An intramuscular hematoma may be classified as traumatic or spontaneous (nontraumatic or pathologic). The presence of spontaneous hemorrhage usually indicates an underlying disease.
Conditions associated with intramuscular hematoma:
(1) hereditary coagulopathy such as hemophilia A or B
(2) acquired coagulopathy
(3) drug-induced coagulopathy (typically warfarin)
(4) tumor (hemangioma, sarcoma, etc)
(5) vascular disease (aneurysm, tear, etc)
Trauma causing a hematoma may be:
(1) blunt
(2) penetrating
(3) iatrogenic (such as an intramuscular injection)
(4) torsion as in exercise, sudden twisting or coughing
