A 28-year-old male is brought to the hospital after sustaining a gunshot wound to the abdomen. On examination, there is a single entry wound in the epigastric region with an abrasion collar and soot deposition around the margins. The wound is 8 mm in diameter. No exit wound is found despite thorough examination. Abdominal imaging reveals multiple organ injuries with significant intra-abdominal bleeding. Which of the following best explains the absence of an exit wound in this case?

Explanation

## Absence of Exit Wound in Gunshot Injuries **Key Point:** When a bullet lacks sufficient kinetic energy to traverse the full thickness of the body, it becomes lodged within tissues, resulting in an entry wound without a corresponding exit wound. This is common in low-velocity gunshot wounds or when the bullet strikes dense structures. ### Factors Determining Exit Wound Formation | Factor | Impact on Exit Wound | |--------|---------------------| | **Bullet velocity** | Higher velocity → exit wound likely; Low velocity → lodgement likely | | **Bullet caliber/mass** | Larger mass → greater penetrating power | | **Tissue density** | Dense organs (liver, bone) → greater energy loss | | **Distance from gun** | Contact/close range: lower velocity; Distant: higher velocity | | **Bullet design** | Hollow-point/soft-nose: expands, loses velocity; Full metal jacket: better penetration | **High-Yield:** The presence of an abrasion collar and soot deposition confirms this is an entry wound. The absence of an exit wound indicates the bullet did not have sufficient kinetic energy to exit the body. ### Mechanism of Bullet Lodgement 1. Bullet enters with initial kinetic energy: $KE = \frac{1}{2}mv^2$ 2. Energy dissipated through tissue destruction and temporary cavity formation 3. If remaining kinetic energy is insufficient to overcome tissue resistance → bullet stops 4. Result: single entry wound, no exit wound **Clinical Pearl:** In abdominal gunshot wounds, multiple organ injuries can occur even without an exit wound because the temporary cavity created by the bullet can cause significant tissue damage beyond the direct wound tract. **Mnemonic: VELOCITY** — Vital factors for exit wound formation: - **V**elocity of projectile (must be sufficient) - **E**nergy remaining after entry - **L**odgement vs. penetration - **O**rgan density encountered - **C**aliber of weapon - **I**mpact angle - **T**issue resistance - **Y**ield of projectile (deformation/fragmentation) **Warning:** Do not assume all gunshot wounds produce exit wounds. Low-velocity weapons (air guns, older firearms) or bullets striking dense structures commonly lodge within the body.