Dr

When you get a cut, your body stops the bleeding by forming a blood clot (a thickened mass). Substances in your blood (called proteins) work with tiny particles (called platelets) to form the clot. Forming a clot is called "coagulation." Coagulation helps when you are injured because it slows blood loss. However, your blood shouldn't clot when it's moving through your body. If blood clots inside your blood vessels, it's called "thrombosis" or "phlebitis." The tendency to clot too much is called "hypercoagulation." It can be very dangerous.

When abnormal clots occur, they usually form inside veins (the vessels that carry blood to the heart). A clot inside a blood vessel is called a "thrombus." Sometimes the thrombus can travel in the bloodstream and get stuck in your lungs. This kind of clot, called a "pulmonary embolus," keeps blood from getting to your lungs. A pulmonary embolus can be life-threatening.

A clot that blocks a blood vessel in the brain can cause a stroke. A clot in a blood vessel in the heart can cause a heart attack. Blood clots can cause some women to have miscarriages.

Certain situations or risk factors can make it easier for your blood to clot too much. These situations include the following:

Some people are born with a tendency to develop clots. This tendency is inherited (it comes from your parents). Most of the time, increased clotting happens because the anti-clotting protein C in the blood isn't doing its job properly.

In some people, the blood clots too much because their body doesn't make enough anti-clotting protein C or protein S, or they have antithrombin III (another type of protein) that doesn't work. Some people have an extra protein in their blood that causes too much clotting. Hypercoagulation has a few other causes, but those causes are rare.

If your doctor suspects you have hypercoagulation, tests can check the proteins in your blood. The tests will also show if your proteins are working the right way.

Yes. Several medicines can thin your blood and make it less likely to clot. Some people with hypercoagulation only need to take blood thinners when they're in a situation that makes them more likely to form clots--like when they're in the hospital recovering from surgery, when they're in a car or airplane for a long time and when they're pregnant. Other people need to take medicine for the rest of their lives. Your doctor will decide which group you're in.

The two most common blood thinners are called heparin and warfarin (brand name: Coumadin). Your doctor will probably give you heparin first, because heparin works right away. Heparin must be injected with a small needle under the skin. Once the heparin starts working, your doctor will probably have you start taking oral warfarin. Warfarin takes longer to begin working.

Both medicines can cause you to bleed more easily. You might notice that if you cut yourself, the blood takes longer to clot. You might bruise more easily. If you have any unusual or heavy bleeding, call your doctor.

Warfarin has a stronger effect on some people than on others. If you take warfarin, your doctor will want to check you often with a blood test called the PT-INR. This test will tell your doctor how well the warfarin is working. Some other medicines can make warfarin more or less strong. Ask your doctor before you take a new medicine, even nonprescription medicines and vitamins.

If you're pregnant, you shouldn't take warfarin. Warfarin can cause birth defects. Instead, you must use heparin until you have your baby. If you want to get pregnant and you're already taking warfarin, talk with your doctor about changing to heparin. Sexually active women who take warfarin should use birth control.