Postmortem Changes- Late changes

 

Late changes

Putrefaction
It usually follows disappearance of rigor mortis. It results from breakdown of complex organic com­pounds into simpler forms by the action of bacteria, fungi, and protozoa etc.
Autolysis is an aseptic process where organic compounds are broken by the enzymes of the body.
The agent commonly respon­sible is Cl. welchii that causes hemolysis, liquefaction of postmortem clot, emboli, thrombi, breakdown of tissues and gas formation.
Imme­diately after death, there is breakdown of cell mem­branes and they also become permeable.
The fall in oxygen concentration and rise of hydrogen favors bacterial growth and their spread. Bacteria liberate several enzymes, one such enzyme is lecithinase liberated by Cl. Welchii that hydro­lyses the lecithin, which is present in all cell mem­branes including the red blood cells. This enzyme is responsible for postmortem haemo­lysis of blood. During the process of putrefaction, the soft parts of the body are affected first, and the bones are affected much later.
The greenish discoloration of the abdomen over right iliac fossa is due to the presence of caecum that lies super­ficially and close to the abdominal wall. The contents of the caecum are more fluid and full of bacteria that is why it deve­lops putrefaction at the earliest. Greenish discoloration is due to the change in the blood pigment and because of formation of sulphmeth­haemoglobin which is formed by the action of hydrogen sulfide on methaemoglobin. The color appears in 12 to 18 hours in summer and 18 to 24 hours in winter.
Catabolic putrefying process starts with normal microbial flora of skin and mucous membrane. Proteins breakdown to amino acids, deaminated or decarboxylated to acids or amines respectively
 
 
Greenish discoloration around lower chest and abdomen
 
There is formation of blebs and blisters between 18-24 hours due to putrefaction because gases in blood vessels may force bloodstained fluid, air and liquid in between epidermis and dermis. These blebs and blisters gradually enlarge and rupture causing peeling of epidermis exposing underlying dermis. External body appears distended and bloated due to formation of gases in tissue cavities and hollow viscera from 18-36 hours after death. Due to excessive pressure of gases in the abdomen the diaphragm moves upwards compressing the lungs and heart. As a result of which blood-stained froth will come out of mouth and nostrils known as postmortem purge. It can be mistaken for bleeding following ante mortem injuries. The marbling of skin occurs due to haemolysis and decomposition of blood in the superficial veins of neck and chest that stains the vessel walls. The marbling of skin occurs in 24 to 36 hours in summer and 36 to 48 hours in winter.
The maggots appear in 1-2 days, and they have proteolytic enzyme activity which penetrates the skin. After 3 days face becomes bloated, and identity becomes difficult. Hair and nail become loose and in 3-5 days the skin shows slippage. The offensive odor emitting out of a dead is due to formation of hydrogen sulfide gas and Mer­captans.
 
 

Distension of abdomen due to gases and formation of postmortem blebs and blisters  
                    Marbling due to decomposition



Peeling of epidermis and swollen genitals as a result accumulation of gases due to decomposition

 

Differences between ante mortem and postmortem blisters

Ante mortem blisters

Postmortem blisters

Line of redness is present

Not present

Contain serous fluid with albumin and chloride

Contain air only

Base of blister is inflamed

Base is dry and hard

Infection, pus, and sloughing is present

Not present

 
Colliquative putrefaction: Colliquative putre­faction is conversion of soft parts into a thick semifluid black mass. Walls of abdomen become soft and burst open as a result the sto­mach and intestine comes out. In the final stage of putrefaction, cartilage and ligaments are softened and the bones are destroyed.
Putrefaction of internal organs: The viscera become softened and greasy.
 (i) Larynx and tra­chea: their mucous mem­brane becomes softened and colour changes to brownish red and later gree­nish.
 (ii) Stomach and intestine: they show dark red to brownish patches first on the posterior wall and then on the anterior wall.
 (iii) Liver: liver softens and becomes flabby in 12 to 24 hours in summer. Blisters appear on its surface in 24 to 36 hours. The liver assumes a honeycomb” or “foamy” appea­­rance due to formation of air bubbles.
 (iv) Brain is greyish paste like due to decomposition.
 (v) Prostate: it resists putre­­faction for a very long time and this is the last organ to putrefy in males.
 (vi) Uterus: Uterus is the last organ to putrefy in females.
 
