Postmortem Changes Flashcards
What are the immediate changes?
Happens within few mins
Loss of brain func (earliest), then circulation, and respiration
What are the early changes?
Occurs within hours to days
Skin, eye changes
Algor mortis (cooling)
Livor mortis (staining)
Rigor mortis (rigidity)
What are the late changes?
Occurs within days to weeks
Putrefaction
Adipocere
Mummification
What are the skin changes?
Pallor
Loss of elasticity
What are the changes in muscle?
Primary flaccidity of muscle
Loss of muscle tone
Drooping of jaw
Relaxation of sphincter
What are the eye changes?
Few mins - railroad appearance of retinal vessels
3-6 hrs - tache noire sclerotica (triangle shaped opacities) & dust deposition (reddish brown) in sclera
1-6 hrs - corneal opacity
Flaccidity of eye ball
Dilation of pupil
Loss of corneal & pupillary reflexes
When does algor mortis occur?
15 minutes after death
Instrument used and sites that can be used measure temperature
Instrument - thanotometer
Sites - rectal, sub-hepatic, intra-tracheal, intranasal, middle ear cavity
Formula to calculate PM interval (hrs)
PM interval (hrs) = (normal body temperature - rectal temperature)/rate of temperature fall (hrs)
What is the usual rate of fall in temperature?
0.4-0.7 per hour
Factors affecting algor mortis
Location of the body
Naked/clothed
Weather/season
Environment (water/underground)
PM caloricity
Body remains warm for 1-2 hours, seen when body core temperature increases at time of death
Eg. Heat stroke, pontine hemorrhage, strychine poisoning, tetanus, septicemia and cholera
MLI of algor mortis
Time since death
What is livor mortis?
Bluish/purplish discoloration of skin after death due to settling down of blood in the toneless capillaries in the dependent portions of the body.
When does PM lividity appear?
Begins 1-2 hours after death (patches)
Completes by 4-6 hours
When does PM lividity get fixed?
Hemolysis & diffusion of pigments to skin by 6-8 hours
What is contact pallor?
Areas of tight contact -> compression of vessels leading to no PM staining
E.g tight clothing, at pressures points
Conditions where PM lividity will not develop
Tossing of body in flowing water
Severe anemia
Hemorrhagic/hypovolemic shock
Difference between PM lividity and bruise
PM - seen in the skin, on dependent parts, no swelling, uniform in color and on incision slight oozing blood seen which can be washed away
Bruise - seen under the skin anywhere, swelling maybe present, different colors and it extravasated blood
MLI for PM lividity
Sign of death
Time since death
Position of the body at the time of death
Whether body was moved
Cause of death
What is rigor mortis?
Stiffening of the body after death
3 phases - primary flaccidity, rigor mortis, secondary flaccidity
What is the pathophysiology of rigor mortis?
After death, ATP depletes
- rigor begins when ATP decreases to 85% of its storage
- rigor maximum when ATP decreases to 15% of its storage
Then actin myosin filaments are bound by dehydrated , stiff, gel-like mass causing the muscles to become rigid
Explain the rule of 12
Rigor mortis begins to appear 1-2 hours after death. Gets well established in 9-12 hours. Maintained in that state for 12 hours and then after another 12 hours it disappears.
Order of appearance & disappearance of rigor mortis
Starts appear/disappear from face, neck, trunk, arms and lower limbs
Appears/disappears earlier in involuntary muscles (heart within an hour)
Factors affecting rigor mortis
- Temperature
- Condition of muscles before death - exhaustion, convulsion, diseases
- Age factor
MLI of rigor mortis
Time since death
Position of the body at the time of death
Heat-stiffening
Heat exposure leading to protein coagulation causing body to stiffen
Cold stiffening
Body in cold chamber causing joint fluids to freezes leading to stiffness of body
Gas stiffening
Gas produced during decomposition leading to bloating and stiffness of body, protrusion of tongue and eyeball
Cadaveric spasm
Spasm of group of voluntary muscle in use at time of death; antemortem finding
Define decomposition
The final stage of dissolution of body tissues resulting in breaking down of complex organic body constituents into simpler inorganic ones
Autolysis, Putrefaction
What is autolysis?
