## Distinguishing Abrasion from Contusion **Key Point:** The depth of tissue involvement is the fundamental difference between abrasion and contusion. ### Abrasion (Graze) - Involves only the **epidermis** (superficial layer) - Caused by tangential rubbing or scraping against a rough surface - No bleeding (epidermis is avascular) - Leaves a characteristic pattern of the object that caused it - Heals without scarring if infection does not occur ### Contusion (Bruise) - Involves **dermis and subcutaneous tissue** (deeper layers) - Caused by blunt force trauma without breaking the skin - Results in extravasation of blood into tissues → discoloration - Follows predictable color changes: red → blue/purple → green → yellow → brown - May leave permanent scarring if severe **High-Yield:** Abrasion = **superficial, no blood**; Contusion = **deep, with blood extravasation**. ### Comparison Table | Feature | Abrasion | Contusion | | --- | --- | --- | | **Depth** | Epidermis only | Dermis + subcutaneous | | **Bleeding** | None (avascular) | Present (blood extravasation) | | **Appearance** | Red/raw, no discoloration | Discolored (blue/purple initially) | | **Pattern** | Often shows object pattern | Follows blunt force outline | | **Healing** | Quick, no scar | Slower, may scar | **Clinical Pearl:** In forensic examination, the absence of bleeding in an abrasion helps confirm it is superficial and caused by friction, not blunt impact.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.