what is hematoma
1 A hematoma is a collection of blood outside of a blood vessel. 2  Symptoms of hematomas depend upon their location and whether adjacent structures are affected by the inflammation and swelling associated with the bleeding.3  Treatment of a hematoma depends upon which organ or body tissue is affected. Symptoms of hematomas depend upon their location and whether adjacent structures are affected by the inflammation and swelling associated with the bleeding. 2  Treatment of a hematoma depends upon which organ or body tissue is affected.