LATE POSTMORTEM CHANGES/DECOMPOSITION

WILLIAM A. COX, M.D.

FORENSIC PATHOLOGIST/NEUROPATHOLOGIST

November 17, 2009

General Information

The process of postmortem decomposition can be divided into five stages: Fresh (autolysis), putrefaction, black putrefaction, butyric fermentation and dry decay. The first stage begins within minutes of death and last typically up to 36 to 72 hours before the beginning of putrefaction. The length of this first stage, as is true of the entire decomposition process, is primarily determined by environmental temperature. The higher the temperature the faster the decomposition process proceeds through each of the stages. The first stage of decomposition was discussed in the previous article on early postmortem decomposition. This stage included rigor mortis, livor mortis and algor mortis. The underlying process, which initiates the first stage, is autolysis.

Autolysis is the result of molecular changes occurring within the cell, which gives rise to the death of the cell and its subsequent necrosis. This process gives rise to the release of enzymes from the cells, such as the pancreas, and in the case of the stomach also hydrochloric acid.

The pancreas, because of the richness of its enzyme content, provides for digestion of food by secreting more than a liter of digestive juice/24 hours into the digestive tract. Within the digestive juice are enzymes (e.g., amylase, lipase) and precursor enzymes (e.g., trypsinogen), which are responsible for the breakdown of ingested food. Unfortunately, these same enzymes are released from the exocrine cells of the pancreas into itself, which gives rise to autodigestion (autolysis).

The stomach contains a variety of cells, which secrete enzymes and hydrochloric acid that participates in digestion. One of the cells of the stomach are Chief cells, which produce an enzyme pepsinogen. Another cell is the Parietal cell, which, in addition to producing intrinsic factor needed for the intestinal absorption of vitamin B12, also produces hydrochloric acid. Following death both pepsinogen and hydrochloric acid are released from these cells, which gives rise to autodigestion of the gastric mucosa (gastromalacia). If this process is severe enough it can cause perforation of the stomach, typically in the region of the fundus. This same process can also involve the distal ? pf the esophagus due to relaxation of the lower esophageal sphincter following death. This allows for the gastric contents containing the described enzymes and hydrochloric acid to pass into the lumen of the distal esophagus-giving rise to autodigestion (esophagomalacia) of its mucosa and on occasion perforation of its wall. Both gastromalacia and esophagomalacia can give rise to stomach contents leaking into the abdominal cavity and left pleural cavity respectfully. Both can occur within a few hours of death. Although, gastromalacia and esophagomalacia are not common postmortem features, they are seen most frequently in those who have sustained substantive intracranial injuries or have developed terminal pyrexias. These complications have been attributed to an imbalance in the activity of the autonomic nervous system, possibly as a consequence of hypothalamic or brain stem injury.

When the cells of the body reach the end of the autolytic process, an anaerobic environment is created one in which oxygen is no longer present. At this point the body’s normal bacteria begin to break down the tissues further producing acids, gases, and volatile organic compounds with their putrefactive effects.

Putrefaction

Putrefaction is the process by which tissue is destroyed primarily through bacterial proliferation, which occurs soon after death. The bacteria most responsible are those normally found in the respiratory tract and gastrointestinal tract. These bacteria include anaerobic spore forming bacilli, coliform organisms, micrococci, diphtheroids and proteus organisms. The growth of these anaerobic organisms is enhanced due to the increase in hydrogen-ion concentration in the tissues as well as the immediate decrease in oxygen concentration. Between the respiratory and gastrointestinal tracts, it is the latter, which provides the majority of postmortem bacterial growth of which Clostridium welchii is the principal agent. The principal factor, which influences this process, is environmental temperature. Should the deceased have been pyretic prior to death that will also have an effect on the rapidity of development of putrefaction. The optimal temperature for the development of putrefaction is between 70 – 100 ?F. Putrefaction is retarded below a temperature of 50 ?F and is hasten by temperature above 100 ?F.

