Hypercoagulable states are conditions that may lead to the abnormal development of blood clots. Blood clots can develop in either arteries or veins.

See also:

• Blood clots in the legs
• Deep venous thrombosis (DVT)
• Hepatic vein obstruction (Budd-Chiari syndrome)
• Mesenteric vein thrombosis
• Pulmonary embolus
• Stroke
• Stroke secondary to cardiogenic embolism

Conditions that can lead to the formation of blood clots include prolonged bedrest, dehydration, poor positioning (such as crossing the legs), sitting for long periods (such as in a plane or car), and prolonged use of an intravenous catheter.

Some medical situations can lead to the formation of abnormal blood clots. These include cancer, recent surgery or trauma, obesity, liver or kidney disease, and some medications.

In women, birth control pills or hormone replacement therapy increase the risk of blood clots, and the risk is greatly increased in those who also smoke. The periods before, during, and after pregnancy also increase the risk of clots.

A tendency to form abnormal blood clots also can be related to genetic problems. For example, two relatively common inherited conditions that affect clotting are Factor V Leiden and the Prothrombin mutation 20210A. Rare inherited conditions include Protein C, Protein S, and Anti-thrombin III deficiencies.