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POST-MORTEM CHANGES Part2 Rashed Dawabsheh 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: Vertical (hanging): chest, upper chest, and upper limbs. Face-down death: distally in legs & feet. Drowning: shoulders, buttocks heels pressing against surface give white color (pale). 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 Dependant areas Bruises Any where Well defined edges Blood is retained in intact capillaries Superficial Same level on surface Pale over pressure areas Incision: blood flows from the cut vessel (washable) No swelling Ill defined edges Blood escapes through ruptured capillaries Deep into skin Raised Red Incision: blood coagulates in tissue 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 postmortem. 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. 2. 3. 4. Putrefaction Mummification Adipocrere 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 The next phase: normally starts in the right iliac fossa. 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.
