Blood clots (fibrin clots) are the clumps that result from coagulation of the blood. A blood clot that forms in a vessel or within the heart and remains there is called a thrombus. A thrombus that travels from the vessel or heart chamber where it formed to another location in the body is called an embolus, and the disorder, an embolism. For example, an embolus that occurs in the lungs is called a pulmonary embolism.

Sometimes, a piece of atherosclerotic plaque, small pieces of tumor, fat globules, air, amniotic fluid, or other materials can act in the same manner as an embolus.

For more information, see the following:

• Arterial embolism
• Pulmonary embolism
• Deep venous thrombosis
• Renal vein thrombosis
• Atheroembolic renal disease
• Thrombophlebitis
• Stroke
• Heart attack
• Angina

Thrombi and emboli can firmly attach to a blood vessel and partially or completely block the flow of blood in that vessel. This blockage deprives the tissues in that location of normal blood flow and oxygen. This is called ischemia and if not treated promptly can result in damage or death (infarction or necrosis) of the tissues in that area.