What is an autopsy? |

The Fundamentals of Pathology

Translated literally, pathology is the study (logos) of suffering (pathos). As a science, pathology focuses on the study of the structural and functional consequences of injury on cells, tissues, and organs and ultimately the consequences on the entire organism (that is, the patient). Oftentimes, cells and fragments of tissues are obtained surgically from living patients; this procedure, called biopsy
, is for the purpose of evaluating the nature and extent of injury. The results of a biopsy help direct the treatment. Autopsy, by contrast, is performed to examine the dead body and the internal organs systematically, in order to determine why the patient died.

Four aspects of a disease process form the core of pathology and are searched for diligently during autopsy studies. These are etiology, or cause; pathogenesis, the mechanism of development of disease; morphologic changes, the structural alterations induced in cells, tissues, and organs of the body; and clinical significance, the functional consequences of these morphologic changes.

There are two major classes of etiologic causation factors: genetic and acquired. Examples of acquired factors are infections, physical trauma, chemical injury and poisoning, nutritional factors, and radiation and solar injury (sunburn). When an autopsy is performed, this etiology is sought, but it has been acknowledged that the classic concept of one cause leading to one disease—developed largely from the discovery of specific infectious agents as the causes of specific diseases—is no longer sufficient. More often than not, multiple factors are acting at once. Genetic factors also affect environmentally induced diseases: for example, not all alcoholic patients develop significant liver disease (cirrhosis). Conversely, environment may have a profound influence on genetically induced disease: for example, not all individuals with the chemical and genetic markers for gout will develop that disease. During autopsies, systematic samplings of blood, body fluids, and tissues are taken in order to test for microbial causes and often chemical causes.

Pathogenesis refers to the sequence of events in the cells and organs that results from injury, from the initial responses to the ultimate expression of disease. It has become clear, for example, that many events at the subcellular and molecular levels are interacting and taking shape long before a disease becomes clinically observable. For example, the virus that causes acquired immunodeficiency syndrome (AIDS) destroys lymphocytes (special white blood cells) and causes a gradual loss of immunity in the body long before AIDS becomes clinically observable as a disease.

Morphologic changes are the structural and associated functional alterations in cells, tissues, and organs that are characteristic of a disease process. They are directly observed at the autopsy table by “gross” or “macroscopic” inspection of the body and organs and later by “microscopic” or histologic study of tissue samples removed from these organs. These morphologic studies can be carried out in extreme detail using the electron microscope (ultrastructural studies) and immunologic or even genetic and molecular analysis. In forensic medicine, deoxyribonucleic acid (DNA) evidence is at times used as a definitive “thumbprint” of specific genetic makeup and can be obtained from even a few hairs.

The nature of these morphologic changes and their distribution in different organs influence normal function and determine the observed clinical features—the signs and symptoms of disease, such as fever and pain—and the disease’s course and outcome. Thus, the clinical significance of these alterations can be used to assess the cause of death.

Procedures and Techniques

Autopsies are performed for several generally recognized purposes, which are closely related. Medical autopsies are performed to improve the diagnosis of disease and to help the practicing or treating physician avoid repeating errors in diagnosis and therapy; it has been repeatedly shown that autopsies contribute to improvements in medical care. The College of American Pathologists has stressed the importance and necessity of the autopsy as a service to both the medical community and the public, recognizing it as a useful medical procedure performed by a qualified physician to assess the quality of patient care and evaluate clinical diagnostic accuracy. The autopsy is also a valuable tool for determining the effectiveness and impact of treatment modalities, discovering and defining new and/or changing diseases (as in AIDS), increasing the understanding of biological processes of disease (pathogenesis), and augmenting clinical and basic research. Information gathered from autopsies is used to provide accurate public health and vital statistical information and education as it relates to disease. Finally, the autopsy is used for obtaining legal, factual information.

In the United States, permission to perform an autopsy must be granted. A legal action can arise when the autopsy consent has not been obtained or when it has not been obtained from the proper person. The statutes of individual states usually establish who can consent to the autopsy. In general, a surviving spouse has first priority for authorizing an autopsy, and in the absence of the spouse, the next of kin has legal custody of the body and the right to authorize an autopsy. Some statutes indicate that whoever assumes custody of the body for burial may give permission for autopsy.

At large medical centers, there usually is an autopsy service, the director of which is a qualified anatomic pathologist. At times, there is also a perinatal pathologist, an anatomic pathologist specializing in the pathology of newly born babies. House officers who are medical doctors-in-training often assist in performing the autopsies. The autopsy suite is a well-equipped theater usually in close proximity to the morgue and is served by a diener.

Thus, the usual autopsy is performed by professional pathologists. After carefully examining the body as a whole and recording its various attributes, the pathologist makes a surgical incision to allow for the detailed inspection of the body cavities and the organ systems, looking for gross abnormalities. Every organ is thus examined, measured, and weighed and its description recorded. Sampled sections of the organs are then taken for histologic studies, and samples of blood and other body contents may be taken for microbiologic and chemical studies.

