Blood Clot Formation  

Doctors call a blood clot is a "thrombus." The plural is "thrombi." A thrombus can also form if a vein or artery becomes obstructed and slows down the efficient flow of blood. When blood stagnates in this way, it can cause localized pain. But there can also be serious - even life-threatening - consequences.

Medical professionals classify several kinds of blood clots.

Venous thrombus  

This type of clot happens in a vein. If you are immobilized due to an accident or injury, your muscles doesn't move as much. Since you aren't using your muscles, the normal contraction process, which helps keep blood flowing, is limited. Circulation slows down and blood starts to stagnate in certain areas around your body. If this interruption of blood flow continues for a long enough period of time, blood clots, or thrombi, begin to form. When this happens, blood flow becomes even more restricted, which contributes not only to pain, but also to additional clot formation.

Certain circumstances often lead to the formation of a thrombus.

• When a serious illness or surgery requires hospitalization or extended bedrest.
• When one of your limbs is immobilized or put in a cast.
• When you're traveling and you have to sit in one place for a long time. Thrombi can form in a relatively short period of time, like an intercontinental airplane flight or even a extended driving trip.
• When you're pregnant, because the fetus may block blood flow in certain veins as he or she grows.

Certain people are born with a genetic predisposition to blood clot formation. Their blood tends to clot more quickly than other individuals.

One of the most serious dangers related to blood clot formation is a condition known as DVT, or deep vein thrombosis. DVT occurs when a blood clot forms in a vein, then is pushed by normal blood circulation back to the heart. From there, the clot is pumped to the lungs where it can lodge in a blood vessel, blocking the supply of blood and oxygen. This is a medical emergency that requires urgent attention because it is potentially fatal.

Another potentially fatal condition called atrial fibrillation is possible. This is caused by small thrombi that originate in the walls of the heart. These thrombi get into in the circulatory system and block the flow of blood. Tissues in the area die because they can't get the oxyhen and nutrients they need.

Arterial fibrillation happens most often near the brain (triggering a stroke) or in the intestines (causing a condition called mesenteric ischemia).

Arterial thrombus

There's another type of blood clot formation that occurs in the arteries. These clots are called "arterial thrombi." They are different from venous thrombi because they form gradually in arteries that have become obstructed by fatty plaque that grows on artery walls. Arteries that have degraded in this way are the root cause of heart disease, heart attacks and strokes.

Sometimes, an arterial thrombus forms because an artery ruptures.

The typical causes of arterial thrombi include high blood pressure (hypertension), high cholesterol, diabetes, and smoking.

The best way to prevent blood clot formation is to keep your cholesterol levels normal, lower your blood pressure if it is high, and avoid diabetes by eating healthy foods and getting regular exercise. 

Also see blood clot pain, blood clot diagnosis, blood clot treatment and blood clot prevention.