Lividity postmortem is the purplish or reddish purple discoloration of skin and organs that occurs after death as a result of blood buildup in dependent bodily parts that may be seen through the skin.
It is the:
(i) bluish-purple or purplish-red discoloration,
(ii) which appears after death,
(iii) on the most dependent parts of the skin,
(iv) as a result of blood pooling in the capillaries and tiny veins (rete mucosum) of the dermis’s most superficial layers,
(v) as a result of gravity
Synonyms of Postmortem Lividity
Postmortem lividity also known as:
- Cadaveric lividity,
- Darkening of death,
- Livor mortis (L. Livor, blueness; mortis, death),
- Postmortem hypostasis,
- Postmortem lividity,
- Postmortem staining,
- Subcutaneous hypostasis,
Mechanism of Postmortem Lividity
After death, the blood in its liquid form gravitates into the toneless capillaries and veins of the ‘rete mucosa’ in dependent sections of the body, causing capillary dilation and which imparts discoloration to the affected area through the skin.
Lividity emerges within 1 to 3 hours following death. It will begin as a succession of mottled patches that progressively grow in size and then merge between 3 to 6 hours following death, becoming completely formed and fixed by 6 to 8 hours.
In general, if applying pressure with a thumb blanches the region, the lividity is not permanent and the duration after death is shorter than 8 hours. If the region does not blanch, lividity has set in and the period since death has passed more than 8 hours. Fixation is caused by haemoglobin diffusion through capillary walls and persistent staining of tissues.
Conditions in which postmortem lividity is absent
Postmortem Lividity is not always present in the body, and it may be absent in the young, aged, clinically anaemic, or individuals who have perished from massive haemorrhages. It may also be concealed in people with dark skin, jaundice, or certain dermatological problems.
Medicolegal Importance of Postmortem Lividity
- Can determine the time since death.
- Can determine the deceased’s posture at the time of death.
- Can determine the cause of death.
- It might be misinterpreted as a contusion.
The color of hypostasis and its extent also bears forensic significance.
- Cherry red hypostasis is an indication of carbon monoxide poisoning.
- Brick red of cyanide poisoning
- Septic deaths due to Clostridium Perfringes results in bronze hypostasis.
- Pinkish hypostasis is seen in bodies preserved in cold temperatures and in individuals dying from hypothermia.