Forensic pathology, which for practical purposes deals with the
postmortem investigation of sudden and unexpected death, is about as
far from the mainstream of medicine as one can get, short of actually
becoming Surgeon General or a medical school dean. The training of a
forensic pathologist generally entails a complete five-year residency
in anatomic and clinical pathology, followed by one or more years of
fellowship training in a medical examiner's office in a large city
"fortunate" enough to have hundreds of homicides per year. A completely
credentialed forensic pathologist is certified by the American Board of
Pathology as both a general pathologist and as a subspecialist,
following successful completion of the Board examinations in anatomic,
clinical, and forensic pathology. For information on how to become a
forensic pathologist, see Forensic
Pathology Careers: Frequently-Asked Questions.
The good forensic pathologist is an amalgamation of pathologist,
detective, politician, and public relations person. Not only must one
know the technical aspect of the discipline, but he/she needs to have
the communication skills to acquire supportive information from law
enforcement officers and explain the results of medical examinations to
juries (which are specifically selected for technical ignorance) and
other laypeople. Also, mediocre media operatives, desperate for
exposees when news is slow, find medical examiners to be quick and easy
targets. Forensic pathology, because it involves no mean amount of
educated guessing, lends itself well to glib Monday morning
quarterbacking by amateurs.
[There are a few peculiar incidental advantages to being in the
world of forensic pathology. 1) In many jurisdictions, the forensic
pathologist, as a criminal investigator, may acquire a permit to carry
a handgun. This is perfect for those just macho enough to wish to go
armed, but not so macho as to want to go to jail for it. 2) Since
forensic pathologists typically work in nonmedical institutions, such
as city morgues and county medical examiner's offices, they may be
exempt from licensing/certifying agencies and may thumb their noses at
even the most basic laboratory safety practices. It is something of a
tradition for a lot of eating and smoking to be going on while actually
performing autopsies. On the other hand, forensic pathologists are not
known for their longevity]
II. Role of the Forensic Pathologist
Forensic determinations go beyond those of patient-oriented
medicine, as they involve legal as well as medical considerations:
A. Cause of death
This is a specific medical diagnosis denoting a disease or injury
(e.g., myocardial infarction, strangulation, gunshot wound). In
1. Proximate cause of death. The initial injury
that led to a sequence of events which caused the death of the victim.
2. Immediate cause of death. The injury or
disease that finally killed the individual.
Example: A man burned extensively as a result of a house
fire dies two weeks later due to sepsis. The proximate cause of death
is his burns, leading to sepsis, which is the immediate cause of death.
B. Mechanism of death
This term describes the altered physiology by which a disease or
injury produces death (e.g., arrhythmia, hypoventilatory hypoxia,
C. Manner of death
This determination deals with the legal implications superimposed on
biological cause and mechanism of death:
1. Homicide. Someone else caused the victim's
death, whether by intention (robber shoots convenience store clerk) or
by criminal negligence (drunk driver, going 55 mph on Fondren, runs red
light at Bellaire and strikes pedestrians in crosswalk). After the
forensic determination is made, it may of course be altered as a result
of a grand jury or other legal inquiry. For instance, when one child
shoots another, the forensic examination may conclude from the body
that homicide was the manner of death, but after considering all
evidence, a grand jury may conclude that the gun discharged
2. Suicide. The victim caused his/her own death
on purpose. This may not always be straightforward. For instance, a
victim may strangle himself accidentally during autoerotic behavior
(apparently some people find a certain amount of hypoxia very
stimulating). If the examiner were not to consider all of the evidence
(such as erotic literature found near the body), an incorrect
determination of "suicide by hanging" might be made. This error may be
financially disastrous for the victim's survivors, since many life
insurance policies do not award benefits when the insured is a suicide.
Also, in some cultures suicide is a social stigma or a sin against its
3. Accidental. In this manner of death, the
individual falls victim to a hostile environment. Some degree of human
negligence may be involved in accidental deaths, but the magnitude of
the negligence falls short of that reasonably expected in negligent
homicide. Whereas the negligence of the speeding drunk, above, would be
considered gross by a reasonable observer, a pedestrian killed at the
same intersection by a sober driver, not speeding or running a red
light, would be reasonably considered a victim of accidental death.
4. Natural causes. Here, the victim dies in the
absence of an environment reasonably considered hostile to human life.
