bruise
Meaning of bruise: Blood that escaped a broken vessel and has nowhere to go, changing color over days as the body dismantles it.
Definition of bruise
A bruise is a patch of discolored skin caused by blood leaking from small vessels damaged under an intact surface. Because the skin is not broken, the blood stays trapped in the tissue and is cleared slowly. The mark is tender at first, does not fade when pressed, and shifts through a sequence of colors as the trapped hemoglobin is broken down.
Why does a bruise change color?
The colors track the dismantling of hemoglobin, the red pigment carried inside the escaped blood cells. Fresh blood beneath the skin looks red, then dark purple or blue as its oxygen is used up and the skin filters the light passing through it. Scavenging cells then break the pigment down in steps, and each product has a color of its own: green, then yellow, then a brownish stain that fades last. A bruise therefore ages visibly, although the pace varies widely between people and between sites on the same person.
What are the names for different sizes?
Bleeding under the skin is named by how large the affected area is and whether it forms a lump, and the words are not interchangeable.
| Term | What it describes |
|---|---|
| Petechiae | Pinpoint spots of leaked blood, often appearing in showers |
| Purpura | Small patches, larger than pinpoint spots |
| Ecchymosis | A flat, larger area of blood in the skin: the everyday bruise |
| Hematoma | Blood collected into a pocket, raising a firm lump |
| Contusion | The injury itself, meaning tissue bruised by a blow |
When is easy bruising more than an injury?
When bruises appear without a remembered knock, in places that rarely get knocked, or in numbers out of keeping with ordinary life. The usual explanations are unrelated to one another. Skin and its supporting tissue thin with age, so small vessels tear under minor force. Medicines that thin the blood or block clotting extend any bleeding that starts. Steroid treatment thins the skin in much the same way. A shortage of platelets, the cell fragments that plug damaged vessels, allows bleeding from vessels that would otherwise seal themselves, and thrombocytopenia of that kind is why an unexplained crop of bruises is investigated with a blood count.
Also known as
Used in a sentence
A bruise was present over the lateral thigh with no break in the overlying skin.
Good to know
The color sequence of a bruise varies widely between people and between sites, so the appearance of one is not a reliable guide to when the injury happened.