Forensics chapter - Postmortem changes

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Forensics

Postmortem changes

Author: Lindsey Harle, M.D. (see Reviewers page)
Revised: 19 February 2012, last major update February 2012
Copyright: (c) 2012, PathologyOutlines.com, Inc.

Livor mortis
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● Also called lividity; pink to purple skin discoloration due to blood settling in dependent portions of the body
● Areas exposed to pressure will not show lividity, as the blood vessels are mechanically compressed preventing blood flow
● Begins to develop 1-3 hours after death and fully developed by 10 to 12 hours
● Initially, livor is due to blood settling within vessels, and thus can shift with movement of the body and will blanch with pressure
● Later, blood will hemolyze and diffuse out of the vascular space; at this point, livor is fixed; it will not shift with movement of the body and is nonblanchable
● As livor progresses, some bodies show dark purple Tardieu spots in dependent areas, due to ruptured capillaries
● Livor mortis can be differentiated from a true antemortem contusion by incising the skin – contusions will show extravascular hemorrhage in the subcutaneous tissue
● In carbon monoxide poisoning, livor is cherry red in color; prolonged refrigeration causes the same color change

Livor mortis

Tardieu spots

Rigor mortis
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● Stiffening of the body due to postmortem muscle contraction

Rigor mortis

● Occurs as ATP is depleted, preventing relaxation of muscle fibers
● Begins to develop several hours after death; rigor initially develops in the jaw, followed by upper and lower extremities
● Rigor is fully developed in approximately 6 to 12 hours
● Rigor dissipates due to decomposition in approximately 36-48 hours
● Infection, terminal seizure, electrocution, strenuous exercise or high body temperature may cause rigor to develop more rapidly
● In hot weather, rigor dissipates more rapidly; in cold weather, rigor may persist longer

Decomposition
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● Bodies decompose more rapidly in hot environments and slowly in cold environments
● Autolysis: aseptic breakdown of tissues due to the release of intracellular enzymes

Autolysis

● Putrefaction: breakdown of tissue due to bacteria
     ● Green discoloration of the lower abdomen, due to overgrowth of colonic bacteria
     ● Green-black discoloration and swelling of the face and neck
     ● Red-brown purge fluid may extrude from the nose and mouth; this should not be confused with blood
     ● Gas formation causes diffuse swelling of the body, most noticeable in the abdomen
     ● Skin slippage and blistering; hair slippage from the scalp
     ● Marbling occurs due to breakdown of hemoglobin within blood vessels
     ● Brain becomes partially liquefied
     ● Skeletonization: usually takes several weeks

Putrefaction

Marbling

Purge fluid

Skeletonization of head due to maggots

● Adipocere formation: transformation of body fat to oleic, palmitic, and stearic acids, appears yellow, white, or brown and waxy; rare, and occurs in humid or wet environments
● Mummification: skin turns yellow-brown or black, becomes dry and leathery; occurs in dry environments

Additional references
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● eMedicine, DiMaio V, Dana S. Handbook of Forensic Pathology (2nd edition), Taylor and Francis, 2007, Dolinak D, Matshes E, Lew E. Forensic Pathology: Principles and Practice, Elsevier, 2005

End of Forensics > Postmortem changes

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