Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets (thrombocytes) and fibrin to form a blood clot to prevent blood loss. Even when a blood vessel is not injured, blood clots may form in the body under certain conditions. A clot, or a piece of the clot, that breaks free and begins to travel around the body is known as an embolus.
Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathing in, and coughing up blood. Symptoms of a blood clot in the leg may also be present, such as a red, warm, swollen, and painful leg. Signs of a PE include low blood oxygen levels, rapid breathing, rapid heart rate, and sometimes a mild fever. Severe cases can lead to passing out, abnormally low blood pressure, and sudden death.
Venous thrombosis is thrombosis in a vein, caused by a thrombus. The most common form of venous thrombosis is a deep vein thrombosis (DVT), when a blood clot forms in the deep veins of the leg. If the thrombus breaks off and flows towards the lungs, it can become a pulmonary embolism (PE), a blood clot in the lungs. This combination is called venous thromboembolism. Various other forms of venous thrombosis also exist; some of these can also lead to pulmonary embolism.
Factor V Leiden is a variant of human factor V, which causes an increase in blood clotting (hypercoagulability). Due to this mutation, protein C, an anticoagulant protein which normally inhibits the pro-clotting activity of factor V, is not able to bind normally to factor V, leading to a hypercoagulable state, i.e., an increased tendency for the patient to form abnormal and potentially harmful blood clots. Factor V Leiden is the most common hereditary hypercoagulability disorder amongst ethnic Europeans. It is named after the Dutch city Leiden, where it was first identified in 1994 by Prof R. Bertina under the direction of Prof P. Reitsma. Despite the increased risk of VTE, people with one copy of this gene have not been found to have shorter lives than the general population.
Deep vein thrombosis (DVT) is the formation of a blood clot in a deep vein, most commonly in the legs or pelvis. Symptoms can include pain, swelling, redness, and enlarged veins in the affected area, but some DVTs have no symptoms. The most common life-threatening concern with DVT is the potential for a clot to detach from the veins (embolize), travel through the right side of the heart, and become stuck in arteries that supply blood to the lungs. This is called pulmonary embolism (PE). Both DVT and PE are considered as part of the same overall disease process, which is called venous thromboembolism (VTE). VTE can occur as DVT only, as PE with DVT, or PE without DVT. The most frequent long-term complication is post-thrombotic syndrome, which can cause pain, swelling, a sensation of heaviness, itching, and in severe cases, ulcers. Also, recurrent VTE occurs in about 30% of those in the ten years following an initial VTE.
D-dimer is a fibrin degradation product, a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. It is so named because it contains two D fragments of the fibrin protein joined by a cross-link.
Paget–Schroetter disease, is a form of upper extremity deep vein thrombosis (DVT), a medical condition in which blood clots form in the deep veins of the arms. These DVTs typically occur in the axillary and/or subclavian veins.
Post-thrombotic syndrome (PTS), also called postphlebitic syndrome and venous stress disorder is a medical condition that may occur as a long-term complication of deep vein thrombosis (DVT).
CT pulmonary angiogram (CTPA) is a medical diagnostic test that employs computed tomography (CT) angiography to obtain an image of the pulmonary arteries. Its main use is to diagnose pulmonary embolism (PE). It is a preferred choice of imaging in the diagnosis of PE due to its minimally invasive nature for the patient, whose only requirement for the scan is an intravenous line.
Superficial thrombophlebitis is a thrombosis and inflammation of superficial veins which presents as a painful induration with erythema, often in a linear or branching configuration forming cords.
Intermittent pneumatic compression is a therapeutic technique used in medical devices that include an air pump and inflatable auxiliary sleeves, gloves or boots in a system designed to improve venous circulation in the limbs of patients who suffer edema or the risk of deep vein thrombosis (DVT) or pulmonary embolism (PE).
Bancroft's sign, also known as Moses' sign, is a clinical sign found in patients with deep vein thrombosis of the lower leg involving the posterior tibial veins. The sign is positive if pain is elicited when the calf muscle is compressed forwards against the tibia, but not when the calf muscle is compressed from side to side. Like other clinical signs for deep vein thrombosis, such as Homans sign and Lowenberg's sign, this sign is neither sensitive nor specific for the presence of thrombosis.
Lowenberg's sign is a clinical sign found in patients with deep vein thrombosis of the lower leg. The sign is positive when pain is elicited rapidly when a blood pressure cuff is placed around the calf and inflated to 80mmHg. Like other signs of deep vein thrombosis, such as Homans sign and Bancroft's sign, this sign is neither sensitive nor specific for the presence of thrombosis.
Blood clots are a relatively common occurrence in the general population and are seen in approximately 1-2% of the population by age 60. Typically blood clots develop in the deep veins of the lower extremities, deep vein thrombosis (DVT) or as a blood clot in the lung, pulmonary embolism (PE). A very small number of people who develop blood clots have a more serious and often life-threatening condition, known as Thrombotic Storm (TS). TS is characterized by the development of more than one blood clot in a short period of time. These clots often occur in multiple and sometimes unusual locations in the body and are often difficult to treat. TS may be associated with an existing condition or situation that predisposes a person to blood clots such as injury, infection, or pregnancy. In many cases a risk assessment will identify interventions that will prevent the formation of blood clots.
Apixaban, sold under the brand name Eliquis among others, is an anticoagulant medication used to treat and prevent blood clots and to prevent stroke in people with nonvalvular atrial fibrillation. Specifically it is used to prevent blood clots following hip or knee replacement and in those with a history of prior clots. It is used as an alternative to warfarin and does not require monitoring by blood tests. It is taken by mouth.
Peabody's sign is a clinical sign which may be found in patients with deep vein thrombosis (DVT). The sign is positive when calf muscle spasm occurs on raising the affected leg with the foot extended. The sign is neither sensitive nor specific for the presence of DVT.
Superficial vein thrombosis (SVT) is a type blood clot in a vein, which forms in a superficial vein near the surface of the body. Usually there is thrombophlebitis, which is an inflammatory reaction around a thrombosed vein, presenting as a painful induration with redness. SVT itself has limited significance when compared to a deep vein thrombosis (DVT), which occurs deeper in the body at the deep venous system level. However, SVT can lead to serious complications, and is therefore no longer regarded as a benign condition. If the blood clot is too near the saphenofemoral junction there is a higher risk of pulmonary embolism, a potentially life-threatening complication.
Thrombosis prevention or thromboprophylaxis is medical treatment to prevent the development of thrombosis in those considered at risk for developing thrombosis. Some people are at a higher risk for the formation of blood clots than others. Prevention measures or interventions are usually begun after surgery as people are at higher risk due to immobility.
Ultrasonography in suspected deep vein thrombosis focuses primarily on the femoral vein and the popliteal vein, because thrombi in these veins are associated with the greatest risk of harmful pulmonary embolism.
Henri Bounameaux is a known clinical faculty and Professor of Medicine (hon), specialized in internal and vascular medicine (angiology), and general medicine.
