Decomposition involves two processes: autolysis and putrefaction. Autolysis is the breakdown of cells and organs through an aseptic chemical process caused by intracellular enzymes. Since it is a chemical process, it is accelerated by heat, slowed by cold, and stopped by freezing or the inactivation of enzymes by heat. Organs rich in enzymes will undergo autolysis faster than organs with lesser amounts of enzyme. Thus, the pancreas autolyzes before the heart.
The second form of decomposition, which to most individuals is synonymous with decomposition, is putrefaction. This is due to bacteria and fermentation. After death, the bacterial flora of the gastrointestinal tract spread throughout the body, producing putrefaction. This is accelerated in septic individuals because bacteria have already spread throughout the body prior to death.
When we talk about decomposition, we usually mean putrefaction. The onset of putrefaction depends on two main factors: the environment and the body. In hot climates, the more important of these two factors is environment.
Most authorities would give the following sequence of events in decomposition of bodies. First there is greenish discoloration of the lower quadrants of the abdomen, the right more than the left, usually in the first 24-36 h. This is followed by greenish discoloration of the head, neck, and shoulders; swelling of the face due to bacterial gas formation; and "marbling." Marbling is produced by hemolysis of blood in vessels with reaction of hemoglobin and hydrogen sulfide and development of greenish black coloration along the vessels (Figure 2.6). The body soon undergoes generalized bloating (60-72 h) followed by vesicle formation, skin slippage, and hair slippage. By this time, the body is a pale green to green-black color.
Figure 2.6 Marbling.
Bloating of the body is often noted first in the face, where the features are swollen, the eyes bulge, and the tongue protrudes between the teeth and lips. The face has a pale greenish color, changing to greenish black, then to black (Figure 2.7A). Decomposition fluid (purge fluid) will drain from the
mouth and nose (Figure 2.8). This is often misinterpreted by the inexperienced as blood, and head trauma is suspected. Decomposition fluid will accumulate in body cavities and should not be confused with hemothorax
in the case of the pleural cavities. Usually, the fluid accumulating in each pleural cavity is less than 200 mL.
As decomposition continues, hemolyzed blood leaks out into the tissue. Especially in the scalp, this cannot readily be differentiated from antemortem bruising. Thus, in the dependent areas of the head in decomposed bodies, one must be very cautious in interpreting blood in the tissue as a contusion.
This description of the gradual decomposition of a body assumes a temperate environmental climate. With high temperature, this process can be accelerated. Thus, in Texas, a body left in a car during the summer will take less than 24 h to go from a fresh state to a swollen, greenish-black body with marbling, vesicle formation, skin slippage, and purge fluid.
Cold weather slows down and may even stop decomposition. A frozen body will not undergo decomposition until it defrosts. Extreme examples of this are mammoths frozen in Siberia for thousands of years.
Decomposition is hastened by obesity, heavy clothing, and sepsis, all of which keep the body warm. Decomposition is delayed by tight clothing or by the body's lying on a metallic or stone surface that will rapidly cool it by conduction. In the case of generalized sepsis, the authors have seen bodies undergo accelerated decomposition in spite of the fact that they were immediately refrigerated. A septic body dead 6-12 h may have the appearance of one dead 5-6 days even if refrigerated.
Even in the non-septic body, if decomposition has set in, immediate refrigeration of the body may not necessarily stop decomposition completely (Figure 2.7A, B). Thus, the authors have seen a number of bodies in which there was early decomposition with opaque eyes, a reddish tinge to the skin of the face, and bloody purge fluid in the mouth and nostrils when the body was initially viewed at the scene. When the body came to autopsy 6-12 h later, after having been refrigerated the whole time, the face was bloated and greenish black.
As decomposition progresses, hair slips off the head and skin from the hands. Thus, one finds "gloves" of skin. Hair may be taken by birds in the area and used to build nests. As the body decomposes and swells, one often gets the impression of a very heavy individual. When the body is actually weighed, however, the weight will be found to be significantly less than estimated on gross examination of the body. As decomposition proceeds, the weight of the organs decreases.
In hot, dry climates, the body can dehydrate rapidly and may go into mummification rather than decomposition. While the skin will have a brown to black leathery appearance, the internal organs will continue to deteriorate, often reduced to a blackish-brown putty-like consistency.
Bodies are embalmed to delay decomposition. The success of embalming is variable and depends on the quality of the embalming, the climate, and the nature of the ground where the body is buried. Rarely will a body be perfectly preserved for years. One of the authors disinterred the body of an elderly white female buried for 6 years that was in perfect condition and could have been "viewed" at a funeral. There was no odor, no observable changes to the outside of the body, and no fungus present. Microscopic sections from the embalmed organs were perfectly preserved. The body of another female buried the same length of time, but in ground where water leaked into the coffin, was completely skeletonized. The authors have seen bodies buried for a year perfectly preserved, except for some drying of the fingertips and patches of fungus, while other bodies buried 2-3 weeks are in an advanced state of decomposition.
The time necessary for skeletonization of a body is also variable. In areas where the body is exposed to the elements and scavengers, it can proceed quite rapidly, occurring in 9-10 days. In rare instances, it may be even faster than this. The uterus and prostate are two of the last organs to decompose.
Occasionally, a decomposing body will undergo transformation to adi-pocere (Figure 2.9). Adipocere is a firm, greyish-white to brown wax-like material composed of oleic, palmitic, and stearic acids. It is produced by conversion of neutral fats during putrefaction to the aforementioned acids. It is most prominent in subcutaneous tissue, but can occur wherever fat is present. Adipocere is really a variation of putrefaction. It is seen most
Figure 2.9 Adipocere.
commonly in bodies immersed in water or in damp, warm environments. In adipocere, fat undergoes hydrolysis to free fatty acids by virtue of endogenous lipases and bacterial enzymes. Bacterial enzymes, principally from Clostridium perfringens, convert these free fatty acids to hydroxy fatty acids.4 Adipocere is said to take several months to develop, though development can be as short as several weeks. It is relatively resistant to both bacteriologic and chemical degradation.
A brief mention should be made of maceration of infants in intrauterine deaths. This is not truly putrefaction, but rather an aseptic autolytic process. It is described in a separate section.
Eye changes postmortem are difficult to interpret. Changes depends on whether the eyes are open or closed and on the environment. Tache noire is seen, but often not observed. It is an artifact of drying consisting of a brown to black band of discolored sclera where the eyes are partly open and exposed to the air (Figure 2.10). In closed eyes, by 24 h, there is usually a white scummy deposit on the cornea, which, in turn, is cloudy.
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