Practical Pathology of Gunshot Wounds

Archives of Pathology & Laboratory Medicine, Sep 2006 by Denton, J Scott, Segovia, Adrienne, Filkins, James A

* Context.-Gunshot wounds are the most common cause of homicidal death in the United States. Analysis and interpretation of fatal gunshot wounds is an important and common practice among forensic pathologists. Additionally, for pathology residents, it is an integral aspect of their training during their rotations at medical examiner or coroner offices.

Objective.-The correct interpretation of gunshot wounds by forensic pathologists not only provides valuable information that can assist law enforcement in their investigation but also is essential for the final determination of manner of death. Discussion of the practical, basic, and essential skills required to interpret gunshot wounds include distinguishing a classic entrance wound from an exit wound; recognizing atypical entrance and exit wounds; utilizing the features of soot and stippling patterns to differentiate among contact, close, and distant range gunshot wounds; understanding of the trauma produced by gunshot wounds; and understanding the importance of recovering and documenting/handling any projectiles recovered at autopsy.

Data Sources.-This article reviews numerous standard forensic pathology textbooks and the pertinent literature to formulate practical guidelines to assist the pathologist in the performance of forensic autopsies and the investigation of gunshot wound fatalities.

Conclusions.-Pathologists who perform investigations and autopsies to determine the cause and manner of death in gunshot wound cases must be aware of the implications, requirements, and pitfalls in interpretation of the injuries so that the examination fulfills its expectations to the community and the justice system.

(Arch Pathol Lab Med. 2006;130:1283-1289)

Gunshot wounds are the most common cause of homicide in the United States and, in many jurisdictions, the most common means of suicide. It is estimated that each year in United States there are approximately 70 000 victims of gunshot wounds, with 30 000 deaths.1 The medical, legal, and emotional costs of this violence impose a staggering burden on urban trauma hospitals, court systems, families, and society in general. The evaluation of these wounds requires specialized training and expertise, whether by an emergency physician in a living gunshot victim or a forensic pathologist in the deceased.

When a person dies from a gunshot wound, the investigation of the death falls to the local medicolegal death investigation system. In a large urban setting this is usually a medical examiner's office, headed by a chief medical examiner and staffed by forensic pathologists who have completed specialized postresidency fellowship training. In other jurisdictions, the responsibility belongs to the elected coroner and his or her designated forensic pathologist. Distinguishing among accidental, suicidal, and homicidal gunshot wounds; estimating range of firing; and distinguishing exit wounds from entrance wounds are critical skills and just a few of the reasons why a forensic pathologist must be an expert in interpreting gunshot injuries. An error in any of these determinations can have far-reaching consequences for the family of the deceased, the accused, the legal system, and the forensic pathologist. This article seeks to lay basic groundwork for understanding the pathology of gunshot wounds.

GUNS AND AMMUNITION

A forensic pathologist does not have to be a weapons expert to interpret gunshot pathology correctly, but, because bullets fired from handguns and rifles produce gunshot wounds, a forensic pathologist should at least be familiar with the nomenclature and operation of commonly used guns and ammunition. The examination and interpretation of firearms and bullets is termed ballistics or firearms examination. It is a separate field of expertise from forensic pathology requiring specialized training and instruments of its own.2 The basic functional unit of a modern round of ammunition is the cartridge.3 A cartridge consists of a cartridge casing, a primer, and a projectile or bullet. The cartridge casing contains the propellant or gunpowder. The primer is located at the base of the cartridge casing. The bullet is tightly fitted into the opposite end of the cartridge casing. When the gun's firing pin strikes the primer, a small explosive charge in the primer ignites the gunpowder. Rapidly expanding gases produced by the combustion of the gunpowder propel the bullet out of the cartridge casing and down the barrel of the gun. As the bullet accelerates down the barrel, rifling from twisted slots within the barrel rotate the bullet causing it to spin along its axis, maintaining a straighter, more accurate trajectory. Each gun has a unique pattern of rifling, which produces a corresponding pattern of ridges and grooves around the base of the bullet as it travels down the barrel. It is this pattern of ridges and grooves surrounding the base of a bullet that often enables a ballistics expert to match the bullet to the weapon that fired it. For this reason, it is an important rule of forensic pathology that nobody is buried with a retained bullet, either from an old or new gunshot injury. All bullets are recovered and saved.