A 28-year-old woman is brought to the casualty after an assault with a kitchen knife. She has two wounds over the left upper abdomen: one is 3 cm long with clean, sharp edges and minimal surrounding bruising; the other is 0.5 cm in diameter, deep, and narrow with no surrounding tissue damage. Both wounds are bleeding minimally. On examination, she is alert, blood pressure 118/76 mmHg, heart rate 92/min. Abdominal examination reveals mild tenderness over the left upper quadrant. Which wound is more likely to cause serious internal injury, and why?

Explanation

## Stab vs. Incised Wounds: Depth and Internal Injury Risk ### Wound Characterization **Key Point:** The critical distinction between incised and stab wounds lies in the **depth-to-length ratio**: - **Incised wound:** Length > depth; produced by a sharp instrument moving across the skin (e.g., slashing motion). - **Stab wound:** Depth ≥ length; produced by a sharp instrument penetrating perpendicularly into tissues (e.g., stabbing motion). In this case: - **3 cm wound:** Incised (length >> depth, clean margins, minimal bruising). - **0.5 cm wound:** Stab (very small external opening, deep penetration, narrow tract). ### Why Stab Wounds Are More Dangerous ```mermaid flowchart TD A[Stab Wound]:::outcome --> B[Small external opening]:::outcome A --> C[Deep penetration into body cavity]:::outcome B --> D[Minimal external bleeding]:::outcome C --> E[High risk of organ injury]:::urgent E --> F[Liver, spleen, kidney, bowel]:::outcome D --> G[False reassurance from appearance]:::urgent G --> H[Delayed diagnosis if not explored]:::urgent ``` **High-Yield:** Stab wounds are **deceptively dangerous** because: 1. **Small external opening** → minimal bleeding → false impression of superficiality. 2. **Deep penetration** → can traverse the entire abdominal wall and injure solid organs (liver, spleen, kidney) or hollow viscera (stomach, small bowel). 3. **Narrow tract** → difficult to assess depth clinically; exploration may be needed. ### Clinical Implications **Clinical Pearl:** A patient with a stab wound may appear haemodynamically stable initially but can deteriorate rapidly if a solid organ (liver, spleen) has been injured. The absence of external bleeding does NOT exclude internal bleeding. **Warning:** Haemodynamic stability and alertness are **not reassuring** in stab wounds. Intra-abdominal bleeding can accumulate in the peritoneal cavity without immediate signs. Serial abdominal examination, imaging (CT with IV contrast), and sometimes diagnostic laparoscopy or exploratory laparotomy are indicated. ### Incised Wounds (3 cm) Incised wounds: - Tend to be more superficial because the slashing motion distributes force over a longer distance. - Have more obvious external bleeding due to larger wound surface area. - Are less likely to penetrate deep body cavities if confined to the skin and subcutaneous tissues. - Still require exploration if over the abdomen or chest to rule out deep structure involvement. ### Management Comparison | Feature | Incised Wound (3 cm) | Stab Wound (0.5 cm) | |---------|---------------------|---------------------| | External appearance | Large, obvious | Small, deceptive | | Visible bleeding | Often brisk | Often minimal | | Depth assessment | Easier to gauge | Difficult to assess | | Risk of organ injury | Lower (if superficial) | Higher (deep penetration) | | Management | Exploration + closure if safe | Mandatory exploration or imaging | **Key Point:** In abdominal stab wounds, the principle is **"explore all stab wounds"** — either by clinical exploration under local anaesthesia, diagnostic laparoscopy, or CT imaging with IV contrast. Do not rely on haemodynamic stability or absence of peritoneal signs. [cite:Parikh's Textbook of Forensic Medicine Ch 5]