Blood Clots

Also called: Hypercoagulability

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Summary

Normally, if you get hurt, your body forms a blood clot to stop the bleeding. After the bleeding stops and healing takes place, your body usually breaks down and removes the clot. But some people get too many clots or their blood clots abnormally. Many conditions can cause the blood to clot too much or prevent blood clots from dissolving properly.

Risk factors for excessive blood clotting include

Certain genetic disorders
Atherosclerosis
Diabetes
Atrial fibrillation
Overweight, obesity, and metabolic syndrome
Some medicines
Smoking
Staying in one position for a long time, such as being in the hospital or taking a long car or plane ride
Cancer and cancer treatments

Blood clots can form in, or travel to, the blood vessels in the brain, heart, kidneys, lungs, and limbs. A clot in the veins deep in the limbs is called deep vein thrombosis (DVT). DVT usually affects the deep veins of the legs. If a blood clot in a deep vein breaks off and travels through the bloodstream to the lungs and blocks blood flow, it is called a pulmonary embolism. Other complications of blood clots include stroke, heart attack, kidney problems, kidney failure, and pregnancy-related problems. Treatments for blood clots include blood thinners and other medicines.

Start Here

Blood Clots (American Society of Hematology)
Blood Clots (Mayo Foundation for Medical Education and Research)
Blood Clots (Radiological Society of North America) Also in Spanish
How Blood Clots (Merck & Co., Inc.) Also in Spanish

Diagnosis and Tests

Antithrombin Test (American Association for Clinical Chemistry)
Coagulation Factor Tests (National Library of Medicine) Also in Spanish
D-dimer Test (American Association for Clinical Chemistry)
Factor V Leiden Mutation and PT 20210 Mutation Test (American Association for Clinical Chemistry)
Fibrinogen Test (American Association for Clinical Chemistry)
MPV Blood Test (National Library of Medicine) Also in Spanish
Partial Thromboplastin Time (PTT, aPTT) (American Association for Clinical Chemistry)
PT and INR Test (American Association for Clinical Chemistry)
Thrombin Time (American Association for Clinical Chemistry)

Treatments and Therapies

Blood Thinners: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
Catheter-Directed Thrombolysis (Radiological Society of North America) Also in Spanish

Related Issues

Blood Clots and Travel: What You Need to Know (Centers for Disease Control and Prevention) Also in Spanish
Blood Thinners: Can I Still Get Blood Clots? (Mayo Foundation for Medical Education and Research) Also in Spanish
Important Information to Know When You Are Taking: Warfarin (Coumadin) and Vitamin K (National Institutes of Health, Clinical Center) - PDF Also in Spanish
Understand Your Risk for Excessive Blood Clotting (American Heart Association)

Specifics

Antiphospholipid Syndrome (National Institute of Neurological Disorders and Stroke)
Cerebral and Sinus Vein Thrombosis (American Heart Association)
Factor V Leiden (Mayo Foundation for Medical Education and Research) Also in Spanish
Hypercoagulation (American Academy of Family Physicians) Also in Spanish
Thrombophilia and Hypercoagulability (American Heart Association)
Thrombophlebitis (Mayo Foundation for Medical Education and Research)
Thrombotic Thrombocytopenic Purpura (National Heart, Lung, and Blood Institute)
What Is Antiphospholipid Antibody Syndrome? (National Heart, Lung, and Blood Institute)
What Is Disseminated Intravascular Coagulation? (National Heart, Lung, and Blood Institute)

Genetics

Genetics Home Reference: antiphospholipid syndrome (National Library of Medicine)
Genetics Home Reference: clopidogrel resistance (National Library of Medicine)
Genetics Home Reference: factor V Leiden thrombophilia (National Library of Medicine)
Genetics Home Reference: hereditary antithrombin deficiency (National Library of Medicine)
Genetics Home Reference: protein C deficiency (National Library of Medicine)
Genetics Home Reference: protein S deficiency (National Library of Medicine)
Genetics Home Reference: prothrombin thrombophilia (National Library of Medicine)
Genetics Home Reference: von Willebrand disease (National Library of Medicine)
Genetics Home Reference: warfarin resistance (National Library of Medicine)
Learning about Antiphospholipid Syndrome (APS) (National Human Genome Research Institute)
Learning about Factor V Leiden Thrombophilia (National Human Genome Research Institute)

Videos and Tutorials

Blood clotting (Medical Encyclopedia) Also in Spanish

Clinical Trials

ClinicalTrials.gov: Thrombosis (National Institutes of Health)
ClinicalTrials.gov: Venous Thrombosis (National Institutes of Health)

Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)

Find an Expert

Centers for Disease Control and Prevention Also in Spanish
Find a Hematologist (American Society of Hematology)
National Heart, Lung, and Blood Institute

Children

Blood (For Parents) (Nemours Foundation) Also in Spanish

Women

Postpartum Blood Clots (Merck & Co., Inc.) Also in Spanish

Patient Handouts

Arterial embolism (Medical Encyclopedia) Also in Spanish
Blood clots (Medical Encyclopedia) Also in Spanish
D-dimer test (Medical Encyclopedia) Also in Spanish
Prothrombin time (PT) (Medical Encyclopedia) Also in Spanish
Superficial thrombophlebitis (Medical Encyclopedia) Also in Spanish
Thrombophlebitis (Medical Encyclopedia) Also in Spanish