Definition: (noun) A seroma is a swollen area of tissue filled with blood serum – a fluid component of your blood that contains no blood cells, platelets, or clotting factors. Seromas can occur after a surgery or injury, while your tissues are trying to heal. Your body will attempt to absorb the blood serum back into nearby tissues, but if the fluid builds up faster than your body can soak it up, it collects in one place and becomes a seroma. A seroma can occur just beneath your skin or deeper within your body.
A seroma is not the same as a hematoma
, another type of fluid-filled swelling. Seromas contain blood serum, but hematomas contain red blood cells. Many seromas can be cleared up with a needle aspiration, during which a fine needle is used to drain the fluid out of the swelling and allow the tissue to reunite and heal. If a seroma does not clear up in good time, the area around it can turn into scar tissue, known as a pseudobursa, which can be removed by surgery.