In medicine, an embolism is the lodging of an embolus, which may be a blood clot, fat globule, gas bubble, in the bloodstream. This can cause a blockage in a blood vessel. Such a blockage (vascular occlusion) may affect a part of the body distanced from the actual site of the embolism. This is in contrast to a thrombus, which causes a blockage at the site of origin.