According to the ‘Law of Progressive Change’ everything in this universe changes with time. And this is also applicable after the death of an organism. Human body shows a lot of changes during life as well as after death. The changes that occur in the body after death are termed as postmortem changes.
Before discussing postmortem changes let’s first talk about what death is. So, death is not a phenomenon but a process. The process of death starts with somatic death [the process of cessation of the tripod of life i.e., the cessation of nervous system (coma), respiratory system (asphyxia) and circulatory system (syncope)] and then follows molecular death i.e. ultimate death of all cellular entities.
After undergoing the process of death, the human flesh undergoes numerous changes some may take just after death while some may take few hours to days. The process of postmortem changes are almost similar in all the death cases and hence the changes can help us to determine a lot about the cause, nature and time of death.
Postmortem Changes In A Dead Body
Postmortem changes are are categorized into three types i.e.,
- Immediate Changes
- Early Changes
- Late Changes
1. Immediate Changes
As the name suggests, these changes occur immediately in the deceased, due to somatic deaths. The changes generally include:
- Insensibility– It refers to the loss of sensation (perception of touch, pain, temperature, power to move etc.). But these changes are not conclusive of death as they are common signs for certain physiological conditions like epilepsy, vagal inhibition, electrocution, etc. The symptoms can be taken conclusive only when a flat EEG (Electroencephalogram) is obtained for continuous five minutes.
- Respiratory Arrest– It is characterized by complete stoppage of breathing. Death is conclusive only when there is a complete absence of breathing for continuous three to five minutes, because cessation of breathing can also occur in Cheyne-Stokes breathing, in drowned or in newborn infants.
- Circulatory Arrest– It is the complete cessation of heart. A flat ECG (Electrocardiogram) for continuous five minutes is conclusive of death.
- Suspended Animation– It is the condition in which the vital functions (heartbeat and breath rate) are at such a low pitch that they are undetectable by clinical examinations. It is mistaken as death but the person can be revived after a few seconds through resuscitative techniques, hence called apparent death.
2. Early Changes
These changes occur within 12-24 hours due to the molecular death and include:
- Pallor Mortis– The skin becomes pale, ashy white in color and loses elasticity. Dryness of lips is observed which gives them a darker appearance.
- Changes in Eye– After death the eyes lose their luster and shows following conditions such as Loss of corneal reflex, Corneal opacity, Flaccidity of eyeball, Dilated pupils, Rise of potassium in vitreous humour, Taches noires (brownish discoloration of exposed sclera).
- Algor Mortis– It refers to the cooling of the body after death. It is one of the most prominent signs of death. After death the body stops producing heat and starts to cool down by conduction, convention and ration till it attains equilibrium with the environment. The temperature is measured by a chemical thermometer (thanatometer) which ranges from 0-50ºC.
The rate of cooling depends upon the factors like age of the deceased, clothings, place or medium where the dead body was found, atmospheric temperature, condition of body, etc.
- Livor Mortis– It also known as postmortem lividity which is defined by discoloration of skin and organs after death. This occurs due to accumulation of blood in the toneless capillaries and small veins of the dependent parts of the body. The color of lividity is bluish-purple to purplish-red due to deoxyhaemoglobin and the intensity of the color depends on the cause of death. The site of distribution and pattern of lividity depends upon the position of the body after death. Sometimes lividity is confused with bruises due to the presence of isolated patches separated from large areas of lividity. But they can be differentiated on careful examination.
- Changes in Muscles– After death three stages of muscle changes are observed.
- Primary Relaxation (flaccidity)– All the muscles of the body get relaxed immediately after death. However the muscles can still be made to react to electric shocks.
- Rigor Mortis– It is the postmortem rigidity of the muscles of the dead. This occurs due to the chemical changes in the muscle protein filaments- actin and myosin.
- Secondary Relaxation (flaccidity)– The molecular death of actin and myosin fibres results in loosening the stiffed body and the muscles do not respond to electric stimuli.
3. Late Changes
The late changes (after 24 hours of death) of the dead body includes the decomposition and decay which occurs in following stages:
- Putrefaction– It is the final stage of resolution of the body into inorganic matter and is a certain sign of death. It is initiated by two processes i.e., autolysis (release of lytic enzymes from the cells which liquify the tissues of the body) and bacterial action (enzymes released by bacteria action on carbohydrates, fats and proteins and decomposes the body). This process depends strictly on the atmospheric conditions where the deceased is present.
This stage leads to- external changes (change in skin color, marbling effect, foul smell, and appearance of maggots), colliquative putrefaction changes (liquefaction of all the body tissues) and internal changes (putrefaction of organs).
- Adipocere Formation– It is also called saponification. In this process the liquid fats get converted into saturated solid fats (adipocere) which are waxy in nature. This conversion is facilitated by the bacterias from the intestine and the environment.
- Mummification– Sometimes the process of putrefaction gets arrested due to the dehydration or drying of the cadaver, which mummifies the body preserving the natural body appearance and general facial features. It is very common in dead infants and not common in adults, but may appear occasionally in buried dead bodies.
Image: Graphical Representation of Postmorem changes according to time
Death is a process caused in a systematic manner and this results in various changes in the dead body with respect to time. Different conditions around the dead body also helps in rapid or late decomposition of body. The cause of death also varies the time of decomposition.
The postmortem changes are the key for determination of time of death or postmortem interval, which is a very crucial aspect of death investigation. It can help the approximate time of death of a person and may reveal the cause of death.