A 32-year-old man is brought to the emergency department following a motor vehicle accident. On examination, he has multiple injuries over his body. Regarding the forensic classification of mechanical injuries, all of the following statements about abrasions are TRUE EXCEPT:

Explanation

## Abrasion: Definition and Forensic Significance ### What is an Abrasion? **Key Point:** An abrasion is a superficial mechanical injury caused by tangential rubbing or scraping of the skin against a rough surface, resulting in loss of the epidermis and variable portions of the dermis. ### Characteristics of Abrasions | Feature | Details | |---------|----------| | **Depth** | Superficial; epidermis and upper dermis | | **Bleeding** | Minimal to moderate (capillaries in dermis may be breached) | | **Tissue Bridging** | Present across the wound (distinguishes from laceration) | | **Margins** | Irregular; no tissue bridging at edges | | **Direction** | Can indicate direction of force by pattern of tissue loss | ### Why Option 2 is Incorrect **High-Yield:** The statement "abrasions are always accompanied by minimal or no bleeding" is FALSE. While abrasions are superficial, they frequently involve the dermis, which contains capillary networks. Bleeding can be moderate, especially if the dermis is extensively abraded. The depth of the abrasion determines the degree of bleeding—deeper abrasions involving dermal vessels will bleed more freely. ### Forensic Significance **Clinical Pearl:** Abrasions are valuable in forensic medicine because: - They indicate the direction of force application (tissue loss points away from the direction of force) - They help establish the sequence of injuries when multiple injuries are present - They can reveal the nature of the abrading surface (e.g., road rash pattern suggests asphalt) - Tissue bridging across the wound is pathognomonic and distinguishes abrasions from lacerations ### Distinguishing Abrasion from Laceration **Key Point:** The presence of **tissue bridging** (strands of tissue crossing the wound) is the hallmark feature that separates abrasions from lacerations. Lacerations show tissue bridging; abrasions show loss of tissue with irregular margins. [cite:Reddy's Forensic Medicine 33e Ch 8]