Gunshot injuries can be accurately identified and classified as entrance, atypical entrance, exit, or atypical (grazing) wounds based upon their physical characteristics. Wounds are not classified based upon their size. Physical findings in and around these wounds may offer evidence as to the actual mechanism of injury, supporting or refuting the initial history given to the provider. As most physical findings are transient in nature (cleaned, debrided, or eventually healed), the emergency physician must be diligent in recognizing and documenting them at the time of presentation. The physician’s failure to accurately document the physical characteristics of the wounds or correctly interpret the physical findings can compromise the legal process and obstruct justice.
Gunshot wounds of entrance are divided into four categories based on their range of fire: distant, intermediate, close, and contact. Range-of-fire is the distance from the gun’s muzzle to the victim’s skin or clothing.
The size of the entrance wound bears no relation to the caliber of the inflicting bullet. Entrance wounds over elastic tissue will contract around the tissue defect and have a diameter much less than the caliber of the bullet.
Distant Wounds: The distant wound is inflicted from a range sufficiently distant that the bullet is the only component expelled from the muzzle that reaches the skin. There is no visible tattooing or soot deposition associated with a distant entrance wound. As the bullet penetrates the skin, friction between it and the epithelium results in the creation of an “abrasion collar” (Fig. 19.1). The width of the abrasion collar will vary with the angle of impact. Elongated abrasion collars from projectiles that enter on an angle may produce a collar with a “comet tail” (Fig. 19.2). Most entrance wounds will have an abrasion collar; however, gunshot wounds to the palms and soles are exceptions—their entrance wounds appear slit-like. Bullets that pass through an intermediate object, a door or windshield for example, will become deformed or misshapen (Fig. 19.3). A misshapen bullet creates an irregular abrasion collar (Fig. 19.4) as compared to the smooth abrasion collar created by a nondeformed bullet (Fig. 19.1).
Distant Gunshot Wound. An abrasion collar surrounds the wound defect and is created from the friction of a bullet passing through the skin. All entrance wounds will have an abrasion collar with the exception of entrance wounds to the palms and soles. The lack of soot, seared skin, or gunpowder tattooing confirms this is a “distant” range of fire. (Photo contributor: William S. Smock, MD.)
“Comet-Tailed” Abrasion Collar. The “comet tail” abrasion collar located on the lateral aspect of the wound indicates that the bullet entered the wound at an angle. The “comet tail” also indicates the bullet’s direction of travel: from left to right. (Photo contributor: William S. Smock, MD.)
Deformed Bullet. This bullet passed through a car windshield and deformed prior to striking the suspect in the arm. The bullet’s irregular shape created the atypical abrasion collar associated with the entrance wound seen in Fig. 19.4. (Photo contributor: William S. Smock, MD.)
Atypical Abrasion Collar. When a bullet passes through an intermediate object, ie, a door or windshield, it can become deformed or misshapen with an irregular surface. When a misshapen bullet (Fig. 19.3) passes through skin, the abrasion collar it generates appears irregular and jagged when compared to the smooth one caused by the nondeformed bullet (Figs. 19.1 and 19.2). (Photo contributor: William S. Smock, MD.)
Intermediate-Range Wounds: Tattooing is pathognomonic for an intermediate-range gunshot wound and presents as punctate abrasions from contact with partially burned or unburned grains of gunpowder (Fig. 19.5). This tattooing cannot be wiped away. Clothing and hair, as intermediate objects, may prevent the gunpowder grains from making contact with the skin. Tattooing can, but rarely does, occur on the palms and soles owing to the thickness of their epithelium.
Intermediate-Range Gunshot Wound. Punctate abrasions present on the skin are the result of impact from gunpowder that is either wholly or partially unburned. This phenomenon is termed tattooing or stippling. Tattooing is pathognomonic for intermediate-range (less than 48 inch) gunshot wounds. (Photo contributor: William S. Smock, MD.)
Tattooing has been reported with a range of fire as close as 1 cm and as far away as 4 feet. The density of the abrasions and the associated pattern will depend upon the barrel length, muzzle-to-skin distance, type of gunpowder (ball, flattened ball, or flake), presence of intermediate objects, and caliber of the weapon. Spherical powder travels farther and has greater penetration than flattened ball or flake powder. “Pseudotattooing” (Fig. 19.6) is punctate abrasions from fragments created when bullets pass through intermediate objects like wood or glass.
Pseudotattooing. Punctate abrasions present on the forearm are the result of impacts with glass fragments. The fragments were produced from bullets penetrating the windshield. (Photo contributor: William S. Smock, MD.)
