POST-MORTEM

CHANGES Part2

Hypostasis/Livor Mortis

Hypostasis/Livor Mortis(lividity or suggilation)

after death occurs, circulation of blood ceases & subsequent movement of blood is by gravity

blood accumulates in the capillaries in the dependent parts of the body purple or reddish purple discoloration of the adjacent skin

in pressure areas such as the shoulder blades, buttock & calves discoloration will be pale.

starts immediately after death. apparent after 2 hrs and fixed after 8 hrs. may not appear at all especially in infants, old

ppl and anemic ppl.

Hypostasis (cont’d)

early hrs after death it appears in the form of blotchy post-mortem hypostasis which usually sinks down and becomes confluent on the most dependant area

once hypostasis is established, there is controversy about its ability to undergo subsequent gravitational shift if the body is moved into a different posture.

Primary hypostasis may either: Remain fixed Move completely to the newly dependant zone Be partly fixed and partly relocated

Sites of Hypostasis

  Depends on the position of the body before death: Supine:

shoulders, buttocks heels pressing against surface give white color (pale).

Vertical (hanging): distally in legs & feet.

Drowning: chest, upper chest, and upper limbs.

Face-down death: as in epilepsy, drunken victims whitening around nose & lips.

Hypostasis may also occur in viscera: Heart: mistaken for MI Lungs: mistaken for pneumonia Intestine: mistaken for hemorrhagic infarction

Distribution of Hypostasis

If the body remains vertical after death as in hanging cases, hypostasis will be most marked in the feet and to a lesser extent the hands.

Color of Hypostasis

The color of hypostasis is variable and depends on the state of oxygenation at death. Usual color is blue-pink

It’s a crude indicator of the mode of death: Cherry-pink: CO poisoning Dark blue-pink: cyanide poisoning Brown: methahemoglobinemia Bronze: septic abortion caused by Clostridium

perfringes. Pallor: anemia, hemorrhage (or normal in extremes

of age)

Timing and Permanence of Hypostasis

Hypostasis appears at variable times after death May appear half hr to many hrs after death

In the early hrs after death it appears in the form of blotchy post-mortem hypostasis which usually sinks down and become confluent on the most dependant area.

Hypostasis vs. Bruises (Ecchymosis)Hypostasis Bruises

Dependant areas Any where

Well defined edges Ill defined edgesBlood is retained in

intact capillariesBlood escapes through

ruptured capillariesSuperficial Deep into skin

Same level on surface RaisedPale over pressure

areasRed

Incision: blood flows from the cut vessel

(washable)

Incision: blood coagulates in tissue

No swelling May be with swelling With a bruise, blood will not flow from the cut

Medico-legal Importance of Hypostasis

Sure sign of death Cause of death Time estimation Position before/ after death Indicate if the body was moved or not after

death

Body Cooling/ Algor Mortis

the most useful indicator of time of death during the first 24 hours post-mortem.

after death all metabolic activity ceases rapidly (muscles, liver) & circulation stops heat production ceases soon after death

The body surface begins cooling immediately after death, followed by delay in deep organs cooling, until a heat gradient is set up between the core of the body and the surface. Delay “temperature plateau” Plateau = variable: from minutes to 2-3 hours.

In practice the temperature is either measured per rectum or intra-hepatic via an abdominal stab.

The rate of body cooling: 1C/hr in summer 1.5C/hr in winter.

 

Factors affecting Rate of Cooling

 Surface area of the body: larger surface area speeds up cooling rate. Children: increase surface area gives rapid heat loss.

Body weight: Larger bw: slower cooling Smaller bw: faster cooling

Edema: slower cooling rate.

Clothing, posture and emaciation. Environmental Temperature :

Higher humidity: rapid cooling rate Rapid air velocity: rapid cooling rate

Water: rapid cooling rate: More rapid in flowing water than still water

If there is a fulminating infection, e.g. septicaemia, the body temperature may continue to rise for some hours after death.

POST-MORTEM DECOMPOSITION

Post-Mortem Decomposition

1. Putrefaction2. Mummification3. Adipocrere4. Skeletelization

Putrefaction

the normal final sign of death. starts immediately after death at the cellular level becomes visible in 48-72 hrs. its onset may be sped up or delayed by several factors

mainly: temperature humidity.

Two phenomena for putrefaction: Autolysis: occurs by digestive enzymes released from the

cells after death. Bacterial action: most of them come from the bowel and

Clostridium welchii predominates (same bacteria that causes gas gangrene)

The 1st visible sign of putrefaction is green or greenish red discoloration of the skin of the anterior abdominal wall normally starts in the right iliac fossa.

The next phase: gas formation blisters containing red fluid appear on the skin, mistaken as bleeding

Humidity, temperature, bacterial activity body proteins break into polypeptides & amino acids

Brain &epithelial tissues are the 1st to be affected by putrefaction

Heart, uterus & prostate may survive for longer periods.

Military plaques: nodules in heart (epi/endocardial) Marbling: bacteria colonize venous system hemolysis stain.

Marbling

Influences on Putrefaction A high environmental humidity will enhance

putrefaction. The rate of putrefaction is influenced by the bodily

habits of the decedent; obese individuals putrefy more rapidly than those who are lean.

Putrefaction will be delayed in deaths from exsanguination (bleeding to death) because blood provides a channel for the spread of putrefactive organisms within the body. Conversely, putrefaction is more rapid in persons

dying with widespread infection, congestive cardiac failure or retention of sodium and salts.

It tends to be more rapid in children than in adults, but the onset is relatively slow in unfed new-born infants because of the lack of commensal bacteria.

Influences on Putrefaction

Heavy clothing and other coverings, by retaining body heat, will speed up putrefaction.

Rapid putrefactive changes may been seen in corpses left in a room which is well heated, or in a bed with an electric blanket.

Injuries to the body surface promote putrefaction by providing portals of entry for bacteria and the associated blood provides an excellent medium for bacterial growth.