A 28-year-old man is brought to the trauma centre with a gunshot wound to the right upper abdomen. The entry wound measures 1.2 cm with a well-defined abrasion collar and no visible soot or powder tattooing. The exit wound on the left flank measures 3.5 cm with irregular, everted margins and tissue loss. On examination, he has signs of peritoneal irritation. What can be inferred about the bullet's trajectory and wound characteristics?

Question

Accepted Answer

D. The bullet was fired from >1 m distance; the larger exit wound indicates a tumbling or deformed bullet. ## Analysis of Entry and Exit Wound Characteristics

### Entry Wound Assessment

**Key Point:** The entry wound is smaller and more regular than the exit wound. The **absence of soot and powder tattooing** indicates the shot was fired from **>1 m (distant range)**.

**High-Yield:** Entry wounds are typically smaller than exit wounds because:
1. The bullet is intact and moving at maximum velocity at entry
2. The abrasion collar forms from the bullet's friction against skin
3. Tissue damage is confined to the bullet's diameter

### Exit Wound Characteristics

The exit wound (3.5 cm) is significantly larger than the entry wound (1.2 cm). This size discrepancy occurs because:

1. **Bullet deformation or tumbling** — as the bullet travels through tissue, it may deform (mushroom), yaw (tumble), or fragment
2. **Temporary and permanent cavity formation** — the bullet creates a temporary cavity much larger than its diameter, causing explosive tissue disruption
3. **Tissue elasticity** — exit wounds have irregular, everted (turned-out) margins because tissues are pushed outward

### Comparison: Entry vs. Exit Wounds

| Feature | Entry Wound | Exit Wound |
|---|---|---|
| **Size** | Small, regular (≈bullet diameter) | Large, irregular (>bullet diameter) |
| **Margins** | Abrasion collar, inverted | Everted, ragged, tissue loss |
| **Shape** | Round or oval | Irregular, stellate |
| **Soot/Tattooing** | Present at close range | Absent (internal wound) |
| **Predictability** | More consistent | Highly variable |

### Why This Exit Wound Is Large

**Clinical Pearl:** A large exit wound does NOT necessarily mean the bullet was deformed at entry. Instead, it reflects:
- **Bullet tumbling** in tissue (yaw angle increases tissue damage)
- **Temporary cavity expansion** (hydrostatic shock)
- **Bullet fragmentation** (especially if it strikes bone or organs)

In this case, the bullet likely tumbled or deformed **during its passage through abdominal organs**, not because it was fired from close range.

**Mnemonic: EXIT WOUND SIZE FACTORS — CAVITY**
- **C**avity (temporary cavity from hydrostatic shock)
- **A**ngle (bullet yaw/tumbling)
- **V**elocity (retained kinetic energy)
- **I**ntegrity (bullet deformation/fragmentation)
- **T**issue (elasticity and organ involvement)
- **Y**ield (tissue resistance)

### Range Determination

The **absence of soot and powder tattooing** is the most reliable indicator of range:
- Soot = 0–15 cm
- Powder tattooing = 15 cm–1 m
- **No soot or tattooing = >1 m** ✓

The large exit wound is a consequence of the bullet's behavior in tissue, not the range of fire.

Answer

A. The bullet was fired from contact range; the exit wound size indicates a high-velocity, non-deforming bullet

Answer

B. The bullet was fired from 15 cm–1 m distance; the exit wound is larger because the bullet has lost kinetic energy

Answer

C. The bullet ricocheted off bone; the irregular exit wound confirms a secondary trajectory

Explanation

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