DVT, Blood Clots, and Thrombophlebitis

In medicine, deep vein thrombosis (also known as deep venous thrombosis and usually abbreviated as DVT) is the formation of a blood clot ("thrombus") in a deep vein. Deep vein thrombosis commonly affects the leg veins (such as the femoral vein or the popliteal vein) or the deep veins of the pelvis. Occasionally the veins of the arm are affected. A DVT can occur without symptoms, but in many cases the affected extremity will be painful, swollen, red, warm and the superficial veins may be engorged. The most serious complication of a DVT is that the clot could dislodge and travel to the lungs, which is called a pulmonary embolism (PE). DVT is a medical emergency. Limb swellings however trivial, should be evaluated for DVT.



DVT of the lower extremities can be diagnosed by ultrasound. Untreated lower extremity DVT has a 3% PE-related mortality rate. Deaths associated with upper extremity DVT are extremely rare. A late complication of DVT is the post-thrombotic syndrome, which can manifest itself as edema, pain or discomfort, skin problems, and ulcers of the skin of the leg below the knee.   According to Virchow's triad, venous thrombosis occurs via three mechanisms: decreased flow rate of the blood, damage to the blood vessel wall and an increased tendency of the blood to clot (hypercoagulability). Several medical conditions can lead to DVT, such as compression of the veins, physical trauma, cancer, infections, certain inflammatory diseases and specific conditions such as stroke, heart failure or nephrotic syndrome. There are several factors which can increase a person's risk for DVT, including major surgery, prolonged hospitalization, prolonged immobilization (such as when orthopedic casts are used), smoking, obesity, age, certain drugs (such as estrogen or erythropoietin) and inborn tendencies to form clots known as thrombophilia (for example, in carriers of factor V Leiden deficiency). Women have an increased risk during pregnancy and in the postnatal period. Women who use oral contraceptives absolutely should not smoke.  The most commonly used tests for the diagnosis of DVT is ultrasound. There are also blood tests called D-dimers. Sometimes, further testing is required to find the cause of the DVT. In specific cases, an attempt can be made to break down the clot (using thrombolytic agents given intravenously) or using catheter based therapy to mechanically break up the clot. To prevent further accrual and formation of new clots with a risk of pulmonary embolism, anticoagulation (blood thinners) is advised (if not possible, an inferior vena cava filter may be used). Prevention of DVT is advised in many medical and surgical inpatients using anticoagulants, graduated compression stockings (also known as thromboembolic deterrent stockings) or intermittent pneumatic compression (IPC) devices.