Intermediate Change-POSTMORTEM LIVIDITY

Synonyms - Postmortem Hypostasis
- Postmortem Staining
- Livor Mortis
It is a bluish or reddish- purple discolouration due to capillo-venous distention with blood, at the undersurface of skin of the dependant parts of the body, due to settling of the blood due to the pull of the gravity, when circulation to keep the blood in motion ceases.
Formation - when the body is left undisturbed without change of its position, the staining starts appearing in small patches at the dependant parts of the body, by the end of the first hour after death.

Fixation - After complete formation of the postmortem staining, if the body is still undisturbed for a period of another 5 to 6 hrs, then the staining over the area gets fixed.

Ø Fixation of postmortem staining is not due to intravascular coagulation of the settled blood. Very little coagulation of blood is seen in the small veins and capillaries. This is due to liquefaction of the postmortem clots in the smaller vessels and capillaries due to the action of fibrinolysin, liberated from the vascular endothelium at the time of death as a part of the death reaction. So there is free oozing of blood from the margins of the incision.
Ø Lividity also occurs at the dependant parts of all internal organs.
Ø The staining becomes discoloured, once decomposition starts in the body.
Ø It is an intravascular phenomenon hence there is no extravasation of blood in the area.
Ø Due to excessive loss of blood (Antemortem or Postmortem) lividity may absent.
Ø

Medico legal importance of Livor Mortis

a) It is a sign of death
b) Time passed after death can be roughly assessed
c) It indicates the posture of the body and the consequent cause of death.
· eg:- in hanging lividity appears in Lower limbs, lower part of upper limbs and in neck above the ligature.
d) From the colour of the Lividity cause of death can be predicted
· In death due to HCN poisoning the colour of the postmortem staining is Cherry red.
· In KCN and NaCN the colour is brownish.
· In Aniline or CO2 poisoning – deep blue
· In CO poisoning – pinkish
· In Phosphorous poisoning – dark brown

e) Postmortem staining, particularly when patchy and small in the early phase of its formation, may be confused with bruise.