A puncture wound is the piercing of the body by a sharp-tipped object. It can be as trivial as pricking a finger with a needle or drawing pin, or as serious as the fatal penetration of the heart or lungs with a knife. Puncture wounds tend to have more depth than width, which distinguishes them from cuts, where the reverse is true. In a forensic context, the most significant kinds of puncture wounds are stab wounds, which are often fatal.
A stab wound can be homicidal, suicidal, or accidental and autopsy can often shed light on the manner of death in such cases. Many different weapons can be used to inflict stab wounds. Typically, a knife is used but screwdrivers, fragments of glass , hat pins, or hypodermic needles may also cause stab wounds. The weapon need not even be held by an assailant. In some accidents, people sustain broken ribs which puncture the lungs, or fall on broken glass or spiked railings.
During an autopsy, the pathologist will look at the location, depth, and track of puncture wounds. He or she will try to work out from what direction the weapon entered the body, the track it took, and the damage caused. X rays can be useful in establishing the track of the wound and may also be indicative of the dimensions of the weapon. It is also important to examine any damage to clothing; the direction of any tears and blood patterns may reveal something of the victim's position relative to the assailant.
Relatively little force need be applied to the weapon to build up a penetrating pressure on its pointed end. Once the weapon has penetrated the victim's clothes, then the body itself offers relatively little resistance to its penetration, unless it impacts on bone. Weapons that break into bone will have been applied with considerable force. Often, the tip of the weapon is left behind in the victim's body and, if the pathologist retrieves it, they will have a valuable piece of evidence .
Wounds that enter an organ are known as penetrating and if they also pass out the other side they are known as perforating. Much of the bleeding in a stab wound is internal. Indeed, a trivial looking puncture of the skin may conceal a very deep and possibly fatal wound. Cause of death is usually massive hemorrhage. Most deaths by stabbing are homicidal in nature and common sites for the wounding are the heart, abdomen, back, and throat. The pathologist will want to deduce as much as possible about the circumstances of the event by the analysis of the nature of the stab wounds.
see also Knife wounds; Wound assessment.