Most bodies referred for forensic examination represent this manner of
death. We will consider the major diseases producing sudden death
III. "Normal" postmortem changes
These are important to be familiar with, as they may otherwise
mislead the examiner into thinking trauma or other foul play led to the
A. Rigor mortis, familiar to any aficionado of
horror films, begins earlier in small muscles and muscles exercised
vigorously prior to death. An extreme example is "cadaveric spasm," a
great literary/cinematic device, in which a person dying following
extreme exertion "freezes" in place virtually in a photographic pose of
the moment of death. I would imagine that this occurs a lot more often
in movies than in reality. Rigor mortis passes as muscle decomposition
begins and is usually gone in 36 hours. It can also be mechanically
"broken" by stretching the rigid muscles by force.
B. Livor mortis, or hypostasis, a purplish
discoloration of the body and organ surfaces, results when blood
settles to dependent parts of the body. It becomes visible between
onehalf hour and two hours after death. Early on, the blood remains in
the vessels, so the livor can be blanched by applying pressure to the
affected part. Later, the blood hemolyzes, and the hemoglobin breakdown
pigment leaches out into the extravascular interstitium. At this point,
the livor cannot be blanched by pressure and is said to be "fixed." The
period over which livor becomes fixed is so variable that whether it is
fixed or not offers little information in trying to determine the time
C. Desiccation occurs most prominently on the
mucous membranes, which during life are kept moist (by blinking, lip
licking, etc) and are not protective by water repellant keratin in
cornified skin. The membranes may look "burned," and the conjunctiva
may actually be black ("tache noire").
D. Putrefaction is the sequence of
physicochemical events that begins with death and ends with dissolution
of the nondurable parts of the body. It begins with a greenish
discoloration of the skin and mucous membranes. The epidermis becomes
detached from its basement membrane, and flaccid cutaneous bullae form.
Overgrowth of bacteria (which normally seed the entire body via the
bloodstream at or immediately before the time of death) cause gas
production, resulting in gaseous distension of the body cavities, which
may then rupture. The soft tissues may also puff up and appear swollen,
also as a result of gas release. Finally, autolysis and bacterial lysis
hydrolyze proteins and fats, to produce frank liquefaction of the soft
tissues. The proteins get broken down into amino acids, which then are
decarboxylated and become "biogenic amines" with such memorable and apt
names as "putrescene" and "cadaverine." Other protein-derived products
of putrefaction are amino acid residues with sulfhydryl (-SH) groups;
these are also mighty rank. The sulfhydryl groups are often further
cleaved off, then released as hydrogen sulfide, which also has the
ability to put your olfactory neurons into overload.
E. Alternatives to putrefaction include
mummification, in which the body dries out faster than
decomposition takes place, and adipocere formation, in
which by some unknown mechanism the adipose tissues become chemically
transformed into a waxy substance that acts as a preservative. As might
be expected, mummification typically occurs in dry environments.
Adipocere formation, which is much rarer, tends to occur in moist
environments, such as caves. A good example of adipocere can be viewed
at Philadelphia's Mutter Museum, where the "Soap Lady" is on exhibit.
This is the cornerstone of forensic pathology. Terms used to
describe traumatic lesions are somewhat more specific than analogous
terms used in surgery and internal medicine.
A. Laceration is a tearing injury due to
friction or impact with a blunt object. The typical laceration has
edges which are ragged3, bruised, and/or abraded. Generally, surgeons
and ER physicians do not make a distinction between lacerations and
incised wounds, calling them both "lacerations."
B. Incised wound is a cutting injury due to
slicing action of a bladelike object. The wound edges are smooth.
Serrated blades produce the same smooth edges as do nonserrated blades.
C. Puncture is a penetrating injury due to
pointed object without a blade, such as an ice pick.
D. Abrasion is a friction injury removing
superficial layers of skin, allowing serum to exude and form a crust.
Abrasions may not be visible on wet skin; therefore, an abrasion not
apparent when a body is first examined may appear the next day, after
the wet body has had a chance to dry out in the morgue refrigerator.
E. Contusion is a bruise due to rupture or
penetration of small-caliber blood vessel walls. Contusions may be seen
on the surfaces of internal organs (such as the brain or heart) as well
as the skin and mucous membranes.
F. Gunshot wounds represent a special form of
trauma very important to forensic pathology. The types of
determinations made on bodies include 1) type of firearm used (shotgun,
handgun/rifle, or high-powered rifle), 2) distance of the gun from the
victim at the time of firing, 3) whether a given wound is an entrance
wound or an exit wound, and 4) track of the projectile through the
body. Wounds may be classified by distance as follows:
1. Contact wound: Muzzle of gun was applied to
skin at time of shooting. Classic features include an impression of the
muzzle burned around the entrance wound and absence of fouling and
stippling (see below). Contact wounds over the skull may have a
stellate appearance because of expulsion of hot gases from the barrel
which are trapped against the outer table of the skull and blow back
toward the exterior, ripping apart the skin around the entrance wound.