The objectives of the autopsy will vary among institutions and even among cases within an institution. For example, an academic institution with a training program in pathology, a private hospital without a training program, and a medical examiner’s office might be expected to approach a specific autopsy with very different objectives. Nevertheless, a minimum basic and standard level of examination, description, and tissue sampling is usually done. Photography is also used to document the gross findings.

Histologic study of the tissue samples is completed, and the results of microbiologic and chemical analysis are obtained. After the patient’s record is carefully reviewed and all the findings are correlated, often in consultation with the decedent’s treating physician, a final document, the autopsy report, is produced.

In many autopsies, the basic gross, histologic, chemical, and microscopic examination will be inadequate to resolve fully all questions raised by the circumstances of the patient’s clinical course and death. The ability to carry out additional studies may then become critical to resolving these questions. Ancillary studies to which pathologists may resort include injections of substances into blood vessels to observe blockages (angiography), chromosomal studies, toxicology, x-ray defractions, and histochemical procedures. The results of these studies are also recorded in the final autopsy report.

Two standard techniques are generally used to perform autopsies. They differ from each other in the order in which the organs are removed and in whether single organs or intact organ systems are removed from the body. In Virchow’s technique, organs are removed one by one. Originally, the first step was to expose the cranial cavity, the spinal cord, and the thoracic, cervical, and abdominal organs, in that order. This technique, with some modifications, is still widely used. In Rokitansky’s technique, the dissection is initially carried out in situ (before the removal) and then combined with en bloc removal. This technique is often modified when used in medical centers, where the en bloc removal of the cervical, thoracic, and abdominal organs is done. Dissection of the various organ systems is performed after removal.

Another technique, Potter’s technique, is often used in pediatric autopsies. The external examination, particularly of fetuses and newborns, concentrates on the search for congenital malformations; the face, ears, or hands may reveal characteristic symptoms of a disorder, such as with Down syndrome. The placenta and umbilical cord must be studied in all autopsies for fetuses and newborns. Less invasive autopsy procedures for infants are being developed and put into practice, including MRI scans.

Few autopsies offer more difficulties than postoperative cases, in which death has occurred during or shortly after a surgical operation. The pathologist must evaluate his or her findings in the light of their medicolegal implications, such as complications from surgical intervention, anesthesia, or drug administration. At times, obtaining permission to conduct an autopsy may require certain restrictions in its performance. In such restricted autopsies, access can be confined to only the chest
or abdomen, or to the reopening of surgical wounds.

Medicolegal autopsies are best carried out by forensic pathologists, who must first ascertain that death has, in fact, occurred. (Failure to do so has, on occasion, led to embarrassment and serious repercussions.) Not all medicolegal autopsies deal with violent or unnatural deaths. Generally, more than half of all cases investigated by the office of the chief medical examiner in New York are deaths from natural causes that occur suddenly, unexpectedly, or in an unusual manner. Coronary heart disease (heart attacks) and respiratory infections (pneumonias) are the most common causes of death in such cases, and the greatest incidence is in persons forty-five to fifty-five years of age. Strenuous physical or emotional activity may bring about a heart attack in a patient with undetected but severe narrowing of the coronary vessels.

When a crime is suspected, evaluation of the circumstances of death and investigation of the scene where the body was found may be crucial. The position of the body, the distribution of the blood lost by the victim or the assailant, or objects found in the vicinity may offer important clues. Identification of the body can be a complex issue, especially with mutilated or decomposed bodies, and may involve x-ray and dental studies, as well as detailed studies of body contents and hair samples.

Estimation of the time of death is another concern of the forensic pathologist; at times, this can be determined very simply by the circumstantial evidence. For example, when, after a rainy night, the ground under the body is found to be dry, death probably occurred before the onset of rain. More often, however, the time of death is estimated from physical or chemical measurements of values whose rate of postmortem change has been found to be rather constant, such as body temperature or the chemical analysis of certain body and blood constituents. These methods can be useful for short postmortem intervals. For longer intervals, a determination of the level of potassium in the vitreous humor (a gelatinous fluid in the eyeball) is fairly reliable.

Special procedures are used by the forensic pathologist to investigate questions related to criminal abortion, vehicular and aircraft accidents, air embolism, decompression sickness, drowning, exposure to elements, gunshot wounds, rape, and infanticide (in which the main objective is to decide whether the infant was born alive or was a stillbirth).

Toxicologic autopsies, in which poisoning is suspected, are also the responsibility of the forensic pathologist. The sampling of tissues, especially from the brain, liver, lung, kidneys, fat, hair, fingernails, and stomach contents, is done, and samples are also collected from urine, blood, bile, and the vitreous humor of the eyeball. The list of possible poisons and drugs that can be abused is endless, and the investigation of which poison may be the cause of death is both an art and a science.

