Haematoma refers to a collection of blood outside of the blood vessels, which gathers in body tissues or cavities. Haematoma are most commonly apparent as bruising to the skin, and are caused by internal bleeding into the extracellular space following blunt trauma - this can include accidents, falls and surgery.
Haematoma can also refer to internal bleeding in organs, this tends to have no visible external symptom.
Haematomas under the surface of the skin can manifest as un-raised bruising or as hardened lumps. These lumps are blood sacs which aim to keep internal bleeding localised and to a minimum.
Haematoma usually dissolve, and can typically be treated surgically if they do not. In some cases, particularly with a larger haematoma, they can migrate to nearby areas of the body due to the effects of gravity.
Bruising from haematoma can sometimes be painful, but smaller bruises do not usually pose a health risk. Larger haematoma that do not fade over time could by a symptom of a more serious condition, and should be checked by a doctor.
Haematoma and cosmetic surgery
Most invasive cosmetic surgery procedures will result in a degree of bruising to the treated area for some time following surgery, but this will gradually diminish during the recovery period.
Non surgical treatments do not typically result in haematoma, as they are non invasive.