Lividity refers to the bluish-purple discoloration of skin when dead.

It's a standard sign associated with livor mortis, one in all the four post-mortem stages of death, together with wanness Mortis, algor mortis, and rigour mortis. Livor mortis is characterised by lividity and happens during hours when death.

Lividity happens as a result of the guts isn't any longer pumping blood throughout the body and, consequently, gravity pulls the blood down, leading to the pooling of blood at the lowest purpose within the body.

Lividity differs according to cause of death. Discolouration of the body differs according to the types of cases. Through this, time of death and position of body could also be determined in cases where mode of death is hanging, asphyxia etc.

How Does Liver Mortis Determine Time of Death?

Post-mortem lividity is one of the important signs of death; it's also called the “darkening of death” because shortly after death, in from 20 beats to 2 hours usually purple-red blotches begin to appear on the skin.

Within the first3- 4 hours after death, these lurid blotches may be blanched out by the pressure of the galette against the skin only to return when the croquette is removed.

The time of death is occasionally extremely important. It's a question nearly always asked by the investigating officers, occasionally with a touching faith in the delicacy of the estimate.

Determining the time of death is extremely difficult, and delicacy is insolvable.

Colorful systems have been tried to find out the time of death. These include the study of physical, chemical, biochemical and enzymatic exertion that occurs in a dead body.

The darkening of death is a physical change, which can be useful for calculating TSD.

Post-mortem examination hypostasis is a bluish-grandiloquent or purplish-red discolouration which appears under the skin in the most superficial layers of the dermis of the most dependent corridor of the body after death due to capillo- venous distention.

It's also called posthumous staining, subcutaneous hypostasis, livor mortis, cadaveric rage, suggilations, vibices and darkening of death.

The intensity of the color depends upon the quantum of reduced haemoglobin in the blood. In case of violent haemoglobin loss before death, the blood has deep purplish red in colour.

It's due to the cessation of rotation, deflation of blood in blood vessels, and tendency to sink by force of graveness.

The reduced amount of haemoglobin in the blood will determine the intensity of the colour of cadaveric lividity. When haemoglobin is reduced to a large extent blood becomes a deep purplish blue colour stain.

The colour of livor mortis is due to the following reasons:

(1) Dying tissue oxygen dissociation of take place and this continues until equilibrium is reduced between oxygen tension in capillaries and surrounding tissue.

(2) Reflux of venous blood from the venular and the capillaries which adds to the blueness.

Lividity could gift all told bodies however it will clearly see in truthful folks than in dark folks. Depends upon the position of the body stain is gift.

If the body is in its supine position, the lividity is going to be gift on the neck, and therefore the then adjoins the complete back with the exception of the elements directly ironed on. Hypostasis is typically marked within the lobes of ears and within the tissues beneath the nails of the finger.

Pink and white is also seen on the face, thanks to variable vasodilation within the skin. If the body is in prone position, the lividity appears in the loose connective tissues in front, the colour is intense and Tardieu spots are common.

The mode of death will determine the distribution and discolouration of lividty on the body

Asphyxial Death

It is a condition caused by interference with respiration or due to lack of oxygen in respired air causing unconsciousness or death.

Asphyxial death can occur due to many reasons like traumatic hanging, asphyxia, mechanical asphyxia, postural asphyxia, and toxic, pathological, iatrogenic.

Asphyxia has similar features such as smothering, suffocation, strangulation, or chest compression. Lividity will shows dark or pale purple in colour. 

For example:

Hanging

Hanging is the form of asphyxia which is caused by a ligature which encircles the neck, and the constricting force being the weight of the body.

A body suspended during hanging will develop hypostasis over distal parts of upper and lower extremities, whereas a body facing downwards shall present with congested face and conjunctiva which can sometimes be misinterpreted as signs of asphyxial deaths. Postmortem staining is like stocking and glove distribution.

Drowning

Drowning is a form of asphyxia due to aspiration of fluids into air passages, caused by immersion in water or other liquid. Complete immersion isn't necessary, for immersion of the   nose and mouth alone for a sufficient period can beget death from drowning. 

Posthumous staining is generally set up on the face, upper part of the casket, hands, lower arms, bases, and the pins, as the body generally floats face down, buttocks up, with legs and arms hanging down in front of the body.

Hypothermial Death

When a body is set up in a cold terrain one of the main important forensic view is whether the cause of victims death is due to hypothermia or not.

Hypothermia can lead to complete failure of your heart and respiratory system and ultimately to death. Normal body temperature is around98.6 F (37 C). Hypothermia (hi- Poe- THUR- me- uh) occurs as your body temperature falls below 95 F (35 C).

Death due to violent cold wave (hypothermia) or the refrigeration of a lately deceased body will produce a bright pink rage. The ultimate color can also be produced if the area of the body was covered by wet apparel.

The body is taken from the cold water as the wet skin allows atmospheric oxygen to pass through and also at low temperature hemoglobin has a great affinity for oxygen. This may be marked most over large joints dependent areas.

Poisoning Death

Carbon Monoxide Poisoning 

Carbon monoxide poisoning occurs when carbon monoxide builds up in your bloodstream.  When carbon monoxide is in the air, your body replaces the oxygen in your red blood cells with carbon monoxide.

This can lead to serious kerchief damage, or indeed death. Thus cherry red colour staining is present. Brain with cherry red staining, pink lungs with normal audile signs and largely fluid and bright pink blood due to carboxyhemoglobin conformation.

Hydrogen Sulphide Poisoning

At higher concentrations (1000Y2000 ppm), it produces rapid death with systemic toxicity, which is thought to be related to the inhibition of cytochrome oxidase.

Hydrogen sulphide poisoning is infrequently encountered in medical examiner practice. Most H2S deaths that have been reported occurred in association with exposure to sewer gas, which contains H2S.

More rarely, industrial exposures have been described. The lividity stain is normally greenish blue. The greenish blue discolouration is due to the sulfhemoglobin formation in the blood.

Conclusion

Lividity is the gravitational cooling of blood in the dependent parts of the body, both externally in the skin capillaries and venules but also in the internal organs.

Here in the study we analysed the different modes of death which includes asphyxia that is death occurred due to stoppage of respiratory system and lividity observed here is well developed and it is bluish purple discoloration.

From the above analysis we could identify that using lividity we could estimate the time of death ,the posture of body when it comes to blanching any body which is in contact with a firm surface, blanching occurs, cause of death which would be very useful in forensic investigation.