Postmortem Changes and Time Since Death | Anatomy2Medicine
Postmortem Changes and Time Since Death

Postmortem Changes and Time Since Death

    • Postmortem staining : synonyms (MCQ)
      • Suggilation ,postmortem hypostasis ,subcutaneous hypostasis  ,livor mortis ,cadaveric lividity ,darkening of death.

 

  • Vibices ,Postmortem ecchymoses ,Death spots MCQ)
  • tiny, spot-like, oval-to-round, bluish black hemorrhages of postmortem origin

 

      • These form because of postmortem mechanical rupture of subcutaneous capillaries and smaller vessels— predominantly veins
      • After death, blood pools up in the most dependent parts of the body, causing increased intravascular pressure in the capillaries of these regions.
      • This is the main cause of the rupture.
      • Vibices are thus formed in most dependent parts of the body. (MCQ)
    • Tache noir de la siderotiques  (MCQ)
    • seen within  3 hours of death on sclera
    • two yellow triangles of desiccated discoloration
    • They appear on each side of the cornea, with their bases resting on the circumference and apices jutting into the inner and outer canthi

 

  • Later these become brown and then black.
  • They indicate that the eyes were open after death.

 

    • Cooling of the body is also known as Algor mortis
    • Rate of cooling helps in determining time of death

 

  • Post mortem caloricity (MCQ)

 

      • rise of temperature after death is seen in

 

  • Heat stroke
  • Pontine haemorrhage
  • Septicaemia.

 

    • In India, generally the fall in rectal temperature after death occurs at a rate of : (MCQ)

 

  • In summers -0.75°F/hour.
  • In winters -1.5 °F/hour.
  • Postmortem lividity  (MCQ)

 

    • unlikely to develop in a case of drowning in a fast flowing river

 

  • For postmortem lividity to develop, the dead body must be in a fixed position for some length of time.

 

  • Since in a fast flowing river, the body would keep turning about, it is difficult for postmortem lividity to develop.

 

  • Rigor mortis

 

      • first starts in eyelids (MCQ)
      • Rigor mortis appears first in involuntary muscles followed by voluntary muscles. (MCQ)
      • The first organ traditionally thought to undergo rigor mortis is heart.
      • Within voluntary muscles, rigor mortis typically has a proximo-distal progression, i.e. it starts in the facial muscles and then spreads down – to neck, upper limbs and lower limbs in that order.

 

  • Rigor is initiated when the ATP concentration falls to 85% of the normal (MCQ)
  • Rigidity of the muscles is at maximum when the level declines to 15% of the normal

 

    • Cadaveric spasm  (MCQ)
    • It is instantaneous in onset
    • It is confined to a small group of muscles

 

  • It occurs only in voluntary muscles

 

    • In rigor mortis, the muscle both stiffens and shortens(MCQ)
      • Shortening in various organs can cause different phenomena
      • Rigor in iris causes pupil to change in size, making its postmortem position an unreliable indicator of toxic or neurological conditions during life.
      • Rigor in heart may be mistaken for ventricular hypertrophy (can be resolved by measuring total weight of the heart)

 

  • Rigor in dartos, seminal vesicles, prostate —postmortem extrusion of semen from urethral meatus.

 

      • Rigor in erector pili muscles -pimpling or “goose-flesh” appearance of the skin. (MCQ)
      • May also give a false impression that the beard grows after death.

 

  • Rigor in pregnant uterus may cause   postmortem delivery.

