What's a Hematoma?
A hematoma is a kind of bruise that happens when an injury causes blood to collect and pool under the skin. The "hema" part of the word means blood, which you see under your skin if you get a bad bump — the blood vessels break, letting the blood leak out. But then your body goes to work to clean things up. Before you know it, the black and blue color has faded to green or yellow and then it's all gone.