hematoma
Meaning of hematoma: A bruise stains the tissue, while a hematoma occupies space, and the trouble it causes comes mostly from what it presses on.
Definition of hematoma
A hematoma is a pooled collection of blood, clotted or partly clotted, that has escaped a damaged vessel and gathered outside it within a tissue, an organ or a body space. It ranges from a raised lump under the skin to a large collection deep inside the body, and its effects come mainly from the room it takes up.
How hematoma is built
- hem/o, hemat/o Combining form · Greek blood
- -oma Suffix · Greek tumour, mass, swelling
A medical term is read from its ending backwards: the suffix first, then the prefix, then the root. See all 223 word parts.
How does it differ from a bruise?
By whether the blood is spread out or pooled. A bruise is blood seeping diffusely through tissue from tiny broken vessels, so it discolors the skin but stays flat. A hematoma is a discrete pocket, usually firm, raised and tender, and it can often be felt as a distinct lump. Both pass through the same sequence of colors as the blood pigment is broken down and cleared, moving from red and purple through green to yellow and brown, which is chemistry rather than healing speed. The larger the pocket, the longer clearance takes, and a big one may leave a firm scarred knot for months or drain into the tissue below under gravity, appearing some distance from where the injury landed.
Why does the location matter so much?
| Site | What makes it distinctive |
|---|---|
| Between skull and its lining | Usually from a torn artery after a blow to the temple, and can worsen quickly |
| Beneath that lining | Usually from stretched veins, common in older adults, and may build slowly over weeks |
| Within an organ or its capsule | Silent until the capsule tears and blood spills into a body cavity |
| Inside a muscle compartment or under a nail | Enclosed by tissue that cannot stretch, so pressure rises and causes pain |
Soft tissue with room to swell absorbs a small bleed without incident. A confined space does not. Inside the skull, inside the sheath around a muscle or beneath a fingernail, the collection has nowhere to expand, so pressure climbs and squeezes nerves and the small vessels feeding the area. That is the whole reason two hematomas of identical size can be trivial in one place and urgent in another.
What makes one more likely?
Anything that increases bleeding or weakens the vessel wall. Medicines that thin the blood or block platelets are the commonest contributor, along with a low platelet count and inherited clotting disorders. Vessels grow more fragile and skin thinner with age, which is why an older person can develop a sizable collection from a knock that would not mark a younger one. Procedures supply the rest: a needle entering a vein, a biopsy, a catheter site or a surgical wound all breach a blood vessel deliberately, and a hematoma at such a site is among the more frequent minor complications. Firm pressure over the site after the needle is withdrawn is the standard means of limiting it.
Used in a sentence
A hematoma was identified at the injection site following the procedure.
Good to know
A hematoma beneath the skin is essentially a larger, deeper bruise, while a hematoma within the skull is classified by its precise location relative to the brain's surrounding layers, a distinction that significantly affects clinical urgency.
Word origin
Where “hematoma” comes from
Formed from Greek haima, meaning blood, and -oma, meaning tumor or swelling.