin and conjunctiva.
• Face may remain blue/red.
• Loss of sphincter action pass urine, semen,
  regurgitation of food.

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Changes

• Changes in the eye
• Changes in the skin
• Cooling of the body/ Algor mortis
• Post mortem lividity /Hypostasis
• Rigor mortis/Cadaveric rigidity

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Cooling of the body

• After death, the body becomes an inert substance,
  it will lose heat until it becomes in equilibrium
  with the surrounding environment.

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• Cooling and PM interval
• Determination of the time of death by body
  temperature is estimated by using the following
  formula
• Time since death 37ºC - rectal temperature (ºC)
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• N.B The rectum must always be examined before
  inserting the thermometer. In case of possible
  sexual assaults, swabs should be taken before
  inserting the thermometer.
• It is very difficult to determine accurately
  because there are many factors affecting the rate
  of cooling.

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• Factors affecting the rate of cooling of the body
  after death
• 1- External environment.
• 2- Posture of the body.
• 3- Obesity.
• 4- Clothing.
• 5- Age.
• 6- Edema.

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• 7- Body temperature at the moment of death
• - Body cools slower than normal in cases of
  raised body temperature at the moment of death
  as
• Pontine hemorrhage. Sun stroke.
  Severe infections. Excess heat
  production in convulsions.
• - In contrast, cooling is rapid in death
  associated with hypothermia as massive hemorrhage
  or shock.

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Changes in the eye

• Corneal Changes
• Loss of Clear Glistening
• Dry, Cloudy and opaque
• Loss of reflexes
• Light reflex abolished
• Intra Ocular tension falls, eye balls become
  flaccid and sink in the orbit
• Blood flow in the retina becomes dotted and
  segmented look.

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• Optic disc looks pale.
• Pupils fully dilated in the early stage and
  constrict later due rigor mortis.
• Brownish discoloration of the sclera due to
  cellular debris and dust

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Changes in the Skin

• Loss of its translucency.
• Pale and Ashy white appearance.
• Loss of Elasticity.
• Wounds will not gape if it is inflicted after
  death.
• Wounds caused during life will retain their
  characteristic features.

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Rigor Mortis

• Lack of oxygen no energy no ATP glycolysis
  lactic acid acidic cytoplasm actin and
  myosin bind.
• Stiff Muscle.
• Factors affects Rigor Mortis.
• Level of glycogen.
• Level of lactic acid.
• Body built.
• Temperature, weather.

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Rigor Mortis

• Starts in small muscle around eyes and mouth,
  jaw, fingers.
• Then spreads from head to legs.
• Estimated time of death
• In face 1-4 hours.
• Limbs 4-6 hours.
• Increase in strength for the next 6-12 hours.
• Decomposition starts.
• Secondary flaccidity from 24-50 hours.

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Cycle of Rigor Mortis
putrefaction
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• Rigor mortis affects both voluntary involuntary
  muscles including muscles of the heart, blood
  vessels, iris erector pilae muscles of the skin
  (giving goose skin appearance).

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Medico-legal imp of rigors mortis

• Medico-legal importance of rigor mortis
• 1- It is a sure sign of death.
• 2- Estimation of the time passed since death (see
  above).
• 3- It fixes the dead body at its position
  indicating if it has been changed after rigor has
  set in.
• 4- It may suggest the cause of death, which is of
  rapid onset in death following exhaustion
  (tetanus, strychnine poisoning or violent
  deaths).
• 5- It may be mistaken with other conditions of
  stiffness .

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Cadaveric spasm

• It is stiffening of a group of voluntary muscles
  performing an action (strong contraction) at the
  moment of death while whole body in a state of
  primary flaccidity. This continues until rigor
  mortis sets in.
• It occurs in deaths associated with extreme
  nervous tension such as
• i- Suicidal cases, the weapon used is firmly
  clenched in the victim's hands.
• ii- In drowning, the victim grasping weeds or
  gravel.
• iii- Homicidal cases, the victim may firmly
  grasping hairs or a portion of clothes belonging
  the assailant. In smothering, the victim teeth
  may clench a piece of the palm of the assailant.

