Gunshot injuries are classified as entrance, exit, or atypical (grazing) wounds. Physical findings in and around these wounds may offer evidence as to the actual mechanism, supporting or refuting the initial history given to the provider. As these findings may be transient, the emergency physician must be diligent in recognizing and documenting them at the time of presentation.
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.
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 projectile expelled from the muzzle that reaches the skin. There is no 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 (Fig. 19.3).
Distant Gunshot Wound. The elliptical abrasion collars associated with these gunshot wounds of entrance indicate that the projectile passed from right to left. The range of fire is classified as distant or indeterminate based on the lack of carbonaceous material or gunpowder tattooing. (Photo contributor: William S. Smock, MD.)
"Comet-Tailed" Abrasion Collar. The "comet tail," abrasion collar located at the superior aspect of the wound indicates the bullet entered the wound at an angle. The "comet tail" also indicates the bullet's direction of travel; anterior to posterior. (Photo contributor: William S. Smock, MD.)
Entrance Wound on Sole. Entrance wounds on the soles of the feet do not generate abrasion collars due to the thickness of the skin. (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. 19.4). This tattooing cannot be wiped away. Clothing and hair, ...