What is an embolism?

An embolism refers specifically to the obstruction of a blood vessel caused by a clot or other substance that has traveled from a different location in the body. This clot, known as an embolus, can originate from various sources, such as a thrombus (a blood clot that forms at the site of injury or vascular disease) or from materials like fat or air that enter circulation.

When an embolus travels through the bloodstream, it can become lodged in a narrower part of a blood vessel, leading to impaired blood flow and potentially causing tissue ischemia, heart attack, or stroke, depending on the location of the obstruction. This process underscores the importance of understanding how clots can become dangerous when they detach from their original site and travel through the vascular system.

The other options describe different aspects of clot formation and blood flow issues but do not accurately define an embolism. Local blood clots that do not dislodge do not qualify as emboli, and simply having reduced blood flow or obstruction from a clot formed locally also does not encompass the definition.