POSTMORTEM CHANGES

The changes that occur in the body after death are helpful in finding out approximate time since death and these changes are known as Postmortem changes (changes occurring after death in the body). These changes can be classified into following types-

1. Immediate changes
2. Early changes
3. Late changes

1. Immediate changes-

• These changes comes under somatic death which means cessation of nervous system, respiratory system and circulatory system.
• Loss of  sensory and motor functions.
• Loss of reflexes and tonicity of muscles.
• Pupils are dilated.

2.Early changes-

• It appears after 3-4 hours of death.
• Changes in eyes-  after death eyes loses its luster and corneal reflex (after about 6 hours) and becomes opaque.  The retinal columns show fragmentation of blood columns.  The shape of the pupil also changes after death from circular to oval, triangular or polygonal if pressure is applied. Cornea becomes completely hazy after 10-12 hours of death due to decomposition.  Formation of Taches noire (formation of two small yellow triangles) is seen in eyes after death if eyelids remain open for 3-4 hours of death. This happens due to drying and desiccation of sclera giving rise to triangular shaped discolored area.

• Changes in Skin-  After death skin becomes pale white due to stoppage of circulation of blood and drainage of blood from the capillaries and vessels. The skin loses its elasticity. The lips become dark or brown colored due to drying up.
• Cooling of body-  It is also called Algor mortis. After death (in 1-2 hours of death) the body starts losing its heat to environment and attains the temperature of its surrounding (takes about 12-15 hours). The rate of cooling is not uniform but it can surely give an indication about time since death. The outer body temperature falls more rapidly than the inner core temperature.
• Time since death can be found out roughly by the following formula-
• Time since death = normal body temperature (37degree C) – Rectal temperature ÷ Rate of fall of body temperature per hour

Algor mortis depends on following factors-

• Age– The body of elderly and kids cool rapidly than adult bodies.
• Condition of body – fat people bodies retain heat for longer as compared to timid and weak people.
• External environment- a body in a proper ventilated, big room cools faster than a body present in small room with still air. A dead body in water cools faster.
• Manner of death- body cools faster when a person dies of severe chronic diseases than the person dying of sudden, accidental, violent deaths.

Postmortem Caloricity- in this condition, the temperature of the body remains high after death for about 2 hours. Instead of cooling the temperature of the body rises for initial 2 hours due to certain infectious diseases  like septicemia (heat is produced by infective organisms). It is also seen in death due to sunstroke, cholera, tetanus and strychnine poisoning.  In some tropical countries, due to higher environmental temperature the body temperature can also rise.

Medicolegal Importance of Algor Mortis

• It is a sign of death.
• It helps in estimation of time since death.
• Fast cooling of dead body delays the process of rigor mortis and decomposition. If heat is preserved in the body for longer time then Algor and Rigor mortis starts early.

Postmortem Staining/ Lividity/ Hypostasis- It is also known as livor mortis or suggillation. It is bluish or purplish discoloration resulting from gravitational settling of blood into the capillaries and small veins in the dependent parts of the body. It appears after 1 hour of death as small discolored patches and  after 6 hours of death it gets completely fixed. PM staining depends on the lying position of the body. If a body is lying in supine position, it starts to appear on the neck and then to back except on the parts directly in contact with the ground. If a body is lying in prone position, intense lividity is seen in front and Tardieu’s spots are also seen. In case of hanging, the PM staining will be most marked in the legs, hands, forearms, external genitalia.

Medicolegal importance of Postmortem Staining-

• a sign of death.
• time since death can be roughly calculated.
• it tells the posture of body after death.
• it can also indicate the moving of body to another position after death. In early phases of PM staining when small and patchy, it may be confused with bruises.