Softening & liquefaction of tissues under sterile conditions
E.g IUD maceration of fetus
What is putrefaction?
Produced by action of microorganisms (bacterial enzymes) that acts on protein and fats
Blood being the medium for bacterial growth
What are the features of putrefaction?
Color changes
Evolution of gases
Liquefaction of tissues
Describe the color changes
1st external sign is the greenish discoloration of right iliac fossa seen within 12-24 hours (in summer) and 1-2 days (in winter)
Bacterial spread + hemoglobin forming derivatives of HB causing this greenish-black-sulphmethhaemoglobin
This spreads to abdomen, genitalia, chest, neck, face (purplish, greenish, greenish-black)
Within 36-48 hours, there will be marbled appearance of the skin
Describe the evolution of gases
12-24 hrs - gas accumulates in intestine
24-48 hrs - gas in tissues, cavities & hollow viscera
2-3 days - post mortem blister formation, skin slippage, uterus & anal prolapse
What are the features that gets bloated and distorted?
- Distension of face, genitalia and abdomen
- Eyes bulging, tongue forced out, swollen lips
- Diaphragm forced upwards (postmortem purge)
- Sphincter relax - urine & faeces may escape
Describe liquefaction of tissues that occurs in 3-7 days
- bursting open of abdomen & thorax
- degloving of skin of palm & sole
- teeth, hair & nails: loose & pulled put easily
Describe liquefaction of tissues that occurs from 5-10 days
Collequative necrosis
- soft tissues: thick, semi-solid, black masses
- separate from bones & falls off
- finally - cartilages & ligaments softens
When does skeletonization occurs?
1-3 months in open air
2-6 months if buried
More time if coffined
Earliest sign of putrefaction of internal organs
Reddish brown discoloration of inner surface of aorta & other vessels
Early putrefaction in which internal organs?
Larynx & trachea
Stomach & intestine
Spleen
Omentum & mesentery
Liver (foamy liver)
Brain
Gravid uterus
Late putrefaction in which internal organs?
Lungs
Heart
Kidneys
Oesophagus, diaphragm
Bladder
Blood vessels
Prostate & uterus
Factors influencing putrefaction
- Atmospheric temp - bacterial growth occurs in 70-100 F (20-40 C)
- Medium of disposal - Casper’s dictum (air:water:burial = 1:2:8)
- Cause of death
- Clothing on the body
What is adipocere?
Occurs within 3-6 months; can be 3-15 days in india
A modified form of putrefaction where hydrolysis and hydrogenation of pre-existing unsaturated fats occurs & converts into firmer saturated fatty acids
What are the pre-requisites for adipocere to occur?
- abundance of moisture
- hot & humid weather
- abundance of adipose tissue
- presence of bacteria (clostridium welchii)
Features of adipocere
Initially - soft, greasy, pale white
Later - dry, hard, yellowish, brittle
Rancid/sweetish odor
Inflammable
Floats in water, dissolves in alcohol/ether
What is mummification?
Occurs within 3 months - 1 year
A modified form of putrefaction where dehydration and desiccation of tissues occurs
What are the pre-requisites for mummification to occur?
- absence of moisture
- dry & warm climate
- free circulation of air
Describe the appearance of mummification
- shriveled, dry, leathery, parchmentised, stretched tightly across anatomical prominences
- practical odorless
- internal organs are shrunken, hard, brown-black as a single mass
MLI of adipocere & mummification
- Features are unaltered: can establish identity and cause of death
- time since death
What is forensic entomology?
Study of insect that infest dead bodies to aid legal investigations
There are 8 successive waves of invasion (beginning of putrefaction to skeletonization)
Types of insects that infest on dead bodies
Blowflies (calliphoridae) - bluebottle, greenbottle, black blowfly
Flesh fly (sacrophagidae) - infest open wounds
House fly (muscidae)
Beetle, mite, moth, bee, wasp
What is the life cycle of blowfly?
Laying egg - 18-36 hrs
Larvae (maggot) - 12-24 hrs
Pupae - 4-5 days
Young fly (nymph) - 4-5 days
MLI of forensic entomology
Time since death = A+Bx(cd)
- A = stage of invasion (hrs, days, wk, month)
- B = stage of life cycle (hrs, day)
- cd = climatic factor correction
Detection of poison