Perspective and Prospects

The field of pathology is, next to therapeutics (the study of medicinal substances), the oldest division of the healing arts because it is the study of disease itself. Its historical development can be broadly sketched in five different periods, each one highlighted by a fundamental change in the concept of the “seat of disease.” An examination of the steps by which pathology has reached its present state provides a useful perspective on the subject.

At the dawn of history, primitive humans believed that there was only a single disease, one that could produce disturbances as varied as headaches, blood vomit, epilepsy, or the death of mother and child during labor. While, in some of those cases, there were apparent causes of death, the real causes were thought to be hidden and supernatural. Thus, the concept of disease was not localized to any specific organ or even to a war wound or broken bone.

The idea of “humors” soon took over. It began in ancient Egypt, was well articulated by the Greeks, and came to dominate medical thought in the Western world up to the Renaissance. The humoral theory of disease proposes that illness is the result of disturbance in the equilibrium between four qualities (hot, cold, wet, and dry) and four elements (air, water, fire, and earth) to affect four body constituents (blood, yellow bile, black bile, and phlegm). This theory was championed by such intellectual giants as Aristotle, Pythagoras, and even Hippocrates and was fine-tuned by Galen in the second century.

The theory of the “equilibrium of humors” implies that disease affects not the entire organism but only such fluids, or humors, indicated by the specific disease. Thus a man has jaundice because of an imbalance of his humors caused by an excess of yellow bile, an excess resulting from the winds blowing in the wrong direction. One disease had become many diseases, with specific seats within the body, but these seats were not subject to anatomic evaluation.

The study of anatomy and gross pathology (that is, autopsy) became generalized in the sixteenth century, and it sounded the death knell for humoral pathology. Antonio Benivieni (1443–1502) is rightfully considered the founder of gross pathology. He is the first physician who performed autopsies, and his medical text appears to be the first to deal with anatomic and gross changes in different organs in relation to clinical symptoms. He worked in the same hospital in Florence, Italy, where the great anatomist Leonardo da Vinci conducted his anatomic dissections. His book contains the protocols for fifteen autopsies performed to ascertain the cause of death, or the seat of disease. Also of great significance in this period is the work of Jean-François Fernel (1497–1558), from Paris, whose book Medicina (1554) was divided into three parts: physiology, pathology, and therapeutics. The section on pathology contains 120 chapters and separates diseases into special groups, with brief autopsy presentations for clinical correlation.

The seventeenth century saw the emergence of a small group of physicians who collected the accounts of all available experiences and published them in enormous volumes. Théophile Bonet (1620–89) is the most important of these reviewers, and his book, Corps de medecine et de chirurgie (1679), appearing about two hundred years after Benivieni’s, contains summaries of more than three thousand autopsy protocols, including those of Benivieni himself and other masters such as Andreas Vesalius. This book was the stimulus for the monumental contribution of Giovanni Battista Morgagni (1682–1771), whose work marks the official inauguration of anatomic pathology and autopsy as a science. His classic text, De sedibus et causis morborum per anatomen indagatis (1761), contains the clinical histories and autopsy protocols of more than seven hundred cases, correlating the morphologic and clinical findings. More important, he committed his autopsy studies to the revelation of the cause of disease, thus establishing the general principle that “seats of disease” are internal body organs, not humors, and that localization in different organs explains different symptoms. This concept served as the basis for the fundamental work of anatomic pathologists-clinicians such as René-Théophile-Hyacinthe Laënnec and Richard Bright.

The next great step in the development of pathology, and establishing the premiership of autopsy as its medium of study, was the French pathologist Marie-François-Xavier Bichat (1771–1802), who established in Recherches physiologiques sur la vie et la mort (1800) that organs are formed of elements called tissues. The work of Rudolf Virchow (1821–1902) raised pathology to the premier medical science; he placed the concept of the microscopic cell as the unit of life at the center of medicine and his theory of cellular pathology, thus making cells the unit and “seat” of disease.

Impressive strides in subcellular and molecular pathology have established many morphologic lesions within subcellular structures, even within genes. Such studies can be performed on minute samples of tissues obtained through fine probes. These biopsy techniques and the great technological advances in nuclear and radiologic investigative techniques have allowed the physician to study the cause and extent of disease during the patient’s lifetime and with a high level of sophistication. Thus, the role of the autopsy has declined somewhat as an educational tool, but the practice continues to be used in clinical research, medical statistics, public health, and population genetics and to procure organs for tissue transplantation. In fact, many of the functions of autopsy will be extended and improved. For example, the demand for transplantable tissues and organs, procured from cadavers, is likely to increase. Also, recognition of new diseases will occur, aided by postmortem examinations and the application of new technologies and ancillary studies. The autopsy still has much to contribute to education and research, as it constitutes a priceless, continuing, and intimate contact with the natural history of
disease.

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