A blood clot is a gel-like mass formed by platelets and fibrin in the blood. The body forms blood clots to stop bleeding caused by a cut or injury by repairing damage to a blood vessel (either an artery or vein). Blood clots are healthy and lifesaving when they stop bleeding.

When blood clots form inappropriately inside an artery or vein, they may cause significant problems because blood flow past the clot is decreased. This may cause a heart attack, stroke, or other serious medical problems.

There are a variety of risk factors and illnesses that can lead to blood clot formation. These include:

  • Heart conditions, including atrial fibrillation, a heart rhythm disturbance
  • Pregnancy
  • Prolonged immobility
  • Smoking
  • Certain medications, including birth control pills
  • Surgery, especially orthopedic procedures when casts or splints are placed and the patient is immobile
  • Inherited blood clotting disorders

Symptoms of blood clots depend on their location in the body. Some blood clots produce no symptoms until they rupture or become dislodged and travel through the circulatory system to other sites.

  • Blood clots in the legs, called deep vein thrombosis (DVT), cause pain, redness, and swelling.
  • An arterial blood clot in the leg cause are painful and cause the leg to feel cool and appear pale.
  • Blood clots in the lung, called pulmonary emboli, cause chest pain, shortness of breath, and rapid pulse and breathing.
  • A blood clot in an artery of the brain, more popularly known as a stroke, cause loss of speech, vision, and weakness on one side of the body.
  • A blood clot in an artery of the heart (coronary artery), more popularly known as a heart attack, cause chest pain, shortness of breath, nausea, indigestion, and sweating.
  • A blood clot in an artery that supplies the intestines, called mesenteric ischemia, cause abdominal pain, nausea, and blood in stool.


The diagnosis of a blood clot is suggested by the patient’s medical history and physical examination and is often confirmed with an imaging test, such as a CT or MRI scan. Depending upon the location of the blood clot and its cause, treatment may require surgery, anti-coagulation medications, or a combination of the two.



The treatment of blood clots often involves interfering with the normal clotting mechanism of the body. Different medications may be used to block specific factors in the clotting process. Medications are chosen based on the disease or illness being treated and other underlying medical issues that are present in the individual patient. Some medications prevent additional or future blood clots while others can help dissolve existing blood clots.

Aspirin is commonly used to decrease platelet function in the treatment of heart attack and stroke.

Other anti-platelet drugs include:

  • Clopidogrel (Plavix)
  • Prasugrel (Effient)
  • Ticagrelor (Brillanta)
  • Ticlopidine (Ticlid)  
  • Dipyridamole (Aggrenox)

Warfarin (Coumadin) acts as a blood thinner by blocking certain clotting factors dependent on vitamin K. Because every patient is unique when it comes to the dosing requirements for warfarin (coumadin), repeat blood tests are routinely done to make certain that the blood is anti-coagulated to the appropriate level. There are numerous drug interactions with this medication that can cause the blood to become “too thin” such as some antibiotics. Warfarin (Coumadin) dosing always needs to be monitored by a healthcare professional, and a patient should never alter the dose of this medication without consulting with their healthcare professional.

Factor Xa Inhibitor medications have been approved for the treatment of certain types of atrial fibrillation, deep venous thrombosis and pulmonary embolism. They begin working almost immediately and do not need blood tests to monitor their activity. Medications in this class of anticoagulants include:

  • Apixaban (Eliquis)
  • Rivaroxaban (Xarelto)
  • Edoxaban (Savaysa)

Dabigatran (Pradaxa) also is an alternative anticoagulation medication that is a direct thrombin inhibitor. As opposed to warfarin, which can have its anticoagulation activity reversed, at present there is no reversal agent available for Factor Xa and thrombin inhibitor medications. These medications also may be used to help prevent blood clots in the leg after hip and knee replacement surgery.

Heparin works by inactivating thrombin and clotting factor X. It is an injectable medication available for use intravenously or as a low molecular weight medication called enoxaparin (Lovenox) or fondaparinux (Arixtra), which can be injected subcutaneously (under the skin). Heparin is often used routinely as part of the heart attack treatment protocol. Because of its rapid onset of action it is often the first medication started once a blood clot is diagnosed in the hospital.

Tissue Plasminogen Activator (TPA or TNK) may be used to dissolve blood clots that are life-threatening and are most often used for clots that occlude arteries in situations such as stroke or heart attack; there are occasional instances in which the drug is used for major vein obstruction. The medication can be injected into an intravenous line that has been started in a vein of the arm, or it may be dripped directly into the clot. This requires specialized critical care technology and physician skill to thread a catheter to the site of blockage to deliver the clot-busting medication. Decisions regarding the use of this drug are individualized for the specific patient and situation.

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