I am happy to give you some general information about bruising, but recommend that if you are very concerned about the bruise
, or bruise easily, you get checked out by your primary care physician
. A bruise is the common term for a hematoma, which is the medical term for seeping of blood into interstitial tissues as a result of trauma. This can happen at multiple different depths, from the skin and subcutaneous tissues, all the way down to the bone. Usually it is a fairly superficial problem within the skin or subcutaneous tissues and is not typically dangerous. It can be dangerous if there is an expanding hematoma, but it doesn't sound like this is the case in your situation. The collection of the blood within the tissues is what gives the typical color (aka "black and blue"). The immune system has cells which will phagocytose the red blood cells and start to break down the hemoglobin which is what actually carries the oxygen in your blood cells. This converts the hemoglobin (blue/purple) to biliverdin (green), to bilirubin (yellow), to hemosiderin (golden-brown). This is why a bruise changes color as it matures. This process is dependent on the person's immune system, as well as the blood flow to the area that has the bruise. It can take a while for the bruise to mature as a result (often a few weeks). If the bruise seems to be expanding, or if it does not seem to be maturing (changing color) as expected, I would recommend getting it checked out sooner rather than later.