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Classification of Wounds

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I. Classification by Cause / Aetiology

A. Mechanical Wounds

1. Abrasion (Graze)

• Superficial damage to the epithelial covering of skin/mucosa caused by friction between a weapon and body surface
• The epidermis is scratched off; deeper layers intact
• A scab of dried blood forms, followed by granulation tissue and healing
• Sub-types:
  • Linear / Scratch abrasion - caused by horizontal friction from a pointed weapon; wider at start, heaping of epithelium at the end (indicates direction of force)
  • Graze abrasion - wider area, multiple parallel scratches
  • Pressure / Imprint abrasion - force applied perpendicularly, leaves the pattern of the weapon (e.g., tyre mark, ligature mark)
  • Degloving / Grinding abrasion - severe shearing/grinding force causes flaying of tissue

Key exam point: Abrasions heal without scarring (superficial) and can indicate the direction of force.

• PC Dikshit Textbook of Forensic Medicine and Toxicology, p. 177

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2. Contusion (Bruise)

• Caused by blunt force that damages subcutaneous blood vessels without breaking the skin
• Blood extravasates into surrounding tissues
• Important exam points:
  • Delayed bruising - deep bruises (abdomen, thigh) may not appear for hours or days
  • Shifting of bruise - blood gravitates through loose areolar tissue to a distant site:
    • Anterior cranial fossa fracture → "raccoon eyes" (periorbital bruising)
    • Basal skull fracture → Battle's sign (bruising behind the ear)
    • Calf injury → blood shifts to the ankle

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3. Lacerated Wound

• Caused by blunt force tearing the tissues
• Sub-types: split laceration (skin splits over a bony prominence), stretch laceration (skin overstretched), avulsion/degloving, cut laceration (heavy sharp-edged instrument)
• Characters of a lacerated wound:
  • Margins are irregular and bruised
  • Deeper tissues are unevenly divided
  • Hair bulbs are crushed (not cut cleanly)
  • Less haemorrhagic than incised wounds
  • Foreign matter may be present
  • Shape/size may not correspond to the weapon

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4. Incised Wound (Slash/Cut)

• Produced by sharp-cutting weapons: knife, razor, dagger, blade, sword, broken glass
• Defined as a wound longer than it is deep (if deeper than it is wide = stab wound)
• Characters of an incised wound:
  • Margins are clean, sharp, and smooth (no bruising)
  • Edges fall apart (gape) due to tissue retraction
  • More haemorrhagic than lacerated wounds (blood vessels cleanly cut)
  • Hair bulbs are cleanly cut (not crushed)
  • No foreign matter
  • Depth greatest at beginning, tailing off at end (tailing/fishtail)
  • Shape and approximate size corresponds to the instrument

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5. Stab / Puncture Wound

• Caused by sharp-pointed weapons (knife, nail, spike); wound is deeper than it is wide
• May involve internal organs without an alarming external appearance
• Shape on skin depends on: single-edged vs double-edged weapon, weapon width, Langer's cleavage lines
• Key distinction table (high-yield):

• The Essentials of Forensic Medicine and Toxicology, 36th ed.

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6. Firearm Wounds

• Divided into entry wound and exit wound
• Entry: punched-out, inverted margins, zone of tattooing/burning at close range
• Exit: larger, everted, irregular margins, more bleeding

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B. Thermal / Burn Wounds (by depth)

• 22nd Edition Pye's Surgical Handicraft

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C. Chemical, Electrical, and Radiation Wounds

• Chemical burns: acid burns (coagulative necrosis - form an eschar) vs alkali burns (liquefactive necrosis - deeper, more dangerous)
• Electrical burns: entry and exit wounds, iceberg effect (internal damage far exceeds surface appearance)
• Radiation: Slow, progressive tissue damage

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II. Classification by Relation to External Environment

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III. Surgical Wound Classification (CDC / NRC) - High-Yield for Surgery Exams

• Current Surgical Therapy, 14th ed.; Bailey and Love's Short Practice of Surgery, 28th ed.

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IV. Classification by Depth

• Epidermal - only epidermis (abrasion)
• Dermal - into dermis (superficial or deep partial thickness)
• Full-thickness - through entire skin into subcutaneous tissue
• Penetrating - into a body cavity
• Perforating - through-and-through into a hollow viscus

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V. Classification by Time / Contamination

• Acute wound - fresh, less than 4-6 hours old (amenable to primary closure)
• Chronic wound - fails to proceed through normal healing (pressure ulcers, diabetic foot, venous ulcers)

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VI. Classification by Complexity (Bailey & Love summary)

• Simple - single tissue layer
• Complex - multiple tissue layers involved
• Significant soft-tissue loss - requires reconstructive surgery

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Exam Quick-Recall Summary