What causes a hematoma?

Trauma is the most common cause of a hematoma. When people think of trauma, they generally think of car accidents, falls, head injuries, broken bones, and gunshot wounds. Trauma to tissue may also be caused by an aggressive sneeze or an unexpected twist of a limb. When a blood vessel is damaged blood leaks into the surrounding tissue; this blood tends to coagulate or clot. The greater the amount of bleeding that occurs, the larger the amount of clot formation.

Blood vessels that are fragile may contribute to hematoma formation. For example, an aneurysm or weakening in a blood vessel wall may spontaneously leak.

There are many people who take blood thinners (anticoagulation) medications. Examples include warfarin (Coumadin), aspirin, clopidogrel (Plavix), prasugrel (Effient), rivaroxaban (Xarelto), and apixaban (Eliquis). These medications increase the potential for spontaneous bleeding and for hematomas to expand because the body cannot efficiently repair blood vessels and this allows blood to continually leak through the damaged areas.

Occasionally, diseases may occur that decrease the number of platelets in the bloodstream (thrombocytopenia) or their ability to function. The platelets are the cells in the bloodstream that help initiate blood clot and fibrin formation.

All of the above situations may exist independently to cause a hematoma or they may occur together. Continue Reading

Reviewed on 9/17/2015
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