Can any doc tell me what is a hematoma and how heparin can cause it if given intra-muscular?

Coagulated blood: Heparin in the muscle or anywhere reduces your ability to clot so you bleed easier and longer than normal. If you are on Heparin an have a trauma to the leg for example you may have some bleeding , that blood eventually will coagulate and begin to b absorbed back into the system. Blood outside of the blood vessels is a hematoma ( a "tumor" of blood) normally not dangerous ie "black & Blue"