Greyish paste like brain material due to decomposition
Medico legal Aspects: (i) Late sign of death (ii) It helps in calculating time since death (iii) It helps in identification as hair, teeth and bones resist putrefaction.
Casper’s Dictum: The body putrefies twice as rapidly when taken out of water and eight times faster when taken out of grave and placed in air. These differences in rate of putrefaction are given by Casper as: Air: Water: Grave = 1:2:8.
 

Changes after death (Estimation of Postmortem interval or time since death)

Within 1 hour of death

Warm body with moist transparent cornea, General muscular flaccidity, Cessation of circulation and fragmentation of the blood columns in the retinal vessels

Within 2 hours

Body surface is cool to touch; Postmortem lividity is developing in the dependent parts and in patches by 1-2 hours. Cornea becomes hazy and intraocular pressure falls to zero. Rigor mortis will appear in the eye muscles and at times in jaw muscles.

Within 3-6 hours

Tache noires on the surface of sclerae, well developed hypostasis by 4-6 hours. Cornea becomes cloudy by 6 hours.

Between 6-12 hours

Eyeballs get shrunken into the orbits, well-marked hypostasis and it is fixed by 6-8 hours, Rigor mortis is well developed.

Between 12-24 hours

Rigor mortis will be in the phase of disappearance. Greenish patch of discoloration is seen in right iliac fossa by 12-18 hours in summers and in 24-36 hours it extends over chest, trunk, and abdomen. Foul smelling gases may emit from the body. Eyeballs can bulge out; face is swollen, and abdomen is distended.

Between 24 -48 hours

Rigor mortis passes off in summer within 20-24 hours and in winters it may continue up to 36 to 48 hours. Marbling of skin and body features is bloated, tongue is protruded out, and postmortem blisters will form over different body parts. Immature and mature maggots appear.

Between 48-72 hours

Hair and nails become loose, prolapse of rectum or uterus.

Between 3-5 days

Skull sutures separate, brain gets liquefied, Nails, hair, tooth become loose and may fall off. Bones become loose at their respective joints.

Between 5-10 days

Colliquative necrosis. Soft tissues get changed into black mass separating from bony attachments

Beyond 10 days -1 to 2 months

Soft tissues including cartilage has fallen off and only detached skeletal parts are left out and skeletonization is likely to occur in 1-2 months.

Skeletonization: In an uncoffined buried body, it takes about one year for skeletonization. In airtight coffins the decaying of body is delayed for several decades.
 
Adipocere adipo: (fat) and cere (wax)
Adipocere formation replaces the putrefaction changes when the body remains submerged in water for apprecia­ble time, buried in moist graves or water-logged soil.  Soft, waxy looking substance, Greasy to touch, Dull white to deep brown in colour, Disagreeable rancid odour, inflammable and burns with faint yellow flame. Gradual hydrolysis and hydro­genation of preexisting fat like olein that is con­verted to higher fatty acids like palmitic acid, stearic acid, hydroxystearic acid, glycerides etc. Hard waxy character is due to hydroxystearic acid, calcium soaps and proteins that occur as inci­dental components.
Certain bacterial enzymes liberated from decom­­­­­po­sing protein are necessary for the hydro­genation of unsaturated body fats in to satu­rated firmer fats. Water is essential for the change as it takes part in the synthesis and remo­ves glycerin formed during hydrolysis of fat. Moist conditions are necessary for adipocere formation though it has been seen in dry conditions also. It occurs rapidly in bodies submerged in water. In obese persons and mature new borne it is formed quickly. The adipocere formation is accelerated by heat and retarded by cold. In India it has been reported between 3-35 days.
Medico legal aspects: (i) Late sign of death (ii) Identification of individual is possible (iii) Nature of wounds and cause of wounds can be found out (iv) Time since death can be calculated.
 
                             Adipocere
Mummification
It is a modified form of putrefaction and is char­acterized by drying or shriveling of the tissue that is due to dehydration of the body constituents. When climate is dry and warm with a free circu­lation of air around the dead body, the putrefaction is inhibited.
It begins in the exposed parts of the body like face, hands etc. and then spread to other parts. The skin har­dens, becomes leathery and adheres to the bones.
The external appearance in a mummified body is preserved thus helping in identification. As the wounds remain intact, the cause of death can be determined. Inter­nal organ thickens and becomes deep brown.
The average time it takes is from few months to 1 year.
Medico legal aspects: (i) Late sign of death (ii) Identification of individual is possible (iii) Nature of wounds and cause of wounds can be found out (iv) Time since death can be calculated.
 
 
                           Mummification

#postmortem changes #rigormortis #pmlividity #hypostasis #adipocere #mummification

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