3. Late changes

• Cadaveric rigidity or Rigor mortis- It is a condition after death in which the body muscles start to become stiff and rigid with some degree of shortening. It is also known as death stiffening.
• It occurs immediately after muscles lose the power of contractility.
• The phase of primary relaxation of muscles continues for about an hour then it is followed by stiffening or rigidity.
• Soon after death, ATP production stops, which is responsible to provide energy for contraction and relaxation of muscles. As ATP production decreases the power of contraction and relaxation of muscles also stops. The muscle fibers consists of myofibrils. In myofibrils there are two portions- actin & myosin. Due to decreased concentration of ATP fusion of actin and myosin takes place which leads to muscle stiffening. This stiffening is called rigor mortis or cadaveric rigidity.
• Rigor mortis appears in involuntary as well as in voluntary muscles. It occurs first in involuntary muscles then in voluntary muscles.
• Onset & duration- rigor mortis starts after 1-2 hours of death in tropical countries like India and takes about 9-12 hours to develop from head to foot, then stays for another 12 hours and takes another 12hours to pass off.
• Appearance of Stiffening- it first appears in heart muscles and left chambers of heart are more affected than the right. Then, it follows a definite pattern of setting in the muscles of eye lids, then in jaw, facial muscles, neck, thorax, upper limbs, abdomen, lower limbs and lastly in small muscles of fingers and toes.
• The rigidity disappears in the same order of appearance and stays the most in lower limbs.

Factors affecting Rigor mortis-

i)Environmental temperature- it comes early at high temperature and leaves early. It comes slow at cold temperature and stays late. 

ii)Violent exercise before death may increase the onset and passing off of Rigor.

iii)Body built– it comes early in weak and thin and comes later in heavy built bodies and stays for late.

Medicolegal importance of Rigor Mortis-

• It is a sign of death indicating molecular death of muscles.
• It helps in finding out time since death roughly.
• It indicates the position of body at the time of death.

Some of the conditions which may commence Rigor Mortis-

• Cadaveric spasm (instantaneous rigor)- the muscles before death in contracted state remains so after death also.
• Heat stiffening- when body is exposed to more than 65 degrees Celsius then, the rigidity is produced much more marked in rigor.
• Cold stiffening- this is seen when body is exposed to freezing temperatures, the tissues become frozen and stiff.
• Gas Stiffening or putrefaction- caused by accumulation of gases in body causing false rigidity in muscles.

Putrefaction 

• It is a process of breakdown of complex organic body tissues into simpler inorganic compounds due to autolysis or saprophytes. It is brought about by release of enzymes after death.
• It happens after disappearance of rigor mortis.
• Common bacteria’s producing putrefaction are clostridium welichi, bacillus proteus and large number of streptococci.
• The production of foul smelling gases and color changes are main features of it.
• The first external evidence of putrefaction is greenish discoloration of abdominal skin over iliac fossae. This process of discoloration is due to the conversion of hemoglobin present in blood to sulphmetheamoglobin by the action of hydrogen sulfide from intestines to tissues. It occurs after 1-3 days after death in winters and after 6-12 hours in summer.
• Production of foul smelling compounds- as the process of putrefaction begins after death, the body starts emitting an unpleasant smell due to the production of hydrogen sulfide, marsh gas, ammonia, carbon dioxide. All this happens because of the activity of micro organisms.
• The process of putrefaction gets altered and is replaced by formation of adiopocere,  sometimes which is a waxy looking substance with greasy feel and may be of white or slight yellowish color. It has a soapy feeling and melts on heating. It happens due to postmortem hydrolysis of fats.

• Mummification –The desiccation or drying of the dead body where the soft tissues present on the body shrivel up. The skin becomes dry, leathery and is adherent to bones, and is dark brown in color. The facial features are preserved. The time taken by a dead body to mummify is not exactly known, but it may take from three months to a year or two.

Factors affecting Putrefaction-

• Putrefaction is achieved more rapidly in hot weather as compared to winters, more in humid conditions and develops slowly in water. If air movements are more, putrefaction is more.
• Bodies of kids putrefy faster than adults. Elderly people putrefy slowly as compared to others as moisture is less. People died of diseases like septicemia putrefy early than others. The odor is more of like the smell of old cheese than that of a decomposed body.

Time since Death

After death, it becomes very important to rule out the time since death for this several things should be kept in mind. After conduction of proper autopsy the Postmortem changes like cooling of body, post mortem staining, rigor mortis should also be kept in mind.