Description

• Development of blood clot within the deep veins, usually accompanied by inflammation of the vessel wall
• Major clinical consequences are embolization (usually to the lung), recurrent thrombosis, and postphlebitic syndrome.

Epidemiology

• Age- and gender-adjusted incidence of venous thromboembolism (VTE) is 100 times higher in the hospital than in the community. Almost half of all VTEs occur either during or soon after discharge from a hospital stay or surgery.
• 10–30% of patients diagnosed with DVT and/or pulmonary embolism (PE) will die within 1 month of diagnosis
• Of patients with VTE, 20% complicated with PE. The 28-day deep venous thrombosis (DVT) fatality rate is 5.4%; at 1 year, 20%; at 3 years, 29%.

• In the United States, VTE incidence is 50.4/100,000 person per year.
• Increased incidence in Caucasian and African American populations and with aging
• Most common site: lower extremity DVT
• Incidence in pregnancy: ~0.5 to 3/1,000 (1)
• 1–5% of central venous catheters are complicated by thrombosis (2).

• Variable; depends on medical condition or procedure
• At time of DVT diagnosis, as many as 40% of patients also have asymptomatic PE; conversely, 30% of patients diagnosed with PE do not a have demonstrable source.
• Present in 11% of patients with acquired brain injury entering neurorehabilitation

Etiology and Pathophysiology

Factors involved may include venous stasis, endothelial injury, and hypercoagulability (Virchow triad).

• Factor V Leiden, the most common thrombophilia, is found in 5% of the population and in 10–65% of all VTE events and increases VTE risk 3- to 6-fold.
• Prothrombin G20210A is found in 3% of Caucasians; increases the risk of thrombosis ~3-fold

Risk Factors

• Acquired: previous DVT, cancer, immobilization, trauma, traumatic brain injury, obesity, recent major surgery, medications (oral contraceptives, estrogens, tamoxifen), obesity, smoking, antiphospholipid syndrome, acute infectious process, thrombocytosis, pregnancy/puerperium, central venous catheters
• Hereditary: deficiencies of protein C, protein S, or antithrombin III; factor V Leiden R506Q, prothrombin G20210A mutation, dysfibrinogenemia, elevated factor VIII activity, hyperhomocysteinemia

General Prevention

• Mechanical thromboprophylaxis is recommended in patients with high bleeding risk and as adjunct to pharmacologic thromboprophylaxis.
• For acutely ill and for critically ill hospitalized patients at increased risk of thrombosis, low-molecular-weight heparin (LMWH), low-dose unfractionated heparin, or fondaparinux are recommended (3)[C].
• For most patients, prolonged secondary prophylaxis is not recommended.
• In patients undergoing major abdominal surgery for malignancy, LMWH for up to 4 weeks after surgery has been shown to decrease the incidence of VTE without increased bleeding.