Definition for Bruise
From Biology Forums Dictionary
A bruise, also called a contusion, is a type of hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep, hemorrhage, or extravasate into the surrounding interstitial tissues. Not blanching on pressure, bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle, or bone. Bruises are not to be confused with other lesions primarily known by their diameter. These lesions include petechia (< 3 mm caused typically by platelet disorders), purpura (3 mm to 1 cm caused typically by inflammation of the small blood vessels known as vasculitis), and ecchymosis (>1 cm caused typically by coagulation disorders), all of which also do not blanch on pressure, and are caused by internal bleeding not associated with trauma (e.g., platelet or coagulation disorder).
