Stab wounds are also known as puncture wounds. These are the piercing wounds that are produced by the application of mechanical force along the long axis of a narrow or pointed object. They are classified mainly based on the depth of penetration and based on the causative weapon.
Based on the depth they can be penetrating or perforating wounds. Based on the causative weapon it can be an incised stab wound or lacerated stab wound. Both of these are further subdivided into penetrating and perforating wounds.
Penetrating wounds are those types of wounds that terminate in the tissue/organ and cavity. Mostly only one surface wound will be present on the body due to the entry of the blade and no exit wound as the stab terminates in the tissue, organ, or cavity. Most deaths from stab wounds are homicidal, especially if found in an inaccessible area. The wounds are multiple, widely scattered, and deeply penetrating, involving the chest and abdomen.
In perforating wounds, there will be two surface wounds over the body. One caused by the entry of the weapon and another caused by the exit of the weapon. The entry wound is usually larger than the exit wound because the weapon tapers towards the tip. The edges of the entry wound are mostly inverted and that of the exit wound will be everted. Joining the entry and exit wound can give the direction of infliction of the injury.
Features of Stab Wounds
- The edges of stab wounds are clean-cut and inverted. The margins can be seen everted if these wounds are inflicted on a fatty area like the abdomen or gluteal region.
- The margins do not show bruising or abrasion. But sometimes when the weapon is inserted completely, then due to the hilt guard slight abrasion or bruising might be seen. The hilt mark will be symmetrical if the knife strikes the skin at a right angle and it will be prominent above the wound if the knife strikes at a downward angle.
- If the weapon is blunt-edged, then the wound will have abraded or ragged margins.
- The length of the wound is comparatively less than the width of the weapon because of stretching of the skin. The wound can get widened due to the movement while withdrawing the weapon from the body.
- The maximum possible width of the weapon can be estimated approximately if the edges of a gaping wound are brought together. If elasticity and laxness are considered, the width may change only by 1 or 2 millimeters. If the skin is stretched, then the wound will be long and thin which will become short and broad when the skin is relaxed.
- The depth of the wound will be more than the length and breadth.
- In a stab wound on the anterior wall of the chest, the postmortem depth is greater than it was during life, because of the collapse of the lung. If the stab is on the back of the chest, the depth of the wound will be less, as the lungs will collapse posteriorly.
- A thin, slender, double-edged knife will penetrate more deeply than an equally sharp, wide, single-edged blade inserted with the same force. A blunt-pointed instrument requires considerable force to puncture the skin and penetrate the soft tissues.
- Apart from bone and calcified cartilage, the skin followed by the muscle is most resistant to knife penetration. Uncalcified cartilage is easily penetrated by a sharp knife, though more force is required. Forcible stabs from a strong, sharp knife can penetrate ribs, sternum, or skull.
- Obstruction due to tough thick clothing offers more resistance and hence requires greater force for penetration.
- The size and shape of a stab wound in the skin are dependent on the type of weapon, cutting surface, sharpness, width, and shape of the weapon, body region stabbed, the depth of insertion, the angle of withdrawal, the direction of thrust, the movement of the blade in the wound, cleavage direction, the movement of the person stabbed, and the condition of tension or relaxation of the skin.
- The velocity of the knife at the time of impact, as a fast-moving knife would penetrate the tissues with greater ease than one exercising slow steady pressure.
- Ellipse is the most common shape, there is a wide range of shapes of these wounds. Strangely shaped surfaces, as well as the visceral wounds, may be observed such as ‘A’ or ‘V’ or ‘Λ’ or some may be square or diamond-shaped and still like cruciate, stellate, etc
Difference Between Homicidal, Suicidal and Accidental Stab Wounds
|Traits||Suicidal Stab Wounds||Homicidal Stab Wounds||Accidental Stab Wounds|
|Number||Mostly single||Frequently multiple||Usually single|
|Site||Accessible precordial area or upper abdomen.||Can be present anywhere.||Maybe present anywhere.|
|Tentative wounds||Maybe present around the site of the fatal wound.||Maybe present. It is rare. If present, then it will be away from the fatal wound.||Absent|
|Clothing||Removed from the injured area.||Normally not disturbed||Not disturbed|
|Defense wounds||Absent||Mostly present||Absent|
Stab wounds can indicate the type of weapon used, dimension of the weapon, movement of the weapon in the wound, depth of thrust, the direction of thrust. The amount of force used, age of wounds and manner of infliction whether suicidal/homicidal/accidental can also be known.