Close-Range (Near-Contact) Wounds: “Close range” is defined as the maximum range at which soot is deposited on the clothing (Fig. 19.7) or wound (Fig. 19.8) and typically is a muzzle-to-victim distance of 6 inches or less. On rare occasions, however, soot has been found on victims as far as 12 inches from the offending weapon. The concentration of soot will vary inversely with the muzzle-to-victim distance and its appearance will be affected by the type of gunpowder and ammunition used, the barrel length, the caliber, and the type of weapon.
Soot and Bullet Wipe. Soot is the carbonaceous residue from the burning of gunpowder. Soot is associated with close-range wounds, 6 inches or less. Bullet wipe is residue and/or lead from the surface of the bullet that is transferred to clothing or skin. Bullet wipe can be seen at any range of fire. Clothing should be collected and packaged in separate paper bags for submission to the crime laboratory. (Photo contributor: William S. Smock, MD.)
Close-Range Gunshot Wound. The deposition of carbonaceous material or soot is seen on the palm from a close-range or near-contact gunshot wound. Soot is short-lived evidence and its presence surrounding a wound should always be documented. (Photo contributor: William S. Smock, MD.)
Contact Wounds: A contact wound occurs when the barrel or muzzle is in contact with the skin or clothing as the weapon is discharged. Contact wounds can be described as tight, where the muzzle is pushed hard against the skin, or loose, where the muzzle is incompletely or loosely in contact with the skin or clothing. Wounds sustained from tight contact with the barrel can vary in appearance from a small hole with seared, blackened edges (from the discharge of hot gases and an actual flame), to a gaping, stellate wound (from the expansion of the skin from gases) (Figs. 19.9 and 19.10). Large stellate wounds are often misinterpreted as exit wounds based solely upon their size and without adequate examination of the wound characteristics.
Contact Gunshot Wound with Muzzle Abrasion. A contact gunshot wound to the right temple from a 9 mm semiautomatic handgun. Note the triangle-shaped tears, soot, seared wound margins and a muzzle-abrasion at the 2-o’clock position. The muzzle abrasion or muzzle imprint was the result of the injection of gases into the skin, causing a rapid and forceful expansion of the skin against the barrel. (Photo contributor: William S. Smock, MD.)
Contact Gunshot Wound. A contact wound to the forehead from a .38 caliber handgun. The wound margins display triangle-shaped tears, searing, and soot deposition. (Photo contributor: William S. Smock, MD.)
In a tight-contact wound, all materials—the bullet, gases, soot, incompletely combusted gunpowder, and metal fragments—are driven into the wound. If the wound overlies thin or bony tissue, the hot gases will cause the skin to expand to such an extent that it stretches and tears. These tears will have a triangular shape, with the base of the tear overlying the entrance wound. Larger tears are associated with ammunition of .32 caliber or greater, or magnum loads.
Stellate tears are not pathognomonic for contact wounds. Tangential wounds, ricochet or tumbling bullets, and some exit wounds may also be stellate in appearance. These wounds are distinguished from tight-contact wounds by the absence of soot and powder within the wound. In some tight-contact wounds, expanding skin is forced back against the muzzle of the gun, causing a characteristic pattern contusion called a muzzle contusion (Fig. 19.9). An outline of the barrel can also be imprinted on the overlying clothing and is associated with contact wounds through clothing (Fig. 19.11). These patterns are helpful in determining the type of weapon (revolver or semiautomatic) used to inflict the injury and should be documented prior to wound debridement or surgery.
Muzzle Imprint, Soot, and Seared Fibers. The clothing exhibits a “horseshoe-shaped” soot mark reflecting the outline of the frame of a semiautomatic handgun. Seared fibers are the result of flame and hot gases expelled from the barrel when it is in contact with clothing. (Photo contributor: William S. Smock, MD.)
With a loose-contact wound, where the muzzle is angled or held loosely against the skin, soot and gunpowder residue will be present in and around the wound. The angle between the muzzle and skin will determine the soot pattern. A perpendicular, loose-contact or near-contact injury results in searing of the skin and deposition of the soot evenly around the wound. A tangential loose or near-contact injury produces an elongated searing pattern and deposit of soot around the wound.
“Bullet wipe” is a residue from soot, soft lead, or lubricant, which may leave a gray or black rim or streak on the skin or clothing overlying an entrance wound (Fig. 19.7). This discoloration may also be found around the abrasion collar but is usually more prominent on clothing.
Determining whether a wound is an entrance or an exit wound should be based on the physical characteristics and physical evidence associated with the wound and never upon the size of the wound. The size of the exit wounds are the result of a bullet pushing and stretching the skin from inside outward. The skin edges are generally everted, with sharp but irregular margins (Figs. 19.12, 19.13, 19.14). Abrasion collars, soot, searing, and tattooing are not associated with exit wounds. Soot can be seen at an atypical exit wound site if the entrance wound is close to the associated exit wound. Soot can be propelled through the wound from entrance to exit when the wound track is extremely short. If this is noted, the soot deposition will be more pronounced at the entrance and only faintly observed within the exit wound.