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• Medico-legal importance of cadaveric spasm
• 1- It indicates that death was associated
  with great nervous tension.
• 2- It indicates the muscles in physical
  activity at the time of death.
• 3- It indicates the manner of death
  whether suicidal, homicidal or accidental.

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Differences between rigor mortis cadaveric spasm
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Heat stiffness

• It is shortening of the muscle fibers due to the
  effect of heat resulting in flexion of the limbs
  (pugilistic or boxer attitude) that will remain
  stiff until putrefaction sets in.
• - It occurs due to coagulation of the muscle
  proteins in cases of burn.
• - Rigor mortis does not develop in such muscles
  and the stiffness persists until the coagulated
  proteins are liquefied by decomposition process.
• - It is either ante-mortem or postmortem
  phenomenon.

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boxer attitude
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• Cold stiffness
• It is due to freezing of inter and intra
  cellular fluids of the tissues and freezing the
  synovial fluids in the joints.
• If the temperature rises gradually, cold
  stiffening disappears and followed by appearance
  of rigor mortis with rapid spread and remains for
  a short period.

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Post Mortem Hypostasis (Lividity)

• Definition
• It means discolorations or staining of the skin
  and organs after death due to accumulation of
  fluid blood in the dependent parts of the body.

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• No circulation, relaxation of blood vessels.
• Blood moves to dependent area.
• Positioning of body supine, prone, on side, on
  head, hanging.
• Pink-blue color of the dependent area.
• May not be apparent in infants, elderly, anemic.
• Difficult to see in dark skin, jaundice.

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• Blanching
• Around face (not asphyxia)
• Color
• Pink deep pink blue purple
• Cheery pink in carbon monoxide poisoning
• Dark red in cyanide poisoning
• In hypothermia pink around large joints
• Movement of body and change in lividity!

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Blanching
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• Deep blue colour of hypostasis is seen in death
  due to poisoning by
• A. Potassium cyanide
• B. Phosphorus
• C. Aniline dyes
• D. Carbon monoxide

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• Colour of post mortem lividity (hypostasis)
• Normal Bluish pink which later turns into
  bluish purple
• Carbon monoxide Bright cherry red
• Cyanide Pink
• Phosphorous Dark brown
• Nitrates Reddish brown
• Chlorates Chocolate brown
• Hydrogen sulphide Bluish Green
• Aniline Deep blue
• Opiates Black

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Bright cherry red
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Medico-Legal Importance

• It is a reliable sign of death.
• It gives the information about the position of
  the body at the time of death.
• Time since death can be estimated.
• Colour suggest the cause of death.
• Distribution of lividity may give the information
  about the manner of death.

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Putrefaction

• It is the last stage that takes place in the dead
  body with its resolution from organic to
  inorganic state.

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• Visible 3-4 days.
• Green discoloration in the right iliac fossa.
• Marbling of skin linear branching patterns of
  brown discoloration of skin.
• Blistering, skin sloughs off.
• Gas formation, swelling of body face, abdomen,
  breast, genitalia.

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• Mechanism
• 1- Autolysis
  
• 2- Bacterial actions

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1- Autolysis

• Proteolytic, glycolytic, and lipolytic enzymes
  released from the cells act on body tissues
  their softening and liquefaction (auto digestion
  of organs).
• Autolysis occurs early in the brain and
  parenchematous organs (liver, lung, spleen,
  heart).

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2- Bacterial actions

• 2- Bacterial actions
• A-Aerobic pathogenic organisms present prior to
  death in relation to certain diseases.
• B- Anaerobic organisms (B Coli, Cl. Welchi and B.
  Proteus) present normally in intestinal tract
  invade mucous membranes shortly after death and
  spread all over the body via blood vessels which
  are good channels for their spread nutrition.
  They produce enzymes that breakdown body tissues
  with gas evolution.

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• The liberated gases are a mixture of bad odorous
  gases like hydrogen sulphid, ammonia, methane
  with a bad odor froth coming from mouth and nose.
  