 

    • In electrocution, rigor mortis appears early and passes early (MCQ)

 

  • Sommer’s movements are changing of position of limbs after death allegedly due to contraction of muscles due to rigor mortis (MCQ)

 

    • Rigor mortis in a fetus does appear but may be so feeble as to be unappreciable

 

  • Breaking of rigor mortis usually occurs during transportation of the body

 

    • Immediate rigidity of a group of muscles without passing into a stage of primary relaxation is called Cadaveric spasm ,Instantaneous rigor
    • Rigor mortis (High yield facts for AIPGMEE,AIIMS, DNB CET)
      • Onset of rigor is accelerated and its duration shortened when the environ mental temperature is high
      • Onset is relatively more rapid in children and the aged than in muscular young adults
      • It develops early and passes quickly in deaths from septicaemia or from wasting diseases
      • Rigor mortis is early in onset and is of shorter duration after prolonged muscular activity
    • Color changes of putrefaction are first observed in Right iliac fossa (MCQ)
      • Right iliac fossa is affected first, as caecum is located there.
      • Putrefactive bacteria form hydrogen sulfide there, which converts haemoglobin into sulphmethemoglobin, which is greenish in color

 

  • Thus the first change is greenish discoloration of right iliac fossa.
  • Putrefaction of internal organs (A very very High yield MCQ for AIIMS,AIPGMEE,DNB CET)

 

      • Softer organs putrefy earlier
      • Organs which contain more blood putrefy earlier
      • Organs nearer to the source of bacteria putrefy earlier
      • Organs composed of muscular tissue and those containing large amount of fibrous tissue resist putrefaction longer than the parenchymatous organs.
    • Putrefaction is delayed in carbolic acid poisoning (MCQ)
    • Casper’s dictum : (MCQ)
      • time  taken  for same   amount of putrefaction to occur when the body is in air, water and buried in earth is in the ratio of 1:2:8
    • The correct sequence of putrefaction (earliest to last) of the internal organs is in the following order (JIPMER Nov 2014 MCQ)
      • Larynx and trachea (First to putreify)
      • Stomach, intestines, spleen
      • Liver, lungs
      • Brain
      • Heart
      • Kidney, Bladder, Uterus
      • Skin, muscle, tendons
      • Bones. (Last to putreify)
    • “watery” organs putrefy earlier.
    • “Drier” organs like tendons and bones putrefy latter.
    • Prostate is the last organ to putrefy in males (MCQ)
    • Mummification  (MCQ)

 

  • refers to desiccation of the dead body

 

      • Mummification is likely to occur in warm and dry weather, with hot air blowing constantly
      • In favorable circumstances, it will take 3 months to a year time for  body to mummify completely
    • In India, colliquative putrefaction is seen after about 1 week (MCQ)
      • Colliquative putrefaction is the name given to a very late stage of putrefaction, when the walls of abdomen soften and burst due to pressure of gases formed inside.
    • Adipocere is likely to occur in warm humid climate (MCQ)

 

  • Entomology of cadaver helps best in determining: time since death
  • Stumer’s formula  (MCQ)

 

      • calculate the time since death
      • takes into account potassium concentration in the vitreous humor
      • During life, potassium concentration is low in the vitreous humor but much higher in peripheral tissues such as retina.
      • After death potassium from peripheral tissues starts diffusing in the vitreous raising its concentration.

 

  • Stumer’s formula

 

        • Time since death = 7.14 x [K+] – 39.1

 

  • Madea’s formula

 

        • Time since death = 5.26 * [K+] – 30.9
    • Section 107 of the Indian Evidence Act (IEA). (MCQ)
    • This is generally  known as presumption of continuance of life

 

  • Burden of proving death of person known to have been alive within thirty years
  • When the question is whether a man is alive or dead, and it is shown that he was alive within thirty years, the burden of proving that he is dead is on the person who affirms it.

 

    • Section 108 of the IEA (MCQ)
      • This is known as Presumption of Death

 

  • Burden of proving that person is alive who has not been heard of for seven years

 

      • Provided that when  the question is whether a man is alive or dead, and it is proved that he has not been heard of for seven years by those who would naturally have heard of him if he had been alive, the burden of proving that he is alive is [shifted to] the person who affirms it.
      • It is important that while claiming of property by legal heirs , presumption of Life and Death become important
    • Postmortem luminescence in a decaying body is due to:

 

  • light emitting bacteria such as Photobacterium fischeri

 

luminous fungi such as Armillaria mellea (Ramsbottom).