Post mortem Changes-final......................pptx

Post mortem Changes-finaL

1. Post Mortem Changes

2. Post Mortem Changes Can be divided into early and late changes distinguish them from ante mortem injuries May help to determine the time of death (post mortem interval) May help to establish position of body if subsequently moved

3. Peri mortem Changes Muscles rapidly become flaccid , may show focal twitching for a few hours Loss of sphincter tone , void urine (not restricted to asphyxia and epilepsy) Emission of semen may occur and does not necessarily indicate sexual activity Regurgitation very common, especially with resuscitation Gastric contents in mouth and upper airway not necessarily aspiration

4. Early Postmortem Changes

5. Early Changes 1. Rigor mortis 2. Livor mortis (post mortem hypostasis) 3. Algor mortis (post mortem cooling) Only the last of these has any real utility in establishing the post mortem interval

6. Stiffening of muscles postmortem due to chemical changes in the mycoplasm begins after death but, detected hours after death stiffness progresses with time maximum between 8-12hrs postmortem at room temp 1. Rigor mortis

7. First detectable in small muscles of face, jaw and fingers Spreads down from head to involve bulkier muscles of leg Develops faster if involved in vigorous exercise at the moment of death, also electrocution Develops slowly, if at all in elderly and frail

8. Estimation of PMI by Rigor Body warm and flaccid = dead < 3 hr Body warm and stiff = dead 3-8 hr Body cold and stiff = dead 8 – 36 hr Body cold and flaccid = dead > 36 hr

9. Factors influencing Rigor Cold environment , onset of rigor delayed and duration prolonged Warm environment , onset of rigor more rapid and shorter duration Infection, terminal seizures or hyperactivity, electrocution, increased body temp, increased environmental temp= all hasten onset of rigor mortis NB: Test rigor gently, once “broken” and muscle group cannot be re-tested

10. 2. Livor mortis (Post mortem Hypostasis) Passive settling of red cells under force of gravity once circulation stops Purple-red discolouration in dependent areas Blanching from contact with surface or clothing May be absent in anaemia, blood loss May be masked by dark skin or jaundice May indicate that body has been moved

11. begins when heart stops beating intensity increases with time fully developed in 10-12hrs fixed, no blanching with pressure different patterns of livor in same body= body has been moved

12. Special forms of Hypostasis Carbon monoxide poisoning : cherry pink/red Cyanide poisoning : brick red Hypothermia : prominent around large joints and bony prominences

13. Internal lividity lungs other organs

14. 3. Algor mortis (Post Mortem Cooling) Temperature should fall according to Newton’s Law of cooling rate of heat loss of a body is directly proportional to the difference in the temperatures between the body and its surroundings

15. Assumption; that body is uniform that body temperature was 37 C that environment has remained at a constant temperature

16. Factors influencing Cooling Body mass Mass: Surface area ratio Body posture Clothing Weather, wind, rain, humidity

17. Estimation of Time of Death Body temperature Gastric contents / emptying Biochemical methods Entomology

18. Late Post Mortem Changes

19. Late Post Mortem Changes Putrefaction , liquefaction of soft tissues, stages of marbling, blistering and gaseous distension Mummification , dessication Adipocere , saponification of fat with water exposure Skeletalisation , after approximately two years in soil

20. Putrefactive decomposition result of postmortem bacterial proliferation with gas formation gas= bloating of tissues externally and internally Skin slippage

21. rate of PM change and decomposition

22. Marbling branching pattern ? results from denaturation of blood within vessel

23. Marbling branching pattern ? results from denaturation of blood within vessel

24. Mummification occurs under dry conditions (warm or cool) skin- firm, leathery tough, yellow brown to black

25. Adipocere under moist conditions adipose tissue of body undergoes a chemical change to become adipocere (gray waxy substances) can be hard and brittle usu 3months to develop

26. Casper’s Law Decomposition is slowed by immersion in water or burial 1 week in air = 2 weeks in water =8 weeks in earth

27. End