2. Close range (6 - 8 inches): The entrance
wound is surrounded by fouling, which is soot that travels for a short
distance from the gun barrel to be depositied on the skin. There may
also be stippling (see below).
3. Intermediate range ( 6 - 8 inches to 1.5 - 3.5
feet): This is too far for soot to travel, so there is no
fouling, but hot fragments of burning propellant (gunpowder) follow the
bullet to the victim and produce stippling by causing pinpoint burns
around the entrance wound. Of the two type of propellant, "ball" and
"flake," the former will produce stippling at a greater distance.
4. Distant (greater than 1.5 - 3.5 feet): This
is too far for either soot or burning propellant to travel, so the
wound margins are clean, with neither fouling nor stippling. Entrance
versus exit wounds represents an important distinction for the forensic
pathologist to make. A grand jury may look with more favor on an
assailant alleging self defense, if the victim has the entrance wound
on the front and the exit wound on the back, rather than vice versa.
Classically, the entrance wound has a rim of abrasion surrounding the
wound, because the projectile "drags" the surrounding skin into the
wound a bit, abrading it along the way. The exit wound lacks this
abrasion, unless the victim was braced against a wall or other solid
object that may secondarily abrade the margin of the exit wound as the
projectile penetrates the skin and pushes it into the wall.
V. Death by Natural Causes
Perhaps having a bit more relevance to patient-oriented medicine is
the problem of sudden and unexplained death by natural causes. Careful
attention to the autopsy and the patient's history usually establish
the cause of death, but a few cases, like that of Elvis Presley, will
remain mysteries indefinitely.
A. Coronary artery disease is the most common
cause of nontraumatic sudden death. Autopsy typically shows occlusion
of at least 60% of the luminal cross-section of one or more of the
three major branches of the coronary arterial system. The occlusion may
be all atheroma, or thrombus superimposed on atheroma. It is likely
that spasm of the coronary artery, which cannot be demonstrated at
autopsy, plays a rúle in a significant proportion of these cases. The
myocardium itself may be perfectly normal, death having resulted from
ischemia-induced arrhythmia before anatomic changes of infarction have
time to develop.
B. Pulmonary embolus, typically a saddle
thromboembolus, stops the heart by some type of reflex action. At
autopsy all that may be found is the embolus itself, as the patient
dies before anatomic changes of pulmonary infarction have time to
develop. Emboli may occur in previously normal individuals, but one may
find in some cases a history of recent immobilization (like a truck
driver on a long haul, or a person recently discharged from the
C. Myocarditis, typically of viral etiology,
may cause sudden death, often in association with vigorous physical
activity. There may be history of a recent acute viral upper
D. Aortic valvular stenosis physiologically
resembles coronary artery disease in a patient with essential
hypertension. The coronary ostia are poorly supplied due to the marked
pressure differential across the aortic valve. Also, the myocardium
demands more blood supply as a result of having to pump against that
pressure gradient. Most cases nowadays are due to a congenital bicuspid
aortic valve, but a history of old rheumatic fever should be sought.
E. Berry aneurysms of the arteries at the base
of the brain may rupture, producing fatal subarachnoid hemorrhage. The
typical victim is a young or middle-aged female. There may be history
of complaints of a very severe headache immediately before the
F. Intracerebral hemorrhage is usually seen in
older, typically hypertensive patients. Embolic or atherosclerotic
strokes usually do not produce sudden death
G. Perforated peptic ulcer is common, as about
10% of peptic ulcers present with perforation and no previously
documented manifestations. Fortunately, only rarely do they produce
sudden death. The mechanism of death is unknown but probably involves
some sort of autonomic reflex (which is what is typically invoked when
the cognoscenti have absolutely no idea about what the pathogenetic
H. Anaphylaxis, better known as Type I
Immunologic Hypersensitivity Reaction From Hell, may cause sudden death
by laryngeal edema, causing asphyxiation. Usually, the inciting
stimulus (bee sting, penicillin injection, etc.) is apparent from the
This article is provided "as is" without any express or implied
While every effort has been taken to ensure the accuracy of the
information, the author assumes no responsibility for errors or
omissions, or for damages resulting from use of the information herein.
Copyright (c) 1995, Edward O. Uthman. This material
may be reformatted and/or freely distributed via online services or
other media, as long as it is not substantively altered. Authors,
educators, and others are welcome to use any ideas presented herein,
but I would ask for acknowledgment in any published work derived
therefrom. Commercial use is not allowed without the prior written
consent of the author.