A bruise is bleeding you can see without breaking the skin
Trauma crushes capillaries; blood seeps into tissue and paints the surface red, blue, or nearly black. Petechiae stay under three millimetres, purpura span three to ten, and larger blotches earn the name ecchymosis. Mild marks fade in about two weeks as the body reabsorbs the spill.
Clinicians call the lesion a contusion or hematoma of tissue. Blunt force—falls, surgery, sports—compresses vessels so that plasma and cells extravasate without an open wound. Colour tracks severity and vessel type: broken arterioles lean deep red, venules deep blue, mixed bleeds darker still. As haemoglobin breaks down, older patches shift toward green, yellow, or brown before the stain finally fades from view.
Size vocabulary matters for differential diagnosis. Petechiae stay under three millimetres and can follow straining, certain drugs such as warfarin, platelet trouble, or infections; purpura spans three to ten millimetres; larger blotches earn the name ecchymosis. Coagulopathies including haemophilia A, anticoagulant therapy, or medications such as betamethasone can seed ecchymoses even in children. Natural redheads may appear to bruise more, possibly because fair skin simply shows colour better despite normal clotting factors.
Most small bruises hurt briefly and heal alone within about two weeks, yet extensive or deep ones can signal fractures, organ injury, abuse, leukemia, or meningococcal disease when unexplained. Contracted muscle and tissue crushed against bone bruise harder; capillary toughness also shifts with age and illness. Shapes may echo the striking object, then swell larger hours later—so the story of a mark is written both at impact and in the slow chemistry afterward. Pathologists use that biology too: at autopsy, bruising around an abrasion shows the scrape was made while the person was still alive. For everyday knocks, care is modest—rest, ice, compression and elevation, painkillers such as NSAIDs, and gentle stretching later on.
Source: Bruise
