Abrasions

What it is

An abrasion (excoriación) is the most superficial blunt-force injury: the epidermis is lost, leaving a bare surface that bleeds little. Clinically it is minor, but forensically it says a lot: it proves contact, shows that the object moved across the skin at an angle, and sometimes leaves the imprint of the object (a sole, a cord, a fingernail). That is why it is described with the same care as a serious wound.

How to tell it apart

• Versus a bruise: in an abrasion the epidermis is missing; in a bruise the skin is intact and the blood lies beneath.
• Versus a laceration: an abrasion does not go through the full thickness of the skin.
• Postmortem abrasion: yellow-brown, parchment-like, with no reaction around it (see vital reaction).
• Everyday or self-inflicted scrapes can look like assault abrasions: do not conclude from shape alone.

How to recognise it

• An area of skin without epidermis, red and moist at first; a scab forms later.
• Scratch: linear and narrow (nails, points).
• Graze (sliding or brush abrasion): broad, with parallel striations in the direction of movement.
• Pressure or imprint abrasion: reproduces the shape of the object pressed on the skin.

How it forms

• An object rubs the skin at an angle, with relative movement and friction, and removes the epidermis.
• In an imprint, perpendicular pressure crushes the epidermis against the object and copies its relief.
• The direction of rubbing leaves the detached skin heaped up at the far end.

Step by step

1. Locate each abrasion against fixed anatomical landmarks and measure it in two dimensions.
2. Describe shape, colour, scab and any associated bruise.
3. Find the end where epidermis piles up to state the direction of force.
4. Look for and keep debris (soil, glass, fibres, hairs) before cleaning.
5. Photograph with a scale before any wound care.

Next step: what to do and document

• Before cleaning, photograph with a scale and collect visible debris; package and label it with chain of custody.
• Record location, size, shape, likely direction of force and any pattern.
• On the neck, also examine the eyes, mucosa and voice, and record what the patient says (see strangulation).
• If the injuries do not match the account, in a child, an older adult or a victim of violence, start the protection pathway and the mandatory notifications.

Common mistakes

• Calling an abrasion on the neck of an intimate-partner violence victim "a trivial graze".
• Cleaning or dressing before photographing and collecting debris.
• Stating the manner (assault, accident) from the shape of the abrasion alone.
• Mistaking a parchment-like postmortem abrasion for an injury in life.

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Elsewhere in DurgiPedia

• Mandatory reporting: public health, violence and abuse
• Mechanical and electrical injury: abrasion, contusion, laceration, wounds

Connections

← All of forensic medicine

Educational content on forensic and legal medicine; not legal advice and no substitute for the technical guides of Colombia's National Institute of Legal Medicine and Forensic Sciences. Laws change: each page links the official text and says when it was last checked. For a real case, follow the guide in force and ask the competent authority.

Sources: Trauma Forensics in Blunt and Sharp Force Injuries (Journal of the West African College of Surgeons (PMC), 2022); Blunt Force Trauma (StatPearls) (NCBI Bookshelf, StatPearls Publishing, 2023).

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