Exit Gunshot Wound. A slit-like exit wound on the scalp from an intraoral gunshot. Exit wounds may take on a variety of appearances. (Photo contributor: William S. Smock, MD.)
Exit Gunshot Wound. Stellate tears in an exit wound from a .22 caliber long rifle bullet that impacted the radius and ulna. The stellate configuration of an exit wound should not be confused with that of a contact wound. Exit wounds lack soot and seared skin. (Photo contributor: William S. Smock, MD.)
High-Velocity Gunshot Wound. A perforating high-velocity gunshot wound to a lower extremity. The gaping exit wound resulted from the transfer of energy from the projectile to the tibia. The impact propelled multiple bony fragments through the skin. (Photo contributor: William S. Smock, MD.)
Exit wounds assume a variety of shapes and appearances and are not consistently larger than their corresponding entrance wounds. The size of an exit wound is determined primarily by the amount of energy transmitted to underlying tissue, bone for example, which is extruded from the wound. A bullet’s size, shape, and attitude as it exits as well as postinjury tissue swelling will affect its size. A bullet’s usual nose-first attitude can change upon entering the skin to a tumbling and yawing one. A bullet with sufficient energy to exit the skin in a sideways attitude or one that has increased its surface area by mushrooming may produce an exit wound larger than its entrance wound. Energy transferred to bone, with resultant ballistic fracture, may also result in an exit wound larger than the entrance wound (Fig. 19.14). A “false abrasion collar” or “shored exit” wound may mimic an entrance wound. This occurs when the epithelium is pressed against a supporting surface such as a floor, wall, chair, firm mattress, or wallet (Figs. 19.15 and 19.16).
Shored Gunshot Exit Wound. A “shored exit” or “false abrasion collar” associated with a gunshot wound of exit. The false abrasion collar results when the skin is supported by a firm surface as the bullet exits. Shored exits occur when epithelium is pressed against a supporting surface (ie, floor, wall, chair, firm mattress, or, as in this case, wallet). (Photo contributor: William S. Smock, MD.)
Wallet Causing Shored Gunshot Exit Wound. The wound seen in Fig. 19.15 occurred as a result of this wallet resisting the bullet’s exit. (Photo contributor: William S. Smock, MD.)
Graze wounds are considered atypical and result from tangential contact with a passing bullet. The direction of the bullet’s path may be determined by careful wound examination. The bullet produces a trough and may cause the formation of skin tags on the lateral wound margins (Fig. 19.17). The base of these tags points toward the weapon and away from the direction of bullet travel.
Graze Gunshot Wound. A deep graze wound from a handgun is seen. The dark wound margins are the result of drying artifact and should not be confused with the deposition of soot. (Photo contributor: Lawrence B. Stack, MD.)
Preservation of clothing, bullets, and cartridge cases is critical to the investigation of gun violence. Clothing should be place in separate paper bags and bullets in breathable containers. The microscopic marks on the exterior surface of a bullet can be used to identify the offending weapon. The use of booties on the ends of hemostats can prevent the loss of essential evidence and preserve these unique identifying microscopic marks from being altered or permanently destroyed (Fig. 19.18).
Suture Booties. The use of booties on hemostats prevents the identifying microscopic marks on the bullet’s surface from being damaged by handling. (Photo contributor: William S. Smock, MD.)
Distant-range gunshot wounds are inflicted from a distance of greater than 4 feet and there is no tattooing, soot, or searing associated with the wound.
Intermediate-range gunshot wounds are inflicted at a distances up to 4 feet and characteristically are associated with tattooing from partially burned and unburned gunpowder impacting the skin.
Near or close-contact gunshot wounds are defined as the maximum range at which soot is deposited on the wound or clothing and typically occur at a distance of 6 inches or less.
Contact gunshot wounds (barrel is in contact with the skin or clothing at time of discharge) vary in size but will include triangular tears, searing of the skin, and soot within or around the wound.
Abrasion collars, soot, searing, and tattooing are associated with entrance wounds.
Determination of whether a wound is an entrance or exit wound should only be based on the physical characteristics of the wound and clothing and not on the size of the wound.
The size of an exit wound is determined by: (1) energy transferred from the bullet to underlying tissue (bone pushed out), (2) bullet shape (mushroomed) and configuration, and (3) swelling of underlying tissue.
Emergency physicians should attempt to recognize, document, preserve, and collect short-lived evidence whenever the clinical situation allows.