During hemostasis, the normal stagnation of bleeding, a blood clot forms through the process of coagulation, but sometimes a clot forms inside a deep vein. Known as deep vein thrombosis (DVT), this kind of blood clot poses serious health threats.

According to the American Thrombosis Association, approximately 2 million people are affected by DVT each year and around 74 percent of Americans are unaware of the disease.

Types
Relatively harmless clots known as superficial phlebitis can form near the surface of the skin in small veins.

On the other hand, DVT, which typically afflicts a leg, can break loose and travel through the blood steam to the lungs, resulting in a fatal pulmonary embolism (PE).

If a clot travels to the heart it will cause a heart attack; if it's to the brain, it will cause a stroke.

Causes
A blood clot can occur in many places throughout the body. Most form when something prevents blood from circulating normally.

Dana S Simpler, an internist in Baltimore, explained that DTV "commonly forms after prolonged bed rest or travel where the calves have been still and the blood can pool and clot in the veins." Hereditary factors, birth control pills and hormone therapy increase the risk of occurrence.

Symptoms
The National Blood Clot Alliance warns that swelling, pain, tenderness, reddish or bluish skin discoloration and unusual warmness are common symptoms of DVT, typically in the legs. These indicators are similar to those of a Charlie horse or a pulled muscle.

Signs of PT include breathlessness, stabbing chest pain, increased heart rate and unusual coughing.

Diagnosis
There are a few methods for determining whether someone has DVT. Blood tests can see if a patient has a heightened level of D dimer, a clot-dissolving substance that increases when one has DVT.

CT and MRI scans can generate images of the clot for inspection. Ultrasounds can create a moving image of the suspected clot on a video screen with a transducer.

If the previous methods cannot successfully diagnose DVT, doctors might use the more invasive approach of venography, in which a doctor injects dye into the vein and produces an X-ray. The dye helps make the contrast between blood and the rest of the leg more apparent, helping in diagnosis, according to the Mayo Clinic.

Treatment
Anticoagulants, or blood thinners, are central to blood clot treatment. They prevent the growth of the clot. Bleeding is a common side effect.

The Agency for Healthcare Research and Quality reports that the doctor usually performs heparin injections for the first week of treatment. Heparin starts anti-coagulating blood within minutes. This process requires monitoring.

According to Simpler, just a few years ago, the injectable medicine lovenox (brand name: Enoxaparin) enabled people to go home immediately after diagnosis. Both heparin and lovenox should be followed with an oral medication.

Then, the patient begins taking warfarin pills (brand name: Coumadin), for long-term anticoagulation.