• When putrefaction advances, there is complete
  digestion of the soft tissues of the dead body
  with liberation of bad smell gases, liquids and
  salts leaving the body skeleton (skeletonization).

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Purge fluid
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Marbling
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Factors affecting the rate of putrefaction

• 1- Age Newly born breast fed (due to scanty
  organisms) and old age (due to dryness of tissues
  decrease humidity), putrefy very slowly.
• 2- Causes of death
• Putrefaction more rapid in bodies dying from
  infectious diseases as septicemia.
• Putrefaction is delayed in arsenical poisoning
  due to dehydration and the poison hinders the
  growth of putrefactive organisms.

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• 3-Temperature
• The optimum temperature for putrefactive bacteria
  is 37C.
• Putrefaction is more rapid in summer and delayed
  in winter.
• Temperature less than 40C more than 50C delay
  putrefaction for long periods.
• 4- Moisture
• Putrefaction is delayed in dehydrated bodies,
  while in cases of CHF or general anasarca (edema)
  or bodies recovered from water putrefaction will
  be rapid.
• Organs with high moisture content as brain
  putrefy more rapid than dry tissues as nails
  hair.

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• 5- Air
• Most of putrefactive organisms are aerobic. Thus
  bodies buried under compact soil putrefy later
  than bodies buried in spongy soil or sandy soil.
• Bodies submerged under water putrefy more slowly
  than those kept in the air, and putrefaction is
  more rapid under stagnant water than running
  water and in fresh than in sea water.
• 6- Manner of burial
• Putrefaction is delayed in bodies buried in
  sealed coffins and deep in the soil as Christians
  do.

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• 7- Blood content
• Putrefaction is rapid in the liver (high blood
  content which is good medium for putrefactive
  bacteria).
• The gravid uterus putrefies more rapid than
  non-gravid uterus.
• The putrefaction is delayed in case of death due
  to blood loss.
• 8- Mutilated bodies
• Bodies sustaining multiple stab wounds putrefy
  early due to many opening for entrance of
  bacteria and air. - Putrefaction is
  delayed in amputated limbs as there are away from
  bacteria of the body and the amount of blood is
  small.

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Adipocere formation

• Definition
• It is a PM change replacing putrefaction. It is a
  grayish waxy substance formed by the
  decomposition of soft tissue in dead bodies
  subjected to moisture.( or kept under water)
  
• Mechanism
• It is due to hydrogenation of the non saturated
  body fats (palmitic and oleic) into saturated
  (stearic) hard fat forming a dipocere which is
  yellow, greasy, wax-like substance with a rancid
  smell.
• Site
• It develops usually in cheeks, breast, buttocks
  and abdomen. It is common in females. It may
  occur in some body areas while other areas show
  putrefaction.
• Time
• It begins to form after 3 weeks, completed after
  6 months.

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• Medico-legal importance of adipocere formation
• 1- It denotes long submersion under water.
• 2- Estimation of the time passed since death
  (from 3 weeks to 6 months).
• 3- Identify the person as it preserves the body
  features.
• 4- It gives an indication about the cause of
  death as it preserves the pre-existing injuries
  or trauma.

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Mummification

• Definition
• It is PM change replacing putrefaction. It is
  natural process for preservation of the body by
  natural causes (high temperature, dry atmosphere
  and sandy soil).
• Mechanism
• It is due to dryness of the body by the high
  temperature and absence of the humidity (as in
  Upper Egypt) prevents growth of organism and
  preserves the body.
• Site
• It starts in the most exposed parts of the body
  (lips, tip of nose, fingers toes) and then the
  process extends to the rest of the body.
• The body is shriveled, odorless and often black
  in color. The skin is hard, leathery and adheres
  to the shrunken tissue.
• Time
• It starts to occur after 3 weeks from death and
  completes in one year after death.

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• Medico-legal importance of mummification
• 1- Estimation of the time passed since death
  (from 3 weeks to 1 year).
• 2- Identify the person as it preserves the body
  features.
• 3- It gives an idea about the cause of death as
  it preserves the pre-existing injuries or trauma.

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Home work

• why is post mortem interval important?