Putrefaction also occurs faster in those who are obese, have septicemia, congestive heart failure or anasarca, have multiple layers of clothing, hot and humid environments, those dying of cocaine intoxication and those who have sustained traumatic lacerations or incised wounds to the body. Although, warm temperatures hasten putrefaction, very high temperatures will actually delay putrefaction, primarily due to the drying effect on the tissues.

Putrefaction will proceed at a slower rate in cooler temperatures, with freezing suspending the process all-together, in those who are thin, in infants, those who are found in water, those who die in a dry environment, whether cold or warm, those who are found lying on a stone surface and in some cases in which the person has been buried.

In reference to those who have been buried, whether putrefaction is hasten or delayed will be determined by the depth of burial, temperature of the soil, water table, the natural drainage of the burial site and the quality of construction and water tightness of the coffin. If the decedent is buried deep, in well drained soil, especially clay soil, whose coffin is water tight, the process of putrefaction will be substantively delayed. If however, the gravesite is shallow, the soil is moist with poor drainage or the water table is high and the coffin is not water tight the rate of putrefaction will be hastened. However, even without embalming a body buried in a sufficiently dry environment may be well preserved for decades. It is generally agreed that an unembalmed adult buried deep in well drained soil, with a water tight coffin, will be reduce to a skeleton in approximately 10 years, whereas a child will become a skeleton in approximately 5 years. There is a general axiom referred to as “Casper’s dictum” which provides an overall perspective to the putrefaction process, “one week of putrefaction in air is equivalent to two weeks in water, which is equivalent to 8 weeks buried in soil, given the same environmental temperatures.”

The first evidence of putrefaction is the development of a greenish discoloration to the skin usually in the lower right abdominal quadrant, although occasionally you may see it develop simultaneously or initially in the peri-umbilical or left lower abdominal regions. This is typically seen between 36 to 72 hours following death at a temperature of approximately 70 ?F. The green discoloration is due to the spread of bacteria from the cecum, which lies close to the overlying peritoneal lining in the right lower abdominal quadrant, into the soft tissues. It then spreads from the right lower abdominal quadrant to the remaining abdominal wall followed by involvement of the flanks, chest, limbs and face. The actual green color is due to the bacteria breaking down the hemoglobin of red blood cells (R.B.C) along with the concomitant production of hydrogen sulfide, the net effect of which is sulfhemoglobin. During this process the superficial veins of the skin become visible in an arboressent pattern delineated by a purple-brown coloration. This process is referred to as marblization, which is most commonly seen on the superior aspect of the chest, shoulders, arms and lateral aspect of the trunk. On occasion you may see marblization on the anterior-medial aspect of the thighs. This process is due to the anaerobic bacteria spreading through the veins participating in the hemolysis of the R.B.C., which leads to the staining pattern of marblization, the color being due to hemolyzed R.B.C. reacting with hydrogen sulfide produced by the bacteria. The hemolysis of the R.B.C. will also impart a red color to the endothelial lining of the arteries as well as the endocardium. The time frame that marblization occurs in again is very much temperature dependent. Typically in temperate climates, if the body is exposed to air at temperatures between 64 and 68 ?F, marblization may appear with in thirty-six to forty-eight hours. It will develop much more rapidly in warmer temperatures.

At this point the skin has taken on a slippery feel and is showing multiple vesicles to frank blisters filled with serous fluid and putrid gases. These vesicles and blisters culminate into skin slippage, with areas of the skin being easily removed from the body with minimal contact. The skin slippage represents the superficial epidermis. The underlying base has a shinny, moist, pink appearance, which if the body is located in a warm dry environment takes on an orange-yellow parchment-like appearance. Along with skin slippage the hair of the scalp, axillae and pubic region is easily removed with minimal pressure.

The skin about the face, neck, upper chest and arms begins to change from a red-green to gray-green, followed by brown-green to purple black color. Gradually this coloration will involve the entire body, however, not necessarily with the same intensity. The entire body will show putrefactive changes in about sixty to seventy-two hours. The change in coloration from green to more of a brown to black hue represents the transition from the early stage of putrefaction to the advanced stage, which is referred to as black putrefaction.

Black Putrefaction

The abdomen at this point is bulging and tense due to putrid gas formation from primarily coliform bacteria and Clostridium welchii both within the gastrointestinal tract and within the abdominal cavity, organs and soft tissues of the chest and abdominal cavities. The putrid gas formation with its concomitant increase in intra abdominal and gastrointestinal luminal pressure leads to purging of putrid, blood-stained fluid from the nose, mouth, vagina and rectum. This same putrid gas formation within the tissue leads to bloating of the body (swelling) in general. The purple-black face swells which also includes swelling of the eyelids and lips, which gives rise to the eyelids being tightly closed and the lips taking on a “fish-mouth-like appearance.” The swollen tongue, often having a purple-black color is seen protruding between the swollen lips. The teeth will often show a red discoloration due to the diffusion of hemoglobin from the lysed R.B.C. into the dentin canaliculi. The swelling of the face and neck can approach grotesqueness, which along with the purple-black color can make identification impossible. The scrotum and penis in the male and the labia majora and breast in the female also exhibit prominent swelling. The gases, which are responsible for this bloating, are comprised of hydrogen sulphide, methane, carbon dioxide, ammonia and hydrogen. These gases, along with the produced mercaptans are responsible for the disagreeable odor these bodies produce.

Typically generalized bloating with purging, skull and hair slippage at a temperature of 70 ?F occurs between 60 - 72 hours. In addition to the head and body hair becoming loose at their roots and thus being easily removed by minimal pressure, the finger and toenails will at some point become dislodged. Sometime the dislodged finger and toenails will contain much of the epidermis (superficial layer of skin) of the hands and feet, a process called ‘degloving.’ This process of ‘degloving’ occurs at a later time than the loss of either scalp or body hair.

Just as putrefaction affects the external surface of the body so does it involve the internal organs. The stomach and small and large bowel begin to dilate due to various gases being produced by the bacteria within these structures. Both the serosal and mucosal surfaces assume a brown-deep red to purple color. The normal rugal folds become flat. The mucosa of the larynx, trachea and especially the bronchial tree take on a deep-red color; the lumen of the bronchial tree often contains thin reddish-black fluid. The endothelial lining of the major vessels as well as the endocardial surface of the heart has a reddish hue due to hemolysis of R.B.C., thus releasing hemoglobin, which stains these surfaces. On a rare occasion you may see white granules measuring approximately 1 mm in diameter on the surface of the epicardium as well as the endocardium. These white granules are referred to as ‘miliary plaques’ and are believed to be the result of a degenerative process of the cardiac muscle. These ‘miliary plaques’ are rich in calcium. The heart becomes soft and flabby, giving rise to dilatation of the cardiac chambers and thinning of the chamber walls. They myocardium takes on a deep red-brown color. Although, these postmortem decomposition changes make diagnosing antemortem dilated cardiomyopathy virtually impossible, thrombi within the epicardial coronary arteries can still be ascertained. Thus, it is important you dissect the coronary vasculature.

The liver and kidneys assume a deep reddish-brown color with the parenchyma of both organs losing consistency, most especially the liver. As the decomposition process continues the liver shows a myriad of minute cysts, which develops into a honeycomb pattern due to bacterial production of various gases. Bile within the gallbladder diffuses through the degenerating wall staining the adjacent liver, transverse colon and duodenum an olive green color. The adrenal glands quickly undergo autolysis, as does the pancreas. Decomposition fluid, which has a dirty-red color, accumulates in the pleural and abdominal cavities. The chest and abdominal wall panniculus as well as the perirenal, omental and mesenteric fat becomes very slippery, giving rise to a translucent yellow fluid, which also seeps into the body cavities. Organs such as the prostate and uterus remain well preserved even up to a point where the body is partially skeletal zed. The lungs take on a deep red-black color, losing their elasticity, becoming very friable. As they degenerate they exude a dirty red fluid into the pleural cavities.