Blood clots

Alternative Names: Clot; Emboli; Thrombi

Blood clots are clumps that occur when blood hardens from a liquid to a solid.

A blood clot that forms inside a blood vessel or within the heart and stays there is called a thrombus. A thrombus that breaks loose and travels from one location in the body to another is called an embolus. The related medical disorder is called an embolism. For example, an embolus that gets stuck in the lungs is called a pulmonary embolism.

Sometimes other materials can act like an embolus and block blood flow, including:

• Air
• Amniotic fluid
• A piece of atherosclerotic plaque
• Fat clumps
• Small pieces of tumor

See also:

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

Potential Complications

Thrombi and emboli can firmly attach to a blood vessel. They can partially or completely block the flow of blood in that vessel.

A blockage in the blood vessel prevents normal blood flow and oxygen from reaching the tissues in that location. This is called ischemia. If ischemia is not treated promptly, it can result in tissue damage, or death of the tissues in that area.

Lim W, Crowther MA, Ginsberg JS. Venous thromboembolism. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 135.

Krakow EF, Ginsberg JS, Crowther MA. Arterial thromboembolism. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 136.

Thrombus	Janeway lesion on the finger	Deep venous thrombosis, ileofemoral

Review Date: 6